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The biggest mass extinction and Pangea integration

Relationships between geosphere disturbances and mass extinction during the Late Permian and Early Triassic are shown. Credit: Science China Press

Relationships between geosphere disturbances and mass extinction during the Late Permian and Early Triassic are shown. Credit: Science China PressThe mysterious relationship between Pangea integration and the biggest mass extinction happened 250 million years ago was tackled by Professor YIN Hongfu and Dr. SONG Haijun from State Key Laboratory of Geobiology and Environmental Geology, China University of Geosciences (Wuhan). Their study shows that Pangea integration resulted in environmental deterioration which further caused that extinction. Their work, entitled “Mass extinction and Pangea integration during the Paleozoic-Mesozoic transition”, was published in Science Сhina Earth Sciences.2013, Vol 56(7).

The Pangea was integrated at about the beginning of Permian, and reached its acme during Late Permian to Early Triassic. Formation of the Pangea means that the scattered continents of the world gathered into one integrated continent with an area of nearly 200 million km2. Average thickness of such a giant continental lithosphere should be remarkably greater than that of each scattered continent. Equilibrium principle implies that the thicker the lithosphere, the higher its portion over the equilibrium level, hence the average altitude of the Pangea should be much higher than the separated modern continents. Correspondingly, all oceans gathered to form the Panthalassa, which should be much deeper than modern oceans. The acme of Pangea and Panthalassa was thus a period of high continent and deep ocean, which should inevitably induce great regression and influence the earth’s surface system, especially climate.

The Tunguss Trap of Siberia, the Emeishan Basalt erupted during the Pangea integration. Such global-scale volcanism should be evoked by mantle plume and related with integration of the Pangea. Volcanic activities would result in a series of extinction effects, including emission of large volume of CO2, CH4, NO2 and cyanides which would have caused green house effects, pollution by poisonous gases, damage of the ozone layer in the stratosphere, and enhancement the ultra-violet radiation.

Increase of CO2 concentration and other green house gases would have led to global warming, oxygen depletion and carbon cycle anomaly; physical and chemical anomalies in ocean (acidification, euxinia, low sulfate concentration, isotopic anomaly of organic nitrogen) and great regression would have caused marine extinction due to unadaptable environments, selective death and hypercapnia; continental aridity, disappearance of monsoon system and wild fire would have devastated the land vegetation, esp. the tropical rain forest.

The great global changes and mass extinction were the results of interaction among earth’s spheres. Deteriorated relations among lithosphere, atmosphere, hydrosphere, and biosphere (including internal factors of organism evolution itself) accumulated until they exceeded the threshold, and exploded at the Permian-Triassic transition time. Interaction among bio- and geospheres is an important theme. However, the processes from inner geospheres to earth’s surface system and further to organism evolution necessitate retardation in time and yields many uncertainties in causation. Most of the processes are now at a hypothetic stage and need more scientific examinations.

More information: Yin H F, Song H J. Mass extinction and Pangea integration during the Paleozoic-Mesozoic transition. Science China: Earth Sciences, 2013, 56: 1791-1803. http://earth.scichina.com:8080/sciDe/EN/10.1007/s11430-013-4624-3

Note : The above story is based on materials provided by Science China Press

Geoscientists building whole-Earth model for long-term climate clues

A Rice University-based team of geoscientists is going to great lengths — from Earth’s core to its atmosphere — to investigate the role that deep-Earth processes play in climate evolution over million-year timescales. Credit: Rice University

A Rice University-based team of geoscientists is going to great lengths—from Earth’s core to its atmosphere—to get to the bottom of a long-standing mystery about the planet’s climate.

 

“We want to know what controls long-term climate change on Earth, the oscillations between greenhouse and icehouse cycles that can last as long as tens of million years,” said Cin-Ty Lee, professor of Earth science at Rice and the principal investigator (PI) on a new $4.3 million, five-year federal grant from the National Science Foundation’s Frontiers in Earth-System Dynamics (FESD) Program.

“There are long periods where Earth is relatively cool, like today, where you have ice caps on the North and South poles, and there are also long periods where there are no ice caps,” Lee said. “Earth’s climate has oscillated between these two patterns for at least half a billion years. We want to understand what controls these oscillations, and we have people at universities across the country who are going to attack this problem from many angles.”

For starters, Lee distinguished between the type of climate change that he and his co-investigators are studying and the anthropogenic climate change that often makes headlines.

“We’re working on much longer timescales than what’s involved in anthropogenic climate change,” Lee said. “We’re interested in explaining processes that cycle over tens of millions of years.”

Lee described the research team as “a patchwork of free spirits” that includes bikers, birdwatchers and skateboarders who are drawn together by a common interest in studying the whole Earth dynamics of carbon exchange. The group has specialists in oceanography, petrology, geodynamics, biogeochemistry and other fields, and it includes more than a dozen faculty and students from the U.S., Europe and Asia. Rice co-PIs include Rajdeep Dasgupta, Gerald Dickens and Adrian Lenardic.

The team will focus on how carbon moves between Earth’s external and internal systems. On the external side, carbon is known to cycle between oceans, atmosphere, biosphere and soils on timescales ranging from a few days to a few hundred thousand years. On million-year to billion-year timescales, carbon in these external reservoirs interacts with reservoirs inside Earth, ranging from crustal carbon stored in ancient sediments preserved on the continents to carbon deep in Earth’s mantle.

“Because of these differences in timescales, carbon cycling at Earth’s surface is typically modeled independently from deep-Earth cycling,” Lee said. “We need to bring the two together if we are to understand long-term greenhouse-icehouse cycling.”

From the fossil record, scientists know that atmospheric carbon dioxide plays a vital role in determining Earth’s surface temperatures. Many studies have focused on how carbon moves between the atmosphere, oceans and biosphere. Lee said the FESD team will examine how carbon is removed from the surface and cycled back into the deep Earth, and it will also examine how volcanic eruptions bring carbon from the deep Earth to the surface. In addition, the team will examine the role that volcanic activity and plate tectonics may play in periodically releasing enormous volumes of carbon dioxide into the atmosphere.

One of several hypotheses that will be tested is whether Earth’s subduction zones may at times be dominated by continental arcs, and if so, whether the passage of magmas through ancient carbonates stored in the continental upper plate can amplify the volcanic flux of carbon.

“Long-term climate variability is intimately linked to whole-Earth carbon cycling,” Lee said. “Our task is to build up a clearer picture of how the inputs and outputs change through time.”

In addition to the Rice team, the project’s primary investigators include Jaime Barnes of the University of Texas at Austin, Jade Star Lackey of Pomona College, Michael Tice of Texas A&M University and Richard Zeebe of the University of Hawaii. Research affiliates include Steve Bergman of Shell, Mark Jellinek of the University of British Columbia, Tapio Schneider of the Swiss Federal Institute of Technology and Yusuke Yokoyama of the University of Tokyo.

Note : The above story is based on materials provided by Rice University

Scientists Digitally Reconstruct Giant Steps Taken by Dinosaurs for the First Time

This is the 40-meter original skeleton, Argentinosaurus huinculensis reconstruction at Museo Municipal Carmen Funes, Plaza Huincul, Neuquén, Argentina. (Credit: Dr. Bill Sellers, The University of Manchester)

The Manchester team, working with scientists in Argentina, were able to laser scan a 40 metre-long skeleton of the vast Cretaceous Argentinosaurus dinosaur. Then using an advanced computer modeling technique involving the equivalent of 30,000 desktop computers they recreated its walking and running movements and tested its locomotion ability tested for the very first time.

The study, published in PLOS ONE, provides the first ever ‘virtual’ trackway of the dinosaur and disproves previous suggestions that the animal was inflated in size and could not have walked.

Dr Bill Sellers, lead researcher on the project from the University’s Faculty of Life Sciences, said: “If you want to work out how dinosaurs walked, the best approach is computer simulation. This is the only way of bringing together all the different strands of information we have on this dinosaur, so we can reconstruct how it once moved.”

Dr Lee Margetts, who also worked on the project, said: “We used the equivalent of 30,000 desktop computers to allow Argentinosaurus to take its first steps in over 94 million years. “The new study clearly demonstrates the dinosaur was more than capable of strolling across the Cretaceous planes of what is now Patagonia, South America.”

The team of scientists included Dr Rodolfo Coria from Carmen Funes Museum, Plaza Huincal, Argentina, who was behind the first physical reconstruction of this dinosaur that takes its name from the country where it was found. The dinosaur was so big it was named after a whole country.

Dr Phil Manning, from Manchester who contributed to the paper, said: “It is frustrating there was so little of the original dinosaur fossilized, making any reconstruction difficult. The digitization of such vast dinosaur skeletons using laser scanners brings Walking with Dinosaurs to life…this is science not just animation.”

Dr Sellers uses his own software (Gaitsym) to investigate locomotion both living and extinct animals have to overcome.

“The important thing is that these animals are not like any animal alive today and so we can’t just copy a modern animal,” he explained. “Our machine learning system works purely from the information we have on the dinosaur and predicts the best possible movement patterns.”

The dinosaur weighed 80 tonnes and the simulation shows that it would have reached just over 2 m/s — about 5 mph.

Dr Sellers said the research was important for understanding more about musculoskeletal systems and for developing robots.

He added: “All vertebrates from humans to fish share the same basic muscles, bones and joints. To understand how these function we can compare how they are used in different animals, and the most interesting are often those at extremes. Argentinosaurus is the biggest animal that ever walked on the surface of the Earth and understanding how it did this will tell us a lot about the maximum performance of the vertebrate musculoskeletal system. We need to know more about this to help understand how it functions in ourselves.

“Similarly if we want to build better legged robots then we need to know more about the mechanics of legs in a whole range of animals and nothing has bigger, more powerful legs than Argentinosaurus.”

The University of Manchester team now plans to use the method to recreate the steps of other dinosaurs including Triceratops, Brachiosaurus and T. rex.

Video :

Note : The above story is based on materials provided by University of Manchester. 

Paleozoic Era

The geological clock: a projection of Earth’s 4,5 Ga history on a clock Author: Woudloper Derivative work: Hardwigg Wikipedia

The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon, spanning from roughly 541 to 252.2 million years ago (ICS, 2004). It is the longest of the Phanerozoic eras, and is subdivided into six geologic periods (from oldest to least old): the Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian. The Paleozoic comes after the Neoproterozoic Era of the Proterozoic Eon, and is followed by the Mesozoic Era.
The Paleozoic was a time of dramatic geological, climatic, and evolutionary change. The Cambrian Period witnessed the most rapid and widespread diversification of life in Earth’s history, known as the Cambrian explosion, in which most modern phyla first appeared. Fish, arthropods, amphibians and reptiles all evolved during the Paleozoic. Life began in the ocean but eventually transitioned onto land, and by the late Paleozoic, it was dominated by various forms of organisms. Great forests of primitive plants covered the continents, many of which formed the coal beds of Europe and eastern North America. Towards the end of the era, large, sophisticated reptiles were dominant and the first modern plants (conifers) appeared.

