New Study Maps Rate of New Orleans Sinking

May 17, 2016

New Study Maps Rate of-GeologyPage — Subsidence in Jefferson Parish, Louisiana, from June 2009 to July 2012, as seen by NASA’s UAVSAR instrument. The measured displacements are a combination of movement of the ground and of individual structures. The inset at lower right shows the parish location within Greater New Orleans. Credit: NASA/JPL-Caltech, Esri

New Orleans and surrounding areas continue to sink at highly variable rates due to a combination of natural geologic and human-induced processes, finds a new NASA/university study using NASA airborne radar.

The observed rates of sinking, otherwise known as subsidence, were generally consistent with, but somewhat higher than, previous studies conducted using different radar data.

The research was the most spatially-extensive, high-resolution study to date of regional subsidence in and around New Orleans, measuring its effects and examining its causes. Scientists at NASA’s Jet Propulsion Laboratory, Pasadena, California; UCLA; and the Center for GeoInformatics at Louisiana State University, Baton Rouge, collaborated on the study, which covered the period from June 2009 to July 2012.

The highest rates of sinking were observed upriver along the Mississippi River around major industrial areas in Norco, and in Michoud, with up to 2 inches (50 millimeters) a year of sinking. The team also observed notable subsidence in New Orleans’ Upper and Lower 9th Ward, and in Metairie, where the measured ground movement could be related to water levels in the Mississippi. At the Bonnet Carré Spillway east of Norco—New Orleans’ last line of protection against springtime river floods overtopping the levees—research showed up to 1.6 inches (40 millimeters) a year of sinking behind the structure and up to 1.6 inches (40 millimeters) a year at nearby industrial facilities.

While the study cites many contributing factors for the regional subsidence, the primary contributors were found to be groundwater pumping and dewatering (surface water pumping to lower the water table, which prevents standing water and soggy ground).

JPL scientist and lead author Cathleen Jones said study results will be used to improve models of subsidence for the Mississippi River Delta that decision makers use to inform planning.

“Agencies can use these data to more effectively implement actions to remediate and reverse the effects of subsidence, improving the long-term coastal resiliency and sustainability of New Orleans,” Jones said. “The more recent land elevation change rates from this study will be used to inform flood modeling and response strategies, improving public safety.”

To fully and accurately measure and predict future subsidence in and around New Orleans, it’s necessary to better understand the various natural and human-produced processes contributing to the sinking. Those include withdrawal of water, oil and gas; compaction of shallow sediments; faulting; sinking of Earth’s crust from the weight of deposited sediments; and ongoing vertical movement of land covered by glaciers during the last ice age. Jones said the comprehensive subsidence maps produced by this study, with their improved spatial resolution, help scientists differentiate these processes.

The maps were created using data from NASA’s Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR), which uses a technique known as interferometric synthetic aperture radar (InSAR). InSAR compares radar images of Earth’s surface over time to map surface deformation with centimeter-scale precision. It measures total surface elevation changes from all sources—human and natural, deep seated and shallow. Its data must be carefully interpreted to disentangle these phenomena, which operate at different time and space scales. UAVSAR’s spatial resolution makes it ideal for measuring subsidence in New Orleans, where human-produced subsidence can be large and is often localized.

Jones said another key advantage of this study is that UAVSAR enabled better resolution of small-scale features than previous studies. “We were able to identify single structures or clusters of structures subsiding or deforming relative to the surrounding area,” she said.

In addition to the UAVSAR data, researchers from the Center for GeoInformatics (C4G) at Louisiana State University provided up-to-date GPS positioning information for industrial and urban locations within southeast Louisiana. This information helped establish the rate of ground movement at these specific points. C4G maintains the most comprehensive network of GPS reference stations in the state. The Louisiana network consists of more than 50 Continuously Operating Reference Stations, or CORS sites, which acquire the horizontal and vertical coordinates at each station every second of every day. The CORS sites are part of the National Geodetic Survey network.

CORS data pin InSAR data down to specific, local points on Earth. The LSU research team derived the positional time series using precise point positioning software developed by JPL.