The Paleozoic Era ended with the largest mass extinction in Earth’s history, the Permian–Triassic extinction event. The effects of this catastrophe were so devastating that it took life on land 30 million years into the Mesozoic to recover. Recovery of life in the sea may have been much faster.

Geology

In North America, the era began with deep sedimentary basins along the eastern, southeastern, and western sides of the continent, while the interior was dry land. As the era proceeded, the marginal seas periodically washed over the stable interior, leaving sedimentary deposits to mark their incursions. During the early part of the era, the area of exposed Precambrian, or shield, rocks in central Canada were eroding, supplying sediment to the basins from the interior. Beginning in the Ordovician Period, mountain building intermittently proceeded in the eastern part of the Appalachian region throughout the rest of the era, bringing in new sediments. Sediments washing from the Acadian Mountains filled the western part of the Appalachian basins to form the famous coal swamps of the Carboniferous Period. In North America carboniferous is not generally used instead the time is divided between Mississippian and Pennsylvanian period because of differences in the sedimentary rock deposited in this time. The Mississippian is characterized by limey sediments deposited in shallow seas, typically with abundant crinoidal fossils as in the Burlington fm. The Pennsylvanian typically is characterized by terrestrial sediments such as sands, shale and most importantly coal. Most of our oil and gas are obtained from Pennsylvanian sediments. Where this has been stripped, as in the Ozark domal region, oil is not typically available.

Paleoclimatic studies and evidence of glaciers indicate that central Africa was most likely in the polar regions during the early Paleozoic. During the early Paleozoic, the huge continent Gondwanaland had either formed or was forming. By mid-Paleozoic, the collision of North America and Europe produced the Acadian-Caledonian uplifts, and a subduction plate uplifted eastern Australia. By the late Paleozoic, continental collisions formed the supercontinent Pangaea and resulted in some of the great mountain chains, including the Appalachians, Urals, and mountains of Tasmania.

Tectonic activity

Land distribution early in the Paleozoic, around 540 Ma Author: Ron Blakey, NAU Geology

Geologically, the Paleozoic starts shortly after the breakup of a supercontinent called Pannotia. Throughout the early Paleozoic, the Earth’s landmass was broken up into a substantial number of continents. Towards the end of the era, the continents gathered together into a supercontinent called Pangaea, which included most of the Earth’s land area.

Climate

The Ordovician and Silurian periods were warm greenhouse periods, with the highest sea levels of the Paleozoic (200 m above today’s); the warm climate was interrupted only by a 30 million years cool period, the Early Palaeozoic Icehouse, culminating in the Hirnantian glaciation.
The early Cambrian climate was probably moderate at first, becoming warmer over the course of the Cambrian, as the second-greatest sustained sea level rise in the Phanerozoic got underway. However, as if to offset this trend, Gondwana moved south with considerable speed, so that, in Ordovician time, most of West Gondwana (Africa and South America) lay directly over the South Pole. The early Paleozoic climate was also strongly zonal, with the result that the “climate”, in an abstract sense became warmer, but the living space of most organisms of the time—the continental shelf marine environment—became steadily colder. However, Baltica (Northern Europe and Russia) and Laurentia (eastern North America and Greenland) remained in the tropical zone, while China and Australia lay in waters which were at least temperate. The Early Paleozoic ended, rather abruptly, with the short, but apparently severe, late Ordovician ice age. This cold spell caused the second-greatest mass extinction of Phanerozoic time. Over time, the warmer weather moved into the Paleozoic Era.

The middle Paleozoic was a time of considerable stability. Sea levels had dropped coincident with the ice age, but slowly recovered over the course of the Silurian and Devonian. The slow merger of Baltica and Laurentia, and the northward movement of bits and pieces of Gondwana created numerous new regions of relatively warm, shallow sea floor. As plants took hold on the continental margins, oxygen levels increased and carbon dioxide dropped, although much less dramatically. The north–south temperature gradient also seems to have moderated, or metazoan life simply became hardier, or both. At any event, the far southern continental margins of Antarctica and West Gondwana became increasingly less barren. The Devonian ended with a series of turnover pulses which killed off much of Middle Paleozoic vertebrate life, without noticeably reducing species diversity overall.

The late Paleozoic was a time which has left us a good many unanswered questions. The Mississippian began with a spike in atmospheric oxygen, while carbon dioxide plummeted to unheard-of lows. This destabilized the climate and led to one, and perhaps two, ice ages during the Carboniferous. These were far more severe than the brief Late Ordovician Ice; but, this time, the effects on world biota were inconsequential. By the Cisuralian, both oxygen and carbon dioxide had recovered to more normal levels. On the other hand, the assembly of Pangaea created huge arid inland areas subject to temperature extremes. The Lopingian is associated with falling sea levels, increased carbon dioxide and general climatic deterioration, culminating in the devastation of the Permian extinction.

Flora

An artist’s impression of early land plants

While macroscopic plant life appeared early in the Paleozoic and possibly late in the Neoproterozoic, it mostly remained aquatic until sometime in the Silurian and Devonian, when it began to transition onto dry land. Terrestrial flora reached its climax in the Carboniferous, when towering lycopsid rainforests dominated the tropical belt of Euramerica. Climate change caused the Carboniferous Rainforest Collapse which fragmented this habitat, diminishing the diversity of plant life in the late Carboniferous and Permian.

Fauna

A noteworthy feature of Paleozoic life is the sudden appearance of nearly all of the invertebrate animal phyla in great abundance at the beginning of the Cambrian. The first vertebrates appeared in the form of primitive fish, which greatly diversified in the Silurian and Devonian. The first animals to venture onto dry land were the arthropods. Some fish had lungs and strong, bony fins and could crawl onto the land also. The bones in their fins eventually evolved into legs and they became the first tetrapods. Amphibians were the dominant tetrapods until the mid-Carboniferous, when climate change greatly reduced their diversity. Later, reptiles prospered and continued to increase in number and variety by the late Permian.
Note : The above story is based on materials provided by Wikipedia

Paleontologist Presents Origin of Life Theory

Most researchers believe that life originated in deep-sea hydrothermal vents. About 4 billion years ago, Earth was a watery planet; ocean stretched from pole to pole; any life synthesis would be dilated. It needed a protected basin. (Credit: Image courtesy of Texas Tech University)

It has baffled humans for millennia: how did life begin on planet Earth? Now, new research from a Texas Tech University paleontologist suggests it may have rained from the skies and started in the bowels of hell.

Sankar Chatterjee, Horn Professor of Geosciences and curator of paleontology at The Museum of Texas Tech University believes he has found the answer by connecting theories on chemical evolution with evidence related to our planet’s early geology.

“This is bigger than finding any dinosaur,” Chatterjee said. “This is what we’ve all searched for – the Holy Grail of science.”

Thanks to regular and heavy comet and meteorite bombardment of Earth’s surface during its formative years 4 billion years ago, the large craters left behind not only contained water and the basic chemical building blocks for life, but also became the perfect crucible to concentrate and cook these chemicals to create the first simple organisms.

He will present his findings Oct. 30 during the 125th Anniversary Annual Meeting of the Geological Society of America in Denver.

As well as discovering how ancient animals flew, Chatterjee discovered the Shiva Meteorite Crater, which was created by a 25-mile-wide meteorite that struck off the coast of India. This research concluded this giant meteorite wreaked havoc simultaneously with the Chicxulub meteorite strike near Mexico, finishing the dinosaurs 65 million years ago.

Ironically, Chatterjee’s latest research suggests meteorites can be givers of life as well as takers. He said that meteor and comet strikes likely brought the ingredients and created the right conditions for life on our planet. By studying three sites containing the world’s oldest fossils, he believes he knows how the first single-celled organisms formed in hydrothermal crater basins.

“When the Earth formed some 4.5 billion years ago, it was a sterile planet inhospitable to living organisms,” Chatterjee said. “It was a seething cauldron of erupting volcanoes, raining meteors and hot, noxious gasses. One billion years later, it was a placid, watery planet teeming with microbial life – the ancestors to all living things.”

Recipe for Living

As the basins filled, volcanically driven geothermal vents heated the water and created convection. The result was constant water movement, creating a thick primordial soup. (Credit: Image courtesy of Texas Tech University)

“For may years, the debate on the origins of life centered on the chemical evolution of living cells from organic molecules by natural processes. Chatterjee said life began in four steps of increasing complexity – cosmic, geological, chemical and biological.

In the cosmic stage, a still-forming Earth and our solar system took a daily pounding from rocky asteroids and icy comets between 4.1 to 3.8 billion years ago. Plate tectonics, wind and water have hidden evidence of this early onslaught on our planet, but ancient craters on the surfaces of Mars, Venus, Mercury and our moon show just how heavy the meteorite showers once were.

Larger meteorites that created impact basins of about 350 miles in diameter inadvertently became the perfect crucibles, he said. These meteorites also punched through the Earth’s crust, creating volcanically driven geothermal vents. Also, they brought the basic building blocks of life that could be concentrated and polymerized in the crater basins.

After studying the environments of the oldest fossil-containing rocks on Earth in Greenland, Australia and South Africa, Chatterjee said these could be remnants of ancient craters and may be the very spots where life began in deep, dark and hot environments.

Because of Earth’s perfect proximity to the sun, the comets that crashed here melted into water and filled these basins with water and more ingredients. This gave rise to the geological stage. As these basins filled, geothermal venting heated the water and created convection, causing the water to move constantly and create a thick primordial soup.

“The geological stage provides special dark, hot, and isolated environments of the crater basins with the hydrothermal vent systems that served as incubators for life,” he said. “Segregation and concentration of organic molecules by convective currents took place here, something like the kinds we find on the ocean floor, but still very different. It was a bizarre and isolated world that would seem like a vision of hell with the foul smells of hydrogen sulfide, methane, nitric oxide and steam that provided life-sustaining energy.”

Then began the chemical stage, Chatterjee said. The heat churning the water inside the craters mixed chemicals together and caused simple compounds to grow into larger, more complex ones.

Protecting Important Information

Eventually, the first life forms left the confines of the crater and ventured into the newly formed oceans. (Credit: Image courtesy of Texas Tech University)

Most likely, pores and crevices on the crater basins acted as scaffolds for concentrations of simple RNA and protein molecules, he said. Unlike a popular theory that believes RNA came first and proteins followed, Chatterjee believes RNA and proteins emerged simultaneously and were encapsulated and protected from the environment.

“The dual origin of the ‘RNA/protein’ world is more plausible in the vent environments than the popular ‘RNA world,’” he said. “RNA molecules are very unstable. In vent environments, they would decompose quickly. Some catalysts, such as simple proteins, were necessary for primitive RNA to replicate and metabolize. On the other hand, amino acids, from which proteins are made, are easier to make than RNA components.”

The question remains how loose RNA and protein material floating in this soup protected itself in a membrane. Chatterjee believes University of California professor David Deamer’s hypothesis that membranous material existed in the primordial soup. Deamer isolated fatty acid vesicles from the Murchison meteorite that fell in 1969 in Australia. The cosmic fatty bubbles extracted from the meteorite mimic cell membranes.