“We define all the parameters to reduce the ambiguities. This enables us to distill a location down to millimeter-level precision,” said Joshua Kent, Geographic Information System manager at C4G. “A wide range of people rely on the CORS data, from geoscientists to surveyors, engineers and farmers.”

The study is published in the Journal of Geophysical Research: Solid Earth.

NASA uses the vantage point of space to increase our understanding of our home planet, improve lives and safeguard our future. NASA develops new ways to observe and study Earth’s interconnected natural systems with long-term data records. The agency freely shares this unique knowledge and works with institutions around the world to gain new insights into how our planet is changing.

UAVSAR was developed and is managed by JPL and flies on a C-20A research aircraft based at NASA’s Armstrong Flight Research Center facility in Palmdale, California. Developed to test new technologies and study Earth surface dynamics, UAVSAR data are informing the design and planning for a future spaceborne radar mission, the NASA-ISRO Synthetic Aperture Radar (NISAR), which is planned to image Earth’s surface at least once every 12 days.

Subsidence on the Gulf Coast: Old Problem, New Challenges

Around the world, the loss of delta lands due to subsidence and associated increases in flood risk are major issues facing coastal communities, especially in the face of ongoing and possibly accelerating global sea level rise. The Mississippi River delta is losing its natural coastal barriers—the delta wetlands and barrier islands—increasing flood risk across the area. In response, the region has increased investment in infrastructure and restoration activities to protect human populations and areas of high economic value.

The landscape of Southeast Louisiana was built upon a coastal delta created by the Mississippi River during the past 8,000 years as sea level rise due to glacial melting in the last ice age slowed. Before humans intervened, natural subsidence was offset by a combination of sediments deposited during Mississippi River floods and organic soil produced from the decay of wetland vegetation. Construction of flood control levees to protect the Gulf Coast economy and local populations interrupted the sediment supply, leading to a net increase in land subsidence.

In Greater New Orleans, local geology plays a major role in flooding and subsidence. The city lies along the current path of the Mississippi River and is built on modern and past natural levees and buried or artificially drained swamps and marshes. It is located in an area that has received sediments from multiple lobes of the Mississippi River delta over time.

For more information on UAVSAR, visit uavsar.jpl.nasa.gov/
For more information on NISAR, visit nisar.jpl.nasa.gov/

Note: The above post is reprinted from materials provided by NASA.

UC geologists identify sources of methane, greenhouse gas, in Ohio, Colorado and Texas

May 17, 2016

UC geologists identify sources of methane-GeologyPage — A drilling rig in Carroll County, Ohio. Credit: Amy Townsend-Small, University of Cincinnati

Researchers from the University of Cincinnati recently studied the sources of methane at three sites across the nation in order to better understand this greenhouse gas, which is much more potent at trapping heat in the atmosphere than is carbon dioxide.

The UC team, led by Amy Townsend-Small, assistant professor of geology, identified sources for methane in Carroll County, Ohio; Denver, Colorado; and Dallas/Fort Worth, Texas, by means of an analysis technique that consists of measuring carbon and hydrogen stable isotopes (isotopic composition). This approach provides a signature indicating whether methane is coming from, say, natural gas extraction (fracking), organic/biologic decay, or the natural digestive processes of cattle.

Said Townsend-Small, “This is an analysis technique that provides answers regarding key questions as to specific sources for methane emissions. With isotopic composition analysis, it’s possible to tell whether the source is fracking or biogenic processes (like bacterial decomposition in landfills or algae-filled water). It’s a laborious technique to implement, but its use makes it possible to trace and attribute the source of methane production.”

In findings to be presented at the May 18-21 regional American Chemical Society Conference held in Covington, Ky., Townsend-Small will present research results achieved with a team consisting of Claire Botner, recent UC graduate student; Paul Feezel of Carroll County Concerned Citizens; Don Blake, professor of chemistry, University of California-Irvine, and Josette Marrero, former UC-Irvine doctoral student.