“Meteorites brought this fatty lipid material to early Earth,” Chatterjee said. “This fatty lipid material floated on top of the water surface of crater basins but moved to the bottom by convection currents. At some point in this process during the course of millions of years, this fatty membrane could have encapsulated simple RNA and proteins together like a soap bubble. The RNA and protein molecules begin interacting and communicating. Eventually RNA gave way to DNA – a much more stable compound – and with the development of the genetic code, the first cells divided.”

The final stage – the biological stage – represents the origin of replicating cells as they began to store, process and transmit genetic information to their daughter cells, Chatterjee said. Infinite combinations took place, and countless numbers must have failed to function before the secret of replication was broken and the proper selection occurred.

“These self-sustaining first cells were capable of Darwinian evolution,” he said. “The emergence of the first cells on the early Earth was the culmination of a long history of prior chemical, geological and cosmic processes.”

Chatterjee also believes that modern RNA-viruses and protein-rich prions that cause deadly diseases probably represent the evolutionary legacy of primitive RNA and protein molecules. They may be the oldest cellular particles that predated the first cellular life. Once cellular life evolved, RNA-viruses and prions became redundant, but survived as parasites on the living cells.

The problem with theories on the origins of life is that they don’t propose any experiments that lead to the emergence of cells, Chatterjee said. However, he suggested an experiment to recreate the ancient prebiotic world and support or refute his theory.

“If future experiments with membrane-bound RNA viruses and prions result in the creation of a synthetic protocell, it may reflect the plausible pathways for the emergence of life on early Earth,” he said.

What: Paper No. 300-5: Impact, RNA-Protein World and the Endoprebiotic Origin of Life https://gsa.confex.com/gsa/2013AM/webprogram/Paper222699.html

Note : The above story is based on materials provided by Texas Tech University. The original article was written by John Davis. 

Looking for a new gold mine? We’ve got the map

Bill Griffin. The sub-continental lithospheric mantle (SCLM) makes up the “roots” of the oldest continents, down to 150-250 km. Over the 3 billion years since they formed, the margins of SCLM blocks have been chemically “refertilized”, and they effectively control the location of many types of ore deposits.

As published this month in Nature Geoscience, researchers and industry partners have produced the first major ‘cat scan of the earth’. Their work reveals a new chart of the sub-continental lithosphere mantle and its potential mineral hotspots, visible only through a set of newly integrated technologies.

“You hear the term ‘the next frontier’ dropped frequently in the world of research,” says Distinguished Professor Sue O’Reilly, Director of the ARC Centre of Excellence for Core to Crust Fluid Systems, “but to understand what’s happening below the earth is inherently more difficult to study than something like space exploration, or the human body – so it really is a new field, evolving with our technology.

“Using geochemical and geophysical technologies to explore layers of the earth, our research has for the first time mapped two-thirds of the world’s sub-continental lithosphere mantle, and analysed the chemical composition below – revealing potential mineral hotspots 100-200km under the surface.”

Traditionally, ore deposits have been discovered through surface prospecting, but as most surface-facing sites have now been identified, mineral exploration companies are seeking new insight as to where the earth’s magma plumes might deliver their rich mineral endowment next.

The Core to Crust team show how basic scientific research can work hand in hand with key industries to deliver new insight into the earth’s architecture and evolution. The technological mix developed by the team has already had an impact on Australia’s mineral exploration industry, changing exploration strategies for a significant part of the industry by providing this new predictive framework for a range of economic deposits.

“Our earliest understandings of the lithosphere suggested that it was a smooth, consistent layer of the earth’s upper mantle, says O’Reilly. “Modern geophysical imaging shows otherwise – and we suggest that it is, in fact, a layer with many irregularities – and it’s in these sites that potential new mineral sources are lying in wait.”

To identify a new source, the team’s predictive framework analyses the chemical composition of the upper mantle in a location, to judge its metal endowment potential, the architecture of the lithosphere in that location and the geological precedents of similar areas.

“Pulling together information from international datasets of the last decade, including over 40,000 new geochemical analyses from the Macquarie laboratories, the study has revealed amazing secrets about the way the world works, how it has evolved, and now, a new predictive model for minerals exploration. We see the deep earth beneath the surface in four dimensions: height, width, depth, and time,” said O’Reilly.

“This is a textbook illustration of synergy between pure and strategic research – the work has revealed new fundamental information about the origin of the uppermost 200km shell of the Earth over 3.5 billion years, and is has provided the exploration industry with a new framework for global-scale exploration targeting.”

Note : The above story is based on materials provided by Macquarie University

Researchers quantify toxic ocean conditions during major extinction 93.9 million years ago

Credit: NASA

RIVERSIDE, Calif. — Oxygen in the atmosphere and ocean rose dramatically about 600 million years ago, coinciding with the first proliferation of animal life. Since then, numerous short lived biotic events — typically marked by significant climatic perturbations — took place when oxygen concentrations in the ocean dipped episodically.

The most studied and extensive of these events occurred 93.9 million years ago. By looking at the chemistry of rocks deposited during that time period, specifically coupled carbon and sulfur isotope data, a research team led by University of California, Riverside biogeochemists reports that oxygen-free and hydrogen sulfide-rich waters extended across roughly five percent of the global ocean during this major climatic perturbation — far more than the modern ocean’s 0.1 percent but much less than previous estimates for this event.

The research suggests that previous estimates of oxygen-free and hydrogen sulfide-rich conditions, or “euxinia,” were too high. Nevertheless, the limited and localized euxinia were still sufficiently widespread to have dramatic effect on the entire ocean’s chemistry and thus biological activity.

“These conditions must have impacted nutrient availability in the ocean and ultimately the spatial and temporal distribution of marine life,” said team member Jeremy D. Owens, a former UC Riverside graduate student, who is now a postdoctoral scientist at the Woods Hole Oceanographic Institution. “Under low-oxygen environments, many biologically important metals and other nutrients are removed from seawater and deposited in the sediments on the seafloor, making them less available for life to flourish.”

“What makes this discovery particularly noteworthy is that we mapped out a landscape of bioessential elements in the ocean that was far more perturbed than we expected, and the impacts on life were big,” said Timothy W. Lyons, a professor of biogeochemistry at UCR, Owens’s former advisor and the principal investigator on the research project.

Study results appear online this week in the Proceedings of the National Academy of Sciences.

Across the event 93.9 million years ago, a major biological extinction in the marine realm has already been documented. Also associated with this event are high levels of carbon dioxide in the atmosphere, which are linked to elevated ocean and atmospheric temperatures. Associated consequences include likely enhanced global rainfall and weathering of the continents, which further shifted the chemistry of the ocean.

“Our work shows that even though only a small portion of the ocean contained toxic and metal-scavenging hydrogen sulfide, it was sufficiently large so that changes to the ocean’s chemistry and biology were likely profound,” Owens said. “What this says is that only portions of the ocean need to contain sulfide to greatly impact biota.”

For their analysis, the researchers collected seafloor mud samples, now rock, from multiple localities in England and Italy. They then performed chemical extraction on the samples to analyze the sulfur isotope compositions in order to estimate the chemistry of the global ocean.

According to the researchers, the importance of their study is elevated by the large amount of previous work on the same interval and thus the extensive availability of supporting data and samples. Yet despite all this past research, the team was able to make a fundamental discovery about the global conditions in the ancient ocean and their impacts on life.

“Today, we are facing rising carbon dioxide contents in the atmosphere through human activities, and the amount of oxygen in the ocean may drop correspondingly in the face of rising seawater temperatures,” Lyons said. “Oxygen is less soluble in warmer water, and there are already suggestions of such decreases. In the face of these concerns, our findings from the warm, oxygen-poor ancient ocean may be a warning shot about yet another possible perturbation to marine ecology in the future.”

Note : The above story is based on materials provided by University of California – Riverside

Tell-Tale Toes Point to Oldest-Known Fossil Bird Tracks from Australia

The Cretaceous bird tracks were found on a slab of sandstone. (Credit: Photo by Alan Tait)

Two fossilized footprints found at Dinosaur Cove in Victoria, Australia, were likely made by birds during the Early Cretaceous, making them the oldest known bird tracks in Australia.

The journal Palaeontology is publishing an analysis of the footprints led by Anthony Martin, a paleontologist at Emory University in Atlanta who specializes in trace fossils, which include tracks, burrows and nests. The study was co-authored by Patricia Vickers-Rich and Michael Hall of Monash University in Victoria and Thomas Rich of the Museum Victoria in Melbourne.

Much of the rocky coastal strata of Dinosaur Cove in southern Victoria were formed in river valleys in a polar climate during the Early Cretaceous. A great rift valley formed as the ancient supercontinent Gondwana broke up and Australia separated from Antarctica.

“These tracks are evidence that we had sizeable, flying birds living alongside other kinds of dinosaurs on these polar, river floodplains, about 105 million years ago,” Martin says.

The thin-toed tracks in fluvial sandstone were likely made by two individual birds that were about the size of a great egret or a small heron, Martin says. Rear-pointing toes helped distinguish the tracks as avian, as opposed to a third nearby fossil track that was discovered at the same time, made by a non-avian theropod.

A long drag mark on one of the two bird tracks particularly interested Martin.

“I immediately knew what it was — a flight landing track — because I’ve seen many similar tracks made by egrets and herons on the sandy beaches of Georgia,” Martin says.

Martin often leads student field trips to Georgia’s coast and barrier islands, where he studies modern-day tracks and other life traces, to help him better identify fossil traces.

The ancient landing track from Australia “has a beautiful skid mark from the back toe dragging in the sand, likely caused as the bird was flapping its wings and coming in for a soft landing,” Martin says. Fossils of landing tracks are rare, he adds, and could add to our understanding of the evolution of flight.

Today’s birds are actually modern-day dinosaurs, and share many characteristics with non-avian dinosaurs that went extinct, such as nesting and burrowing. (Martin previously discovered the trace fossils of non-avian dinosaur burrows, including at a site along the coast of Victoria.)

The theropod carnivore Tyrannosaurus rex had a vestigial rear toe, evidence that T. rex shared a common ancestor with birds. “In some dinosaur lineages, that rear toe got longer instead of shorter and made a great adaptation for perching up in trees,” Martin says. “Tracks and other trace fossils offer clues to how non-avian dinosaurs and birds evolved and started occupying different ecological niches.”

Dinosaur Cove has yielded a rich trove of non-avian dinosaur bones from dozens of species, but only one

A drag mark made by the rear toe on one of the Cretaceous bird tracks indicates that it was a flight landing track. Credit: Photo by Anthony Martin

skeletal piece of a bird — a fossilized wishbone — has been found in the Cretaceous rocks of Victoria.

Martin spotted the first known dinosaur trackway of Victoria in 2010 and a few other tracks have been discovered since then. Volunteers working in Dinosaur Cove found these latest tracks on a slab of rock, and Martin later analyzed them.

The tracks were made on the moist sand of a river bank, perhaps following a polar winter, after spring and summer flood waters had subsided, Martin says. “The biggest question for me,” he adds, “is whether the birds that made these tracks lived at the site during the polar winter, or migrated there during the spring and summer.”

One of the best records of the dinosaur-bird connection has come from discoveries in Liaoning province of Northeastern China, including fossils of non-avian dinosaurs with feathers. Samples of amber have also been found in Liaoning, containing preserved feathers from both birds and non-avian dinosaurs going back to the Cretaceous.

“In contrast, the picture of early bird evolution in the Southern Hemisphere is mostly incomplete,” Martin says, “but with these tracks, it just got a little better.”

Note : The above story is based on materials provided by Emory Health Sciences, via EurekAlert!, a service of AAAS. 

Proterozoic Eon

The geological clock: a projection of Earth’s 4,5 Ga history on a clock Author: Woudloper Derivative work: Hardwigg Wikipedia

The Proterozoic is a geological eon representing the time just before the proliferation of complex life on Earth. The name Proterozoic comes from Greek and means “earlier life”. The Proterozoic Eon extended from 2,500 Ma to 542.0±1.0 Ma (million years ago), and is the most recent part of the informally named “Precambrian” time. It is subdivided into three geologic eras (from oldest to youngest): the Paleoproterozoic, Mesoproterozoic, and Neoproterozoic.
The well-identified events of this eon were the transition to an oxygenated atmosphere during the Mesoproterozoic; several glaciations, including the hypothesized Snowball Earth during the Cryogenian period in the late Neoproterozoic; and the Ediacaran Period (635 to 542 Ma) which is characterized by the evolution of abundant soft-bodied multicellular organisms.

The Proterozoic record

The geologic record of the Proterozoic is much better than that for the preceding Archean. In contrast to the deep-water deposits of the Archean, the Proterozoic features many strata that were laid down in extensive shallow epicontinental seas; furthermore, many of these rocks are less metamorphosed than Archean-age ones, and plenty are unaltered. Study of these rocks shows that the eon continued the massive continental accretion that had begun late in the Archean, as well as featured the first definitive supercontinent cycles and wholly modern orogenic activity
The first known glaciations occurred during the Proterozoic; one began shortly after the beginning of the eon, while there were at least four during the Neoproterozoic, climaxing with the Snowball Earth of the Sturtian and Marinoan glaciations.

The accumulation of oxygen

One of the most important events of the Proterozoic was the accumulation of oxygen in the Earth’s atmosphere. Though oxygen is believed to have been released by photosynthesis as far back as Archean times, it could not build up to any significant degree until chemical sinks — unoxidized sulfur and iron — had been filled; until roughly 2.3 billion years ago, oxygen was probably only 1% to 2% of its current level. Banded iron formations, which provide most of the world’s iron ore, were also a prominent chemical sink; their accumulation ceased after 1.9 billion years ago, either due to an increase in oxygen or a more thorough mixing of the oceanic water column.

Red beds, which are colored by hematite, indicate an increase in atmospheric oxygen after 2 billion years ago; they are not found in older rocks. The oxygen buildup was probably due to two factors: a filling of the chemical sinks, and an increase in carbon burial, which sequestered organic compounds that would have otherwise been oxidized by the atmosphere.

Paleogeography and tectonics

Throughout the history of the Earth, there have been times when the continental mass came together to form a supercontinent, followed by the break-up of the supercontinent and new continents moving apart again. This repetition of tectonic events is called a Wilson cycle. It is at least clear that, about 1,000–830 Ma, most continental mass was united in the supercontinent Rodinia. Rodinia was not the first supercontinent; it formed at about 1.0 Ga by accretion and collision of fragments produced by breakup of the older supercontinent, called Nuna or Columbia, which was assembled by global-scale 2.0–1.8 Ga collisional events. This means plate tectonic processes similar to today’s must have been active during the Proterozoic.

After the break-up of Rodinia about 800 Ma, it is possible the continents joined again around 550 Ma. The hypothetical supercontinent is sometimes referred to as Pannotia or Vendia. The evidence for it is a phase of continental collision known as the Pan-African orogeny, which joined the continental masses of current-day Africa, South America, Antarctica and Australia. It is extremely likely, however, that the aggregation of continental masses was not completed, since a continent called Laurentia (roughly equivalent to current-day North America) had already started breaking off around 610 Ma. It is at least certain that by the end of the Proterozoic eon, most of the continental mass lay united in a position around the south pole.

Life

Lower Proterozoic stromatolites from Bolivia, South America

The first advanced single-celled, eukaryotes and multi-cellular life, Francevillian Group Fossils, roughly

The blossoming of eukaryotes such as acritarchs did not preclude the expansion of cyanobacteria; in fact, stromatolites reached their greatest abundance and diversity during the Proterozoic, peaking roughly 1200 million years ago.

coincides with the start of the accumulation of free oxygen. This may have been due to an increase in the oxidized nitrates that eukaryotes use, as opposed to cyanobacteria. It was also during the Proterozoic that the first symbiotic relationships between mitochondria (for nearly all eukaryotes) and chloroplasts (for plants and some protists only) and their hosts evolved.

Classically, the boundary between the Proterozoic and the Phanerozoic eons was set at the base of the Cambrian period when the first fossils of animals including trilobites and archeocyathids appeared. In the second half of the 20th century, a number of fossil forms have been found in Proterozoic rocks, but the upper boundary of the Proterozoic has remained fixed at the base of the Cambrian, which is currently placed at 542 Ma.
Note : The above story is based on materials provided by Wikipedia

Bees Underwent Massive Extinctions When Dinosaurs Did

A small carpenter bee. (Credit: Sandra Rehan)

For the first time ever, scientists have documented a widespread extinction of bees that occurred 65 million years ago, concurrent with the massive event that wiped out land dinosaurs and many flowering plants. Their findings, published this week in the journal PLOS ONE, could shed light on the current decline in bee species.

Lead author Sandra Rehan, an assistant professor of biological sciences at UNH, worked with colleagues Michael Schwarz at Australia’s Flinders University and Remko Leys at the South Australia Museum to model a mass extinction in bee group Xylocopinae, or carpenter bees, at the end of the Cretaceous and beginning of the Paleogene eras, known as the K-T boundary.

Previous studies have suggested a widespread extinction among flowering plants at the K-T boundary, and it’s long been assumed that the bees who depended upon those plants would have met the same fate. Yet unlike the dinosaurs, “there is a relatively poor fossil record of bees,” says Rehan, making the confirmation of such an extinction difficult.

Rehan and colleagues overcame the lack of fossil evidence for bees with a technique called molecular phylogenetics. Analyzing DNA sequences of four “tribes” of 230 species of carpenter bees from every continent except Antarctica for insight into evolutionary relationships, the researchers began to see patterns consistent with a mass extinction. Combining fossil records with the DNA analysis, the researchers could introduce time into the equation, learning not only how the bees are related but also how old they are.

“The data told us something major was happening in four different groups of bees at the same time,” says Rehan, of UNH’s College of Life Sciences and Agriculture. “And it happened to be the same time as the dinosaurs went extinct.”

While much of Rehan’s work involves behavioral observation of bees native to the northeast of North America, this research taps the computer-heavy bioinformatics side of her research, assembling genomic data to elucidate similarities and differences among the various species over time. Marrying observations from the field with genomic data, she says, paints a fuller picture of these bees’ behaviors over time.

“If you could tell their whole story, maybe people would care more about protecting them,” she says. Indeed, the findings of this study have important implications for today’s concern about the loss in diversity of bees, a pivotal species for agriculture and biodiversity.

“Understanding extinctions and the effects of declines in the past can help us understand the pollinator decline and the global crisis in pollinators today,” Rehan says.

The article, “First evidence for a massive extinction event affecting bees close to the K-T boundary,” was published in the Oct. 23, 2013 edition of PLOS ONE. Funding for the research was provided by Endeavour Research Fellowships (Rehan) and Australian Research Council Discovery Grants (Schwarz).

The University of New Hampshire, founded in 1866, is a world-class public research university with the feel of a New England liberal arts college. A land, sea, and space-grant university, UNH is the state’s flagship public institution, enrolling 12,300 undergraduate and 2,200 graduate students.

Note : The above story is based on materials provided by University of New Hampshire.

Reading Ancient Climate from Plankton Shells

The intricate structure of plankton shells provides new opportunities to chart complex changes in climate. (Credit: Oscar Branson, University of Cambridge)
The intricate structure of plankton shells provides new opportunities to chart complex changes in climate. (Credit: Oscar Branson, University of Cambridge)

Climate changes from millions of years ago are recorded at daily rate in ancient sea shells, new research shows.

A huge X-ray microscope has revealed growth bands in plankton shells that show how shell chemistry records the sea temperature.

The results could allow scientists to chart short timescale changes in ocean temperatures hundreds of millions of years ago.

Plankton shells show features like tree rings, recording historical climate.

It’s important to understand current climate change in the light of how climate has varied in the geological past. One way to do this, for the last few thousand years, is to analyse ice from the poles. The planet’s temperature and atmosphere are recorded by bubbles of ancient air trapped in polar ice cores. The oldest Antarctic ice core records date back to around 800,000 years ago.

Results just published in the journal Earth and Planetary Sciences Letters reveal how ancient climate change, pushing back hundreds of millions of years ago into deep time, is recorded by the shells of oceanic plankton.

As microbial plankton grow in ocean waters, their shells, made of the mineral calcite, trap trace amounts of chemical impurities, maybe only a few atoms in a million getting replaced by impurity atoms. Scientists have noticed that plankton growing in warmer waters contain more impurities, but it has not been clear how and why this “proxy” for temperature works.

When the plankton die, they fall to the muddy ocean floor, and can be recovered today from that muddy ocean floor sediments, which preserve the shells as they are buried. The amount of impurity, measured in fossil plankton shells, provides a record of past ocean temperature, dating back more than 100 million years ago.

Now, researchers from the Department of Earth Sciences at the University of Cambridge have measured traces of magnesium in the shells of plankton using an X-ray microscope in Berkeley, California, at the “Advanced Light Source” synchrotron — a huge particle accelerator that generates X-rays to study matter in minuscule detail.

The powerful X-ray microscope has revealed narrow nanoscale bands in the plankton shell where the amount of magnesium is very slightly higher, at length scales as small as one hundredth that of a human hair. They are growth bands, rather like tree rings, but in plankton the bands occur daily or so, rather than yearly.

“These growth bands in plankton show the day by day variations in magnesium in the shell at a 30 nanometre length scale. For slow-growing plankton it opens the way to seeing seasonal variations in ocean temperatures or plankton growth in samples dating back tens to hundreds of millions of years,” says Professor Simon Redfern, one of the experimenters on the project.

“Our X-ray data show that the trace magnesium sits inside the crystalline mineral structure of the plankton shell. That’s important because it validates previous assumptions about using magnesium contents as a measure of past ocean temperature.”

The chemical environment of the trace elements in the plankton shell, revealed in the new measurements, shows that the magnesium sits in calcite crystal replacing calcium, rather than in microbial membranes in their impurities in the shell. This helps explain why temperature affects the chemistry of plankton shells — warmer waters favour increased magnesium in calcite.