As part of the ACS program, she will report on a 2012-15 study examining methane levels and origins of methane in groundwater in the Utica Shale region of eastern Ohio:

MONITORING GROUNDWATER SUPPLIES NEAR OHIO FRACKING SITES

The UC Groundwater Research of Ohio program first launched in 2012 in Carroll County, Ohio, when there were only three fracking (hydraulic fracturing) wells in the county. The goal of the research was to establish a baseline for methane levels and origins of methane in private wells and springs before, during and after the onset of fracking. By the time the study was complete, there were 354 fracking wells in the county.

Results from this study, where 23 wells were tested three to four times each year and a total of 191 samples examined, found that methane levels in these groundwater wells came from decay of organic matter (decomposition of plants) biological processes occurring in subsurface coal formations. In less than a handful of cases, the natural methane levels were relatively high (above 10 milligrams per liter). However, most of the wells carried low levels of methane.

The water wells varied in their distance from active natural gas wells, from 1 kilometer to more than 10 kilometers.

And update and in-process results of this study were released via a 2014 university news release subsequently carried by news media at that time.

MONITORING FRACKING IN COLORADO AND TEXAS

In the Denver Basin, which encompasses the city of Denver and the surrounding region, Townsend-Small and her team examined about 200 methane samples in 2014, collecting airborne measurements via aircraft as well as measuring methane levels on the ground, site by site.

Collection efforts focused on both atmospheric data and ground-level, site-specific samples in order to help ensure accuracy via cross checking of results.

In the Denver region, the isotopic composition signatures of the samples collected demonstrated that up to 50 percent of methane emissions in the region were from agricultural practices (cattle) and/or landfill sources, with the other half (about 50 percent) coming from fracking for natural gas.

Similar testing in the Barnett Shale region of Dallas/Fort Worth, involving the collection and analysis of 120 samples in 2013, found that 64 percent of the methane emissions came from fracking while 36 percent came from landfills and cattle.

Note: The above post is reprinted from materials provided by University of Cincinnati.

Ecological method for cleaning oil from lakes

May 17, 2016

Ecological method for-GeologyPage — This is Danil Vorobiev, doctor of biological sciences and director of biological institute near the lake. Credit: TSU

The oil cleansing method was developed by TSU researchers and it is optimal for lake ecosystems. The experiment proved that the content of oil in water reduced in 35-40 times. Date of the research was published in journals Water Practice & Technology.

“The technology is based on flotation method,” said Danil Vorobiev one of the authors of this development, doctor of biological sciences and director of Biological institute. — In place of oil accumulation we perform pneumatic and mechanical action and as a result oil sticks to the section of the two phases — liquid and air — and rises to the surface.

The technology, developed by TSU, best suited for lakes with thick sediments: stony, clay or sandy bottom. This method allows cleaning both sediments and water and there are no any restrictions on the depth of the pond.

This method does not require using any chemicals. Also this method can be used in winter when vegetative processes in a lake “freeze” and interference with the underwater world is minimal.

– In the spring and summer fish and aquatic organisms actively reproduce, therefore it is better to conduct any cleaning work during the cold time of the year, — the TSU scientist says. — It is necessary to take into account the fact that many Russian contaminated lakes are in remote places, we can get there and take out the oil from the bottom only by winter road. For such reservoirs the under-ice cleaning method is the only option.

In cold weather, we move the perforated hose down to the bottom in order to direct the pressurized stream of air to accumulations of oil. As a result, oil rises to the surface and goes via the guide channels laid on the surface to an oil collector. A mobile hangar is installed above the oil collector where heat guns create a favourable temperature for pumping oil. This allows working on cleaning water from oil in any weather, even at -50°C.

In addition, the TSU Institute of Biology received a patent for this invention.

Reference:
D. S. Vorobiev, Y. A. Frank, Y. A. Noskov, O. E. Merzlyakov, S. P. Kulizhskiy. Novel technological solution for oil decontamination of bottom sediments. Water Practice and Technology, 2016; 11 (1): 139 DOI: 10.2166/wpt.2016.017

Note: The above post is reprinted from materials provided by National Research Tomsk State University.