The group are now using the UK’s “Diamond” synchrotron X-ray facility to measure how plankton shells grow and whether they change at all in the ocean floor sediments. Their latest results could allow scientists to establish climate variability in Earth’s far distant past, as well as providing new routes to measure ocean acidification and salinity in past oceans.

Note : The above story is based on materials provided by University of Cambridge, via EurekAlert!, a service of AAAS. The original story is licensed under a Creative Commons Licence.

Study shows unprecedented warmth in Arctic

University of Colorado Boulder Professor Gifford Miller is shown here collecting dead plant samples from the edge of a Baffin Island ice cap. (Credit: University of Colorado)

The heat is on, at least in the Arctic. Average summer temperatures in the Eastern Canadian Arctic during the last 100 years are higher now than during any century in the past 44,000 years and perhaps as long ago as 120,000 years, says a new University of Colorado Boulder study.

 

>The study is the first direct evidence the present warmth in the Eastern Canadian Arctic exceeds the peak warmth there in the Early Holocene, when the amount of the sun’s energy reaching the Northern Hemisphere in summer was roughly 9 percent greater than today, said CU-Boulder geological sciences Professor Gifford Miller, study leader. The Holocene is a geological epoch that began after Earth’s last glacial period ended roughly 11,700 years ago and which continues today.

Miller and his colleagues used dead moss clumps emerging from receding ice caps on Baffin Island as tiny clocks. At four different ice caps, radiocarbon dates show the mosses had not been exposed to the elements since at least 44,000 to 51,000 years ago.

Since radiocarbon dating is only accurate to about 50,000 years and because Earth’s geological record shows it was in a glaciation stage prior to that time, the indications are that Canadian Arctic temperatures today have not been matched or exceeded for roughly 120,000 years, Miller said.

“The key piece here is just how unprecedented the warming of Arctic Canada is,” said Miller, also a fellow at CU-Boulder’s Institute of Arctic and Alpine Research. “This study really says the warming we are seeing is outside any kind of known natural variability, and it has to be due to increased greenhouse gases in the atmosphere.”

A paper on the subject appeared online Oct. 21 in Geophysical Research Letters, a journal published by the American Geophysical Union. Co-authors include CU-Boulder Senior Research Associate Scott Lehman, former CU-Boulder doctoral student and now Prescott College Professor Kurt Refsnider, University of California Irvine researcher John Southon and University of Wisconsin, Madison Research Associate Yafang Zhong. The National Science Foundation provided the primary funding for the study.

Miller and his colleagues compiled the age distribution of 145 radiocarbon-dated plants in the highlands of Baffin Island that were exposed by ice recession during the year they were collected by the researchers. All samples collected were within 1 meter of the ice caps, which are generally receding by 2 to 3 meters a year. “The oldest radiocarbon dates were a total shock to me,” said Miller.

Located just east of Greenland, the 196,000-square-mile Baffin Island is the fifth largest island in the world. Most of it lies above the Arctic Circle. Many of the ice caps on the highlands of Baffin Island rest on relatively flat terrain, usually frozen to their beds. “Where the ice is cold and thin, it doesn’t flow, so the ancient landscape on which they formed is preserved pretty much intact,” said Miller.

To reconstruct the past climate of Baffin Island beyond the limit of radiocarbon dating, Miller and his team used data from ice cores previously retrieved by international teams from the nearby Greenland Ice Sheet.

The ice cores showed that the youngest time interval from which summer temperatures in the Arctic were plausibly as warm as today is about 120,000 years ago, near the end of the last interglacial period. “We suggest this is the most likely age of these samples,” said Miller.

The new study also showed summer temperatures cooled in the Canadian Arctic by about 5 degrees Fahrenheit from roughly 5,000 years ago to about 100 years ago — a period that included the Little Ice Age from 1275 to about 1900.

“Although the Arctic has been warming since about 1900, the most significant warming in the Baffin Island region didn’t really start until the 1970s,” said Miller. “And it is really in the past 20 years that the warming signal from that region has been just stunning. All of Baffin Island is melting, and we expect all of the ice caps to eventually disappear, even if there is no additional warming.”

Temperatures across the Arctic have been rising substantially in recent decades as a result of the buildup of greenhouse gases in Earth’s atmosphere. Studies by CU-Boulder researchers in Greenland indicate temperatures on the ice sheet have climbed 7 degrees Fahrenheit since 1991.

A 2012 study by Miller and colleagues using radiocarbon-dated mosses that emerged from under the Baffin Island ice caps and sediment cores from Iceland suggested that the trigger for the Little Ice Age was likely a combination of exploding tropical volcanoes — which ejected tiny aerosols that reflected sunlight back into space — and a decrease in solar radiation.

Note : The above story is based on materials provided by University of Colorado at Boulder.

Archean Eon

The geological clock: a projection of Earth’s 4,5 Ga history on a clock (“MA” = a million years (Megayear) ago; “GA” = a billion years (Gigayear) ago) Author: Woudloper Derivative work: Hardwigg Wikipedia

The Archean  is a geologic eon before the Proterozoic Eon, before 2.5 Ga (billion years), or 2,500 million years ago.

Classification issues

Instead of being based on stratigraphy as all other geological ages are, the beginning of the Archean eon is defined chronometrically. The lower boundary (starting point) of 4 billion years is officially recognized by the International Commission on Stratigraphy.

The Archean customarily starts at 4 Ga—at the end of the Hadean Eon. In older literature, the Hadean is included as part of the Archean. The name comes from the ancient Greek Αρχή (Arkhē), meaning “beginning, origin”.

Earth

The Archean is one of the four principal eons of Earth history. When the Archean began, the Earth’s heat flow was nearly three times as high as it is today, and it was still twice the current level at the transition from the Archean to the Proterozoic (2,500 Ma). The extra heat was the result of a mix of remnant heat from planetary accretion, heat from the formation of the Earth’s core, and heat produced by radioactive elements.

Most surviving Archean rocks are metamorphic or igneous. Volcanic activity was considerably higher than today, with numerous lava eruptions, including unusual types such as komatiite. Granitic rocks predominate throughout the crystalline remnants of the surviving Archean crust. Examples include great melt sheets and voluminous plutonic masses of granite, diorite, layered intrusions, anorthosites and monzonites known as sanukitoids.

The Earth of the early Archean may have supported a tectonic regime unlike that of the present. Some scientists argue that, because the Earth was much hotter, tectonic activity was more vigorous than it is today, resulting in a much faster rate of recycling of crustal material. This may have prevented cratonisation and continent formation until the mantle cooled and convection slowed down. Others argue that the oceanic lithosphere was too buoyant to subduct, and that the rarity of Archean rocks is a function of erosion by subsequent tectonic events. The question of whether plate tectonic activity existed in the Archean is an active area of modern research.

There are two schools of thought concerning the amount of continental crust that was present in the Archean. One school maintains that no large continents existed until late in the Archean: small protocontinents were the norm, prevented from coalescing into larger units by the high rate of geologic activity. The other school follows the teaching of Richard Armstrong, who argued that the continents grew to their present volume in the first 500 million years of Earth history and have maintained a near-constant ever since: throughout most of Earth history, recycling of continental material crust back to the mantle in subduction or collision zones balances crustal growth.

Opinion is also divided about the mechanism of continental crustal growth. Those scientists who doubt that plate tectonics operated in the Archean argue that the felsic protocontinents formed at hotspots rather than subduction zones. Through a process called “sagduction”, which refers to partial melting in downward-directed diapirs, a variety of mafic magmas produce intermediate and felsic rocks. Others accept that granite formation in island arcs and convergent margins was part of the plate tectonic process, which has operated since at least the start of the Archean.

An explanation for the general lack of Hadean rocks (older than 3800 Ma) is the efficiency of the processes that either cycled these rocks back into the mantle or effaced any isotopic record of their antiquity. All rocks in the continental crust are subject to metamorphism, partial melting and tectonic erosion during multiple orogenic events and the chance of survival at the surface decreases with increasing age. In addition, a period of intense meteorite bombardment in the period 4.0-3.8 Ga pulverized all rocks at the Earth’s surface during the period. Some think that the similar age of the oldest surviving rocks and the “late heavy bombardment” is not coincidental.

Palaeoenvironment

The Archean atmosphere is thought to have nearly lacked free oxygen. Astronomers think that the sun had about 70–75% of the present luminosity, yet temperatures appear to have been near modern levels even within 500 Ma of Earth’s formation, which is puzzling (the faint young sun paradox). The presence of liquid water is evidenced by certain highly deformed gneisses produced by metamorphism of sedimentary protoliths. The equable temperatures may reflect the presence of larger amounts of greenhouse gases than later in the Earth’s history. Alternatively, Earth’s albedo may have been lower at the time, due to less land area and cloud cover.

By the end of the Archaean c. 2500 Ma (million years ago), plate tectonic activity may have been similar to that of the modern Earth. There are well-preserved sedimentary basins, and evidence of volcanic arcs, intracontinental rifts, continent-continent collisions and widespread globe-spanning orogenic events suggesting the assembly and destruction of one and perhaps several supercontinents. Liquid water was prevalent, and deep oceanic basins are known to have existed by the presence of banded iron formations, chert beds, chemical sediments and pillow basalts.

Geology

Although a few mineral grains are known that are Hadean, the oldest rock formations exposed on the surface of the Earth are Archean or slightly older. Archean rocks are known from Greenland, the Canadian Shield, the Baltic Shield, Scotland, India, Brazil, western Australia, and southern Africa. Although the first continents formed during this eon, rock of this age makes up only 7% of the world’s current cratons; even allowing for erosion and destruction of past formations, evidence suggests that continental crust equivalent to only 5-40% of the present amount formed during the Archean.

In contrast to Proterozoic rocks, Archean rocks are often heavily metamorphized deep-water sediments, such as graywackes, mudstones, volcanic sediments, and banded iron formations. Carbonate rocks are rare, indicating that the oceans were more acidic due to dissolved carbon dioxide than during the Proterozoic.Greenstone belts are typical Archean formations, consisting of alternating units of metamorphosed mafic igneous and sedimentary rocks. The meta-igneous rocks were derived from volcanic island arcs, while the metasediments represent deep-sea sediments eroded from the neighboring island arcs and deposited in a forearc basin. Greenstone belts represent sutures between protocontinents.

Life

Fossils of cyanobacterial mats (stromatolites, which were instrumental in creating the free oxygen in the atmosphere ) are found throughout the Archean, becoming especially common late in the eon, while a few probable bacterial fossils are known from chert beds. In addition to the domain Bacteria (once known as Eubacteria), microfossils of the domain Archaea have also been identified.

Life was probably present throughout the Archean, but may have been limited to simple non-nucleated single-celled organisms, called Prokaryota (formerly known as Monera). There are no known eukaryotic fossils, though they might have evolved during the Archean without leaving any fossils. No fossil evidence has been discovered for ultramicroscopic intracellular replicators such as viruses.

Note : The above story is based on materials provided by Wikipedia

High School Student Discovers Skeleton of Baby Dinosaur

This is the skeleton of the baby Parasaurolophus nicknamed “Joe.” Credit: Raymond M. Alf Museum of Paleontology

Claremont, CA – A chance find by a high school student led to the youngest, smallest and most complete fossil skeleton yet known from the iconic tube-crested dinosaur Parasaurolophus. The discovery, announced today by the Raymond M. Alf Museum of Paleontology at The Webb Schools, shows that the prehistoric plant-eater sprouted its strange headgear before it celebrated its first birthday. Three-dimensional scans of nearly the entire fossil are freely available online, making this the most digitally-accessible dinosaur to date.

The fossil skeleton was discovered in 2009 by high school student Kevin Terris, within Grand Staircase-Escalante National Monument in southern Utah. Incredibly, the specimen was missed by two professional paleontologists, who walked within several feet of the exposed bones days prior to the discovery. “At first I was interested in seeing what the initial piece of bone sticking out of the rock was,” commented Terris. “When we exposed the skull, I was ecstatic!” Excavation and subsequent cleaning of the fossil, nicknamed “Joe” after a long-time supporter of the Alf Museum whose family funded preparation of the fossil, revealed nearly the entire skeleton of a baby dinosaur measuring only six feet long when it died.

Detailed study of the skeleton of “Joe” identified it as the most complete specimen yet known for Parasaurolophus (pronounced PAIR-uh-SORE-AH-luf-us), a duck-billed (hadrosaurid) dinosaur that lived throughout western North America around 75 million years ago. The herbivore is notable for a long and hollow bony tube on the top of its skull, which scientists speculate was used like a trumpet to blast sound for communication, as well as a billboard for visual display. Although partial skulls and skeletons of full-grown Parasaurolophus have been known for over 90 years, scientists previously knew little about how Parasaurolophus grew up.

Intriguingly, the new fossil shows that baby Parasaurolophus had a low bump on top of its head, which only later morphed into the curved tube of adults. “Our baby Parasaurolophus is barely one-quarter of adult size, but it had already started growing its crest,” stated lead project scientist Andrew Farke, who is Augustyn Family Curator at the Raymond M. Alf Museum of Paleontology. “This is surprising, because related dinosaurs didn’t sprout their ornamentation until they were at least half-grown. Parasaurolophus had to get an early start in order to form its unique headgear.”

A sample of bone from the leg helped estimate the animal’s age at death. “Dinosaurs have yearly growth rings in their bone tissue, like trees. But we didn’t see even one ring. That means it grew to a quarter of adult size in less than a year,” commented co-author Sarah Werning of Stony Brook University. Although “Joe” was only six feet long and a year old, it would have grown to 25 feet in length as an adult.

The fossil skeleton has yielded a world of previously unknown information about Parasaurolophus and its relatives. Medical scans documented the internal anatomy of the animal’s skull, allowing a reconstruction of its vocal capabilities. “If adult Parasaurolophus had ‘woofers,’ the babies had ‘tweeters.’ The short and small crest of baby ‘Joe’ shows that it may have had a much higher pitch to its call than did adults,” stated Andrew Farke. “Along with the visual differences, this might have helped animals living in the same area to figure out who was the big boss.”

Because of the broad importance of the fossil, researchers have made 3D digital scans of the entire fossil freely available on-line (links via http://www.dinosaurjoe.com). Although portions of other dinosaur fossils have been scanned and distributed in this way before, this the first time that virtually an entire skeleton has been posted. This will allow scientists and the public alike unparalleled access to this fossil.

This image shows a comparison of the size of the baby Parasaurolophus (green) to adult Parasaurolophus, as well as an adult and baby human. Credit: Scott Hartman, Matt Martyniuk, and Raymond M. Alf Museum of Paleontology

The study describing the new fossil was published today in the open access scientific journal PeerJ (meaning that anyone can read and download the article for free, and without restrictions). Additionally, the specimen is now on exhibit at the Raymond M. Alf Museum of Paleontology in Claremont, California. Researchers who co-authored the study include Andrew Farke (Raymond M. Alf Museum of Paleontology, Claremont, California), Sarah Werning (University of California Museum of Paleontology, Berkeley, and Stony Brook University, New York), and high school students Derek Chok, Annisa Herrero, and Brandon Scolieri (The Webb Schools, Claremont, California). The fossil was collected under a permit from Grand Staircase-Escalante National Monument and the Bureau of Land Management, Utah.

Video :

Note : The above story is based on materials provided by Raymond M. Alf Museum of Paleontology, via EurekAlert!, a service of AAAS. 

Quake-triggered landslides pose significant hazard for Seattle, new study details potential damage

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Locations of each zoom-in are shown on the map of Seattle at right. A) Coastal bluffs in the northern part of Seattle are most affected when soils are saturated. B) There are several areas along the I-5 corridor that are highly susceptible to landsliding for all soil saturation levels, such as the area shown here near the access point to the West Seattle bridge. C) The hillsides in West Seattle along the Duwamish valley are at risk of seismically induced landsliding, such as the area shown here. There are industrial as well as 59 residential buildings that could be affected by runout from landsliding in these areas. D) The coastal bluffs along Puget Sound in West Seattle on the hanging wall of the fault, such as the area shown here, are the most highly susceptible areas to landsliding in the city; numerous residential structures are at risk from both potential landslide source areas and runout.Credit: Allstadt/BSSA

SAN FRANCISCO — SAN FRANCISCO — A new study suggests the next big quake on the Seattle fault may cause devastating damage from landslides, greater than previously thought and beyond the areas currently defined as prone to landslides. Published online Oct. 22 by the Bulletin of the Seismological Society of America (BSSA), the research offers a framework for simulating hundreds of earthquake scenarios for the Seattle area.

“A major quake along the Seattle fault is among the worst case scenarios for the area since the fault runs just south of downtown. Our study shows the need for dedicated studies on seismically induced landsliding” said co-author Kate Allstadt, doctoral student at University of Washington.

Seattle is prone to strong shaking as it sits atop the Seattle Basin – a deep sedimentary basin that amplifies ground motion and generates strong seismic waves that tend to increase the duration of the shaking. The broader region is vulnerable to earthquakes from multiple sources, including deep earthquakes within the subducted Juan de Fuca plate, offshore megathrust earthquakes on Cascadia subduction zone and the shallow crustal earthquakes within the North American Plate.

For Seattle, a shallow crustal earthquake close to the city would be most damaging. The last major quake along the Seattle fault was in 900 AD, long before the city was established, though native people lived in the area. The earthquake triggered giant landslides along Lake Washington, causing entire blocks of forest to slide into the lake.

“There’s a kind of haunting precedence that tells us that we should pay attention to a large earthquake on this fault because it happened in the past,” said Allstadt, who also serves as duty seismologist for the Pacific Northwest Seismic Network. John Vidale of University of Washington and Art Frankel of the U.S. Geological Survey (USGS) are co-authors of the study, which was funded by the USGS.

While landslides triggered by earthquakes have caused damage and casualties worldwide, they have not often been the subject of extensive quantitative study or fully incorporated into seismic hazard assessments, say authors of this study that looks at just one scenario among potentially hundreds for a major earthquake in the Seattle area.

Dividing the area into a grid of 210-meter cells, they simulated ground motion for a magnitude 7 Seattle fault earthquake and then further subdivided into 5-meter cells, applying anticipated amplification of shaking due to the shallow soil layers. This refined framework yielded some surprises.

“One-third of the landslides triggered by our simulation were outside of the areas designated by the city as prone to landsliding,” said Allstadt. “A lot of people assume that all landslides occur in the same areas, but those triggered by rainfall or human behavior have a different triggering mechanism than landslides caused by earthquakes so we need dedicated studies.”

While soil saturation — whether the soil is dry or saturated with water – is the most important factor when analyzing the potential impact of landslides, the details of ground motion rank second. The amplification of ground shaking, directivity of seismic energy and geological features that may affect ground motion are very important to the outcome of ground failure, say authors.

The authors stress that this is just one randomized scenario study of many potential earthquake scenarios that could strike the city. While the results do not delineate the exact areas that will be affected in a future earthquake, they do illustrate the extent of landsliding to expect for a similar event.

The study suggests the southern half of the city and the coastal bluffs, many of which are developed, would be hardest hit. Depending upon the water saturation level of the soil at the time of the earthquake, several hundred to thousands of buildings could be affected citywide. For dry soil conditions, there are more than 1000 buildings that are within all hazard zones, 400 of those in the two highest hazard designation zones. The analysis suggests landslides could also affect some inland slopes, threatening key transit routes and impeding recovery efforts. For saturated soil conditions, it is an order of magnitude worse, with 8000 buildings within all hazard zones, 5000 of those within the two highest hazard zones. These numbers only reflect the number of buildings in high-risk areas, not the number of buildings that would necessarily suffer damage.

“The extra time we took to include the refined ground motion detail was worth it. It made a significant difference to our understanding of the potential damage to Seattle from seismically triggered landslides,” said Allstadt, who would like to use the new framework to run many more scenarios to prepare for future earthquakes in Seattle.

Note : The above story is based on materials provided by Seismological Society of America, via EurekAlert!, a service of AAAS.

Hadean Eon

The geological clock: a projection of Earth’s 4,5 Ga history on a clock Author: Woudloper Derivative work: Hardwigg Wikipedia

Table of Contents

The Hadean  is the first geologic eon of Earth and lies before the Archean. It began with the formation of the Earth about 4600 million years ago and ended as defined by the ICS 4,000 million years ago.

The name “Hadean” comes from Hades, the ancient Greek god of the underworld due to the “hellish” conditions on Earth at the time: the planet had just formed and was still very hot due to high volcanism, a partially molten surface and frequent collisions with other Solar System bodies.

The geologist Preston Cloud coined the term in 1972, originally to label the period before the earliest-known rocks on Earth. W. Brian Harland later coined an almost synonymous term: the “Priscoan period”. Other, older texts simply refer to the eon as the Pre-Archean.

Subdivisions

Since few geological traces of this eon remain on Earth there is no official subdivision. However, the Lunar geologic timescale embraces several major divisions relating to the Hadean and so these are sometimes used in a somewhat informal sense to refer to the same periods of time on Earth.

The Lunar divisions are:

  •     Pre-Nectarian, from the formation of the Moon’s crust up to about 3,920 million years ago
  •     Nectarian ranging up to about 3,850 million years ago, in a time when the Late Heavy Bombardment, according to that theory, was in a stage of decline.
There is a recently proposed alternative scale that includes the addition of the Chaotian and Prenephelean Eons preceding the Hadean, and divides the Hadean into three eras with two periods each. The Paleohadean era consists of the Hephaestean (4.5-4.4 Ga) and the Jacobian periods (4.4-4.3 Ga). The Mesohadean is divided into the Canadian (4.3-4.2 Ga) and the Procrustean periods (4.2-4.1 Ga). The Neohadean is divided into the Acastan (4.1-4.0 Ga) and the Promethean periods (4.0-3.9 Ga).

Hadean rocks

A sizeable quantity of water would have been in the material that formed the Earth. Water molecules would have escaped Earth’s gravity more easily when it was less massive during its formation. Hydrogen and helium are expected to continually escape (even to the present day) due to atmospheric escape.