Can fluids from fracking escape into groundwater

May 17, 2016

$Can fluids from fracking-GeologyPage$

A new study looks at how fluids related to hydraulic fracturing or “fracking” can escape into aquifers via nearby leaky abandoned wells.

This could lead to upward leakage of contaminants; however, flows into leaky wells do not conclusively demonstrate that contaminants from a fractured shale reservoir can migrate into the overlying aquifer because hydraulic characteristics of the well may limit migration. Moreover, production of the horizontal well after hydraulic fracturing can play a significant role in reducing or inhibiting potential upward leakage.

“This research indicates certain historical oil and gas activities may affect hydraulic fracturing, and these historical data need to be studied more closely,” said Dr. Joshua Brownlow, lead author of the Groundwater study. “Hopefully, this study will help water managers and industry use our resources more effectively.”

Reference:

Joshua W. Brownlow, Scott C. James, Joe C. Yelderman Jr., Influence of Hydraulic Fracturing on Overlying Aquifers in the Presence of Leaky Abandoned Wells. DOI: 10.1111/gwat.12431
Influence of Hydraulic Fracturing on Overlying Aquifers in the Presence of Leaky Abandoned Wells. NRU-16 May-GWAT-Fracking

Note: The above post is reprinted from materials provided by Wiley.

Devils Tower

May 16, 2016

Devils Tower was the first declared United States National Monument, established on September 24, 1906, by President Theodore Roosevelt. The Monument’s boundary encloses an area of 1,347 acres (545 ha).

In recent years, about 1% of the Monument’s 400,000 annual visitors climbed Devils Tower, mostly using traditional climbing techniques.

Name

Tribes including the Arapaho, Crow, Cheyenne, Kiowa, Lakota, and Shoshone had cultural and geographic ties to the monolith before non-Native Americans reached Wyoming. Their names for the monolith include: Aloft on a Rock (Kiowa), Bear’s House (Cheyenne, Crow), Bear’s Lair (Cheyenne, Crow), Daxpitcheeaasáao, “Home of bears” (Crow), Bear’s Lodge (Cheyenne, Lakota), Bear’s Lodge Butte (Lakota), Bear’s Tipi (Arapaho, Cheyenne), Tree Rock (Kiowa), and Grizzly Bear Lodge (Lakota).

The name Devil’s Tower originated in 1875 during an expedition led by Col. Richard Irving Dodge when his interpreter misinterpreted the name to mean Bad God’s Tower, which then became Devil’s Tower. All information signs in that area use the name “Devils Tower”, following a geographic naming standard whereby the apostrophe is eliminated.

In 2005, a proposal to recognize several American Indian ties through the additional designation of the monolith as Bear Lodge National Historic Landmark met with opposition from the United States Representative Barbara Cubin, arguing that a “name change will harm the tourist trade and bring economic hardship to area communities”.

In November 2014, Arvol Looking Horse, an American Indian spiritual leader, again proposed renaming the geographical feature “Bear Lodge”, and submitted the request to the Board of Geographic Names. A second proposal was submitted to request that the US acknowledge the “offensive” mistake and to rename the monument and sacred site Bear Lodge National Historic Landmark. The formal public comment period will end in fall 2015. Local state senator Ogden Driskill opposed the change.

Geological history

The landscape surrounding Devils Tower is composed mostly of sedimentary rocks. The oldest rocks visible in Devils Tower National Monument were laid down in a shallow sea during the Triassic period, 225 to 195 million years ago. This dark red sandstone and maroon siltstone, interbedded with shale, can be seen along the Belle Fourche River. Oxidation of iron minerals causes the redness of the rocks. This rock layer is known as the Spearfish Formation.

Above the Spearfish formation is a thin band of white gypsum, called the Gypsum Springs Formation. This layer of gypsum was deposited during the Jurassic period, 195 to 136 million years ago.