Part of the ancient planet is theorized to have been disrupted by the impact that created the Moon, which should have caused melting of one or two large areas. Present composition does not match complete melting and it is hard to completely melt and mix huge rock masses. However, a fair fraction of material should have been vaporized by this impact, creating a rock vapor atmosphere around the young planet. The rock vapor would have condensed within two thousand years, leaving behind hot volatiles which probably resulted in a heavy CO2 atmosphere with hydrogen and water vapor. Liquid water oceans existed despite the surface temperature of 230 °C (446 °F) because of the atmospheric pressure of the heavy CO2 atmosphere. As cooling continued, subduction and dissolving in ocean water removed most CO2 from the atmosphere but levels oscillated wildly as new surface and mantle cycles appeared.

Study of zircons has found that liquid water must have existed as long ago as 4,400 million years ago, very soon after the formation of the Earth. This requires the presence of an atmosphere. The Cool Early Earth theory covers a range from about 4,400 to 4,000 million years ago.

A September 2008 study of zircons found that Australian Hadean rock holds minerals that point to the existence of plate tectonics as early as 4,000 million years ago. If this is true, the time when Earth finished its transition from having a hot, molten surface and atmosphere full of carbon dioxide, to being very much like it is today, can be roughly dated to about 4.0 billion years ago. The action of plate tectonics and the oceans traps vast amounts of carbon dioxide, thereby eliminating the greenhouse effect and leading to a much cooler surface temperature and the formation of solid rock, and possibly even life.

Note : The above story is based on materials provided by Wikipedia

Deepwater Mining in Norway

The islands along the Mid-Atlantic Ridge, such as Iceland and Jan Mayen, were created from red-hot lava escaping from the Earth's crust. The illustration shows a cross-section of the different layers of rock in the Earth's crust, both on land and the seabed. Areas along this fissure can be the source of valuable minerals. Credit: Geological Survey of Norway
The islands along the Mid-Atlantic Ridge, such as Iceland and Jan Mayen, were created from red-hot lava escaping from the Earth’s crust. The illustration shows a cross-section of the different layers of rock in the Earth’s crust, both on land and the seabed. Areas along this fissure can be the source of valuable minerals.
Credit: Geological Survey of Norway

The mid-ocean ridges where tectonic plates meet in the Atlantic and the Pacific Oceans are seething with volcanic activity. The most active areas are deep under water, several thousand metres down. Ocean water penetrates several kilometres down towards the centre of Earth where the crust is fractured. Geologists call this hydrothermal activity.

Liquid magma heats the water to about 400 °C before the water squirts back out again as an underwater geyser. The ocean water draws minerals and metals out of Earth’s crust and carries these back up to the seabed. Gold, silver, copper, cobalt, zinc, and lead are all deposited when the hot springs meet the cold ocean water.

This process formed the foundation for the land-based mines we have as well. The Norwegian ore deposits in Sulitjelma, Kongsberg and Røros were underwater 500 million years ago. But now, mines in Norway and elsewhere in the world are starting to run low on easily accessible ores. This coincides with a drastically increased demand for metals.

Several countries, including Norway, are now examining the possibility of mining the ocean floor.

Mapping the Mid-Atlantic Ridge

The Norwegian University of Science and Technology (NTNU), Statoil, and the mining company Nordic Mining are collaborating on a research project that will map marine mineral resources along the Mid-Atlantic Ridge. The parties signed a one-year collaboration agreement at the end of November 2012.

“Our primary goal is to map potential resources,” says Fredrik Søreide, an adjunct professor at NTNU’s Department of Marine Technology who is heading up the project. “We can then prioritize research and development as we move ahead.”

Researchers from the university’s Department of Geology and Mineral Resources Engineering and Applied Underwater Robotics Laboratory will also participate in this project.

The University of Bergen (UiB) has already gathered interesting samples from the Mid-Atlantic Ridge. The samples were extracted from the ridge in the area between Jan Mayen Island and the Fram Strait, off the east coast of Greenland. The researchers discovered an area of interest close to Jan Mayen in 2005. They named the area Soria Moria, after a castle in a Norwegian fairy tale.

Loki’s Castle

UiB’s scientists identified another large hydrothermal field with rich mineral deposits 300 km west of Bjørnøya in 2008. This field is located 2300 metres below the surface of the ocean. The field was named Loki’s Castle. It was hard to find, and was thus named after the Norse god Loki, who was a master of disguise. Loki’s Castle is the northernmost hydrothermal field that has been charted so far.

The researchers on the project will continue to map the ocean floor along the Mid-Atlantic Ridge for potential mineral deposits, using images from echo sounders and remotely operated submersible vessels.

“We still have many years of data collection ahead of us,” Søreide says. “But I do believe that Norway, with all of its offshore experience, is in a good position to develop this potential. It is likely that the mining industry will move offshore eventually, the same way that the petroleum industry did.

First minerals from the sea

The Canadian company Nautilus Minerals is the leader in marine mineral exploration. Nautilus Minerals has developed robotic technology for deep-sea mining in collaboration with the French company Technip. The company is planning to open the first deep-water mine in 2015. The Solwara 1 mine will be located 1600 metres below sea level. The company has found large deposits of copper and gold there. Solwara 1 is located in the Pacific Ocean, north of Australia, in Papua New Guinea.

Nautilus Minerals plans to continue searching for additional commercially viable deposits of copper, gold, zinc, and silver outside of Fiji, Tonga, the Solomon Islands, Vanuatu, and in the western part of the Pacific Ocean. Solwara 1 was supposed to start operations in 2013, but this was postponed. Local activists say that the environmental impact of the mine has not been fully investigated. The government of the independent island state of Papua New Guinea is currently negotiating with the mining company in terms of investments and profits.

Robots mining for gold

Nautilus Minerals will use submersible robots to work on the ocean floor and break apart loose ore. A pipeline will then transport the ore to a specialty vessel on the surface, which then will transport the ore to shore for refining.

“This is an extremely rich deposit of gold and copper,” says Terje Bjerkgård from Norway’s Geological Survey (NGU). He studies mineral resources and has participated in two research expeditions that included the area around Papua New Guinea.

“Underwater mining will first be commercialized in the Pacific,” he says. “The largest known deposit on the ocean floor is in Middle Valley in the northeast Pacific Ocean, off Canada. Other interesting deposits are north of New Zealand. Underwater mining will become more viable as land-based deposits become harder and more expensive to exploit. The challenges are tied to the distinct fauna around the hot springs.”

Black smokers

Rolf B. Pedersen, a professor at the University of Bergen, has been active in the exploration of the ocean floor along the Mid-Atlantic ridge. He is head of the Centre for Geobiology, which examines volcanic hydrothermal activity and the formation of the mineral resources. The Centre also conducts research on the biodiversity around underwater hot springs, including extremophile bacteria (bacteria that live in extreme environments). The Mid-Atlantic Ridge is populated by a unique fauna and flora. Scientists at the Centre discovered ten new species just in the area around Loki’s Castle. The mineral-rich water is the reason for the diversity.

Steaming chimneys called black smokers protrude from the volcanic areas at the bottom of the oceans. They can be several tens of metres tall, and grow as minerals are deposited when the hot water meets the cold ocean water at the outlet of the hydrothermal vents. Some of the metal sulphides precipitate right by the outlet, which contributes deposits that expand the structures, while the rest turn into a black smoke that the water pressure pumps into the water. The temperature of the water inside the “chimneys” can be as high as 400 °C.

The origin of life?

Hydrothermal chimneys were first observed in 1979, two years after hot springs were discovered close to the Galapagos Islands. The researchers used the submersible vessel Alvin to make the surprising discovery that volcanic areas are home to biological communities that derive their energy from chemical energy and not from sunlight. They also discovered a range of new and unknown species by the thermal vents.

The chemotrophic bacteria that live in and around the hydrothermal vents are able to use chemical energy from the mineral-rich water. The process provides all the energy this unique ecosystem requires to live. The discovery also created an understanding that the origin of life on Earth was not necessarily dependent on photosynthesis and sunlight.

“The environmental impact has not yet been examined,” says Pedersen. “The University of Bergen is a part of an international consortium that has applied for EU funding to examine the environmental impact. These special ecosystems mean it would only be appropriate to operate prospective mining operation in areas where the hydrothermal activity has ceased. However, industrial activities involve environmental consequences that have to be measured against the value of the activity.”

Obstacles beneath the surface

The problem is that inactive fields are very hard to discover with existing technology, which means that only active black smokers are currently being explored. This poses enough substantial enough challenges in and of itself, including environmental issues, technology, and great depths. Many countries are active in securing rights to underwater mineral resources, even though the start of large-scale mining efforts remains years away.

“Many countries, such as China, Russia, Japan, France and India, are positioning themselves strategically to secure resource areas in international waters,” says Søreide. “The politics of international oceans is full of intricate details, with a lot of the laws tied to the international laws of the sea.”

Interested governments have recently created rules for prospecting in international waters. Countries that have ratified the United Nations Convention on the Law of the Sea are bound by these rules. The US is among the countries that have not ratified the Convention.

Future Norwegian industry?

Norway is in special situation in regards to deep-water mining.

“Norway is unique in that these resources are within the Norwegian economic zone,” says Pedersen. “That means that underwater mining could be a future industry, when the technology is in place and if the environmental impacts are acceptable. The deposits have to be relatively big for the endeavour to be commercially profitable. There are big differences between the various estimates provided by researchers. We are trying to clarify the resource base, and need systematic studies regarding the deposits.”

This is exactly what the NTNU research project will contribute.

Note : The above story is based on materials provided by The Norwegian University of Science and Technology (NTNU), via AlphaGalileo. 

Mars once covered in giant supervolcanoes, scientists find

Colour-coded elevation image of Eden Patera, one of several sites on Mars that may be the footprints of ancient supervolcanoes. Photograph: Nasa/JPL/GSFC/Arizona State University/PA
Colour-coded elevation image of Eden Patera, one of several sites on Mars that may be the footprints of ancient supervolcanoes. Photograph: Nasa/JPL/GSFC/Arizona State University/PA

Ancient Mars was home to giant volcanoes capable of eruptions a thousand times more powerful than the one that shook Mount St Helens in 1980, scientists have said.

The finding raises fresh questions about conditions on Mars in its early years, a time when scientists believe the planet was much more Earth-like, with a thick atmosphere, warmer temperatures and water on its surface.

Major volcanic eruptions may well have triggered climate shifts that toggled Martian temperatures between cold spells when ash blocked out the sunlight and heat waves when greenhouse gases filled the skies, according to scientists.

Supervolcanoes may have made it more difficult for life to evolve on the planet’s surface, but underground steam vents and the release of water into the atmosphere also could have created niches for microbes to thrive, said geologist Joseph Michalski of the Planetary Science Institute in Tucson, Arizona.

The discovery of supervolcanoes on Mars comes from analysis of images from a quartet of Mars orbiters over the past 15 years.

These types of volcanoes, also known as “caldera” volcanoes, are ancient, collapsed structures rather than steep, cone-shaped or domed mountains like Olympus Mons on Mars, a so-called shield volcano that stands nearly three times taller than Mount Everest, the highest peak on Earth.