Created as sea levels and climates repeatedly changed, gray-green shales (deposited in low-oxygen environments such as marshes) were interbedded with fine-grained sandstones, limestones, and sometimes thin beds of red mudstone. This composition, called the Stockade Beaver member, is part of the Sundance Formation. The Hulett Sandstone member, also part of the Sundance formation, is composed of yellow fine-grained sandstone. Resistant to weathering, it forms the nearly vertical cliffs which encircle the Tower itself.

During the Paleocene Epoch, 56 to 66 million years ago, the Rocky Mountains and the Black Hills were uplifted. Magma rose through the crust, intruding into the existing sedimentary rock layers.

Theories of formation

Geologists Carpenter and Russell studied Devils Tower in the late 19th century and came to the conclusion that it was formed by an igneous intrusion. Modern geologists agree that it was formed by the intrusion of igneous material, but not on exactly how that process took place. Several believe the molten rock comprising the Tower might not have surfaced; others are convinced the tower is all that remains of what once was a large explosive volcano.

In 1907, scientists Darton and O’Harra decided that Devils Tower must be an eroded remnant of a laccolith. A laccolith is a large mass of igneous rock which is intruded through sedimentary rock beds without reaching the surface, but makes a rounded bulge in the sedimentary layers above. This theory was quite popular in the early 20th century since numerous studies had earlier been done on laccoliths in the Southwest.

Other theories have suggested that Devils Tower is a volcanic plug or that it is the neck of an extinct volcano. Presumably, if Devils Tower was a volcanic plug, any volcanics created by it — volcanic ash, lava flows, volcanic debris — would have been eroded away long ago. Some pyroclastic material of the same age as Devils Tower has been identified elsewhere in Wyoming.

The igneous material that forms the Tower is a phonolite porphyry intruded about 40.5 million years ago, a light to dark-gray or greenish-gray igneous rock with conspicuous crystals of white feldspar. As the magma cooled, hexagonal (and sometimes 4-, 5-, and 7-sided) columns formed. As the rock continued to cool, the vertical columns shrank in cross-section (horizontally) and cracks began to occur at 120 degree angles, generally forming compact 6-sided columns. The nearby Missouri Buttes, 3.5 miles (5.6 km) to the northwest of Devils Tower, are also composed of columnar phonolite of the same age. Superficially similar, but with typically 2 feet (0.61 m) diameter columns, Devils Postpile National Monument and Giant’s Causeway are columnar basalt.

Devils Tower did not visibly protrude out of the landscape until the overlying sedimentary rocks eroded away. As the elements wore down the softer sandstones and shales, the more resistant igneous rock making up the tower survived the erosional forces. As a result, the gray columns of Devils Tower began to appear as an isolated mass above the landscape.

As rain and snow continue to erode the sedimentary rocks surrounding the Tower’s base, more of Devils Tower will be exposed. Nonetheless, the exposed portions of the Tower still experience certain amounts of erosion. Cracks along the columns are subject to water and ice erosion. Erosion due to the expansion of ice along cracks and fractures within rock formations is common in colder climates — a prime example being the featured formations at Bryce Canyon National Park. Portions, or even entire columns, of rock at Devils Tower are continually breaking off and falling. Piles of broken columns, boulders, small rocks, and stones — or scree — lie at the base of the tower, indicating that it was once wider than it is today.

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Devils Tower

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Note: The above post is reprinted from materials provided by Wikipedia.

Study pinpoints timing of oxygen’s first appearance in Earth’s atmosphere

May 16, 2016

Study pinpoints timing of oxygen-GeologyPage — MIT scientists say that the Great Oxygenation Event (GOE), a period that scientists believe marked the beginning of oxygen’s permanent presence in the atmosphere, started as early as 2.33 billion years ago.

Today, 21 percent of the air we breathe is made up of molecular oxygen. But this gas was not always in such ample, life-sustaining supply, and in fact was largely absent from the atmosphere for the first 2 billion years of Earth’s history. When, then, did oxygen first accumulate in the atmosphere?

MIT scientists now have an answer. In a paper appearing today in Science Advances, the team reports that the Earth’s atmosphere experienced the first significant, irreversible influx of oxygen as early as 2.33 billion