“We know a lot about the volcanic history of Mars over the last 3bn to 3.5bn years, but that still leaves about 1bn years before that over which we don’t really know anything about volcanism,” Michalski told Reuters.

Some scientists theorised that the oldest Martian volcanoes had eroded away, but the new findings suggest a different kind of volcano existed long ago.

“If early Mars saw a lot more explosive volcanism, then the features that are left from that don’t look like those shield volcanoes. That’s maybe why we didn’t see them,” Michalski said.

Scientists say supervolcanoes erupt with about 1,000 times the force of typical volcanoes like Mount St Helens in Washington state. The eruption of Mount St Helens in 1980 blasted the top off the mountain, killed 57 people and, according to the US Geological Survey, shot ash, steam, water and debris about 24,000 metres (80,000ft) into the air.

Evidence of past supervolcanoes on Earth has been erased by plate tectonics and other geologic activities.

Michalski was actually studying Martian impact craters, not looking for volcanoes.

“We made the discovery by accident,” he said. “As I went through [the images] of this one region, I found a number of them that were simply not impact craters,” he said.

“One was clearly a volcano. … It is quite possible there are many more of these,” Michalski added.

Because the emission of gases from volcanoes helps create a planet’s atmosphere, understanding the volcanic history of Mars is crucial to figuring out what the planet – the fourth from the Sun – was like in its early years.

Additional evidence may come from Nasa’s Mars Curiosity rover, which is heading toward a 3-mile-(5-km)-high mound of deposits called Mount Sharp.

The rover touched down inside a giant impact basin near the planet’s equator in August 2012 to assess if Mars ever had the chemistry and environment to support and preserve microbial life.

“There are thousands of layers of rocks in Mount Sharp and they contain a long record of geologic history,” Michalski said.

“There could be interlayered rocks that are ash beds, and we predict that and we hope that the rover can test it,” he said.

The research appears in the journal Nature.

Note: The above story is based on materials provided by Reuters in Houston

Crystals in Picabo’s rocks point to ‘recycled’ super-volcanic magma chambers

University of Oregon geologist Ilya Bindeman, left, and graduate student Dana Drew, working in Bindeman’s stable isotope laboratory say that the composition of zircon bits in igneous rocks in the Yellowstone hotspot track tell a new story on how super volcanoes recycle magma. Credit: University of Oregon

A thorough examination of tiny crystals of zircon, a mineral found in rhyolites, an igneous rock, from the Snake River Plain has solidified evidence for a new way of looking at the life cycle of super-volcanic eruptions in the long track of the Yellowstone hotspot, say University of Oregon scientists.

The pattern emerging from new and previous research completed in the last five years under a National Science Foundation career award, said UO geologist Ilya N. Bindeman, is that another super-eruption from the still-alive Yellowstone volcanic field is less likely for the next few million years than previously thought. The last eruption 640,000 years ago created the Yellowstone Caldera and the Lava Creek Tuff in what is now Yellowstone National Park.

The Yellowstone hotspot creates a conveyor belt style of volcanism because of the southwest migration of the North American plate at 2-4 centimeters (about .8 to 1.6 inches) annually over the last 16 million years of volcanism. Due to the movement of the North American plate, the plume interaction with the crust leaves footprints in the form of caldera clusters, in what is now the Snake River Plain, Bindeman said.

The Picabo volcanic field of southern Idaho, described in a new paper by a six-member team, was active between 10.4 and 6.6 million years ago and experienced at least three, and maybe as many as six, violent caldera-forming eruptions. The field has been difficult to assess, said lead author Dana Drew, a UO graduate student, because the calderas have been buried by as much as two kilometers of basalt since its eruption cycle died.

The work at Picabo is detailed in a paper online ahead of publication in the journal Earth and Planetary Science Letters.

The team theorized that basalt from the mantle plume, rocks from Earth’s crust and previously erupted volcanoes are melted together to form the rhyolites erupted in the Snake River Plain. Before each eruption, rhyolite magma is stored in dispersed pockets throughout the upper crust, which are later mixed together, according to geochemical evidence. “We think that this batch-assembly process is an important part of caldera-forming eruptions, and generating rhyolites in general,” Drew said.

In reaching their conclusions, Drew and colleagues analyzed radiogenic and stable isotopic data—specifically oxygen and hafnium—in zircons detected in rhyolites found at the margins of the Picabo field and from a deep borehole. That data, in combination with whole rock geochemistry and zircon uranium-lead geochronology helped provide a framework to understand the region’s ancient volcanic past.

Previous research on the related Heise volcanic field east of Picabo yielded similar results. “There is a growing database of the geochemistry of rhyolites in the Yellowstone hotspot track,” Drew said. “Adding Picabo provides a missing link in the database.

Drew and colleagues, through their oxygen isotope analyses, identified a wide diversity of oxygen ratios occurring in erupted zircons near the end of the Picabo volcanic cycle. Such oxygen ratios are referred to as delta-O-18 signatures based on oxygen 18 levels relative to seawater. (Oxygen 18 contains eight protons and 10 neutrons; Oxygen 16, with eight protons and eight neutrons, is the most commonly found form of oxygen in nature)

The approach provided a glimpse into the connection of surface and subsurface processes at a caldera cluster. The interaction of erupted rhyolite with groundwater and surface water causes hydrothermal alteration and the change in oxygen isotopes, thereby providing a fingerprinting tool for the level of hydrothermal alteration, Drew said.

“Through the eruptive sequence, we begin to generate lower delta-O-18 signatures of the magmas and, with that, we also see a more diverse signature,” Drew said. “By the time of the final eruption there is up to five per mil diversity in the signature recorded in the zircons.” The team attributes these signatures to the mixing of diverse magma batches dispersed in the upper crust, which were formed by melting variably hydrothermally altered rocks—thus diverse delta-O-18—after repeated formation of calderas and regional extension or stretching of the crust.

When the pockets of melt are rapidly assembled, the process could be the trigger for caldera forming eruptions, Bindeman said. “That leads to a homogenized magma, but in a way that preserves these zircons of different signatures from the individual pockets of melt,” he said. This research, he added, highlights the importance of using new micro-analytical isotopic techniques to relate geochemistry at the crystal-scale to processes occurring at the crustal-wide scale in generating and predicting large-volume rhyolitic eruptions.

“This important research by Dr. Bindeman and his team demonstrates the enormous impact an NSF CAREER award can have,” said Kimberly Andrews Espy, vice president for research and innovation and dean of the graduate school at the University of Oregon. “The five-year project is providing new insights into the eruption cycles of the Yellowstone hotspot and helping scientists to better predict future volcanic activity.”

Note: The above story is based on materials provided by University of Oregon

The Complicated Birth of a Volcano

A full chain bag dredge of samples obtained from the Marie Byrd Seamounts is emptied on board of POLARSTERN. (Credit: F. Hauff, GEOMAR)

They are difficult to reach, have hardly been studied scientifically, and their existence does not fit into current geological models: the Marie Byrd Seamounts off the coast of Antarctica present many riddles to volcanologists.

In the international journal “Gondwana Research,” scientists from GEOMAR Helmholtz Centre for Ocean Research Kiel in cooperation with colleagues from the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research just published possible explanations for the origin of these former volcanoes and thus contributed to the decryption of complex processes in the Earth’s interior.

Snow storms, ice and glaciers — these are the usual images we associate with the Antarctic. But at the same time it is also a region of fire: the Antarctic continent and surrounding waters are dotted with volcanoes — some of them still active and others extinct for quite some time. The Marie Byrd Seamounts in the Amundsen Sea are in the latter group.

Their summit plateaus are today at depths of 2400-1600 meters. Because they are very difficult to reach with conventional research vessels, they have hardly been explored, even though the Marie Byrd Seamounts are fascinating formations.

They do not fit any of the usual models for the formation of volcanoes. Now geologists from GEOMAR Helmholtz Centre for Ocean Research Kiel were able to find a possible explanation for the existence of these seamounts on the basis of rare specimens. The study is published in the international journal “Gondwana Research.”

Classic volcanologists differentiate between two types of fire mountains. One type is generated where tectonic plates meet, so the earth’s crust is already cracked to begin with. The other type is formed within the earth’s plates. “The latter are called intraplate volcanoes. They are often found above a so-called mantle plume.

Hot material rises from the deep mantle, collects under the earth’s crust, makes its way to the surface and forms a volcano,” said Dr. Reinhard Werner, one of the authors of the current paper. One example are the Hawaiian Islands. But neither of the above models fits the Marie Byrd Seamounts. “There are no plate boundaries in the vicinity and no plumes underground,” says graduate geologist Andrea Kipf from GEOMAR, first author of the study.

To clarify the origin of the Marie Byrd Seamounts, in 2006 the Kiel scientists participated in an expedition of the research vessel POLARSTEN in the Amundsen Sea. They salvaged rock samples from the seamounts and subjected these to thorough geological, volcanological and geochemical investigations after returning to the home labs. “Interestingly enough, we found chemical signatures that are typical of plume volcanoes. And they are very similar to volcanoes in New Zealand and the Antarctic continent,” says geochemist Dr. Folkmar Hauff, second author of the paper.

Based on this finding, the researchers sought an explanation. They found it in the history of tectonic plates in the southern hemisphere. Around 100 million years ago, remains of the former supercontinent Gondwana were located in the area of present Antarctica. A mantle plume melted through this continental plate and cracked it open.

Two new continents were born: the Antarctic and “Zealandia,” with the islands of New Zealand still in evidence today. When the young continents drifted in different directions away from the mantle plume, large quantities of hot plume material were attached to their undersides. These formed reservoirs for future volcanic eruptions on the two continents. “This process explains why we find signatures of plume material at volcanoes that are not on top of plumes,” says Dr. Hauff.

But that still does not explain the Marie Byrd Seamounts because they are not located on the Antarctic continent, but on the adjacent oceanic crust instead. “Continental tectonic plates are thicker than the oceanic ones. This ensures, among other things, differences in temperature in the underground,” says volcanologist Dr. Werner. And just as air masses of different temperatures create winds, the temperature differences under the earth’s crust generate flows and movements as well. Thus the plume material, that once lay beneath the continent, was able to shift under the oceanic plate.

With disruptions due to other tectonic processes, there were cracks and crevices which allowed the hot material to rise, turn into magma and then- about 60 million years ago — allowed the Marie Byrd Seamounts to grow. “This created islands that are comparable to the Canary Islands today,” explains Andrea Kipf. “Some day the volcanoes became extinct again, wind and weather eroded the cone down to sea level, and other geological processes further eroded the seamounts. Finally, the summit plateaus arrived at the level that we know today,” the PhD student describes the last step of the development.

Based on the previously little investigated Marie Byrd Seamounts, the researchers were able to show another example of how diverse and complex the processes are, that can cause volcanism. “We are still far from understanding all of these processes. But with the current study, we can contribute a small piece to the overall picture,” says Dr. Werner.

Note: The above story is based on materials provided by Helmholtz Centre for Ocean Research Kiel (GEOMAR).

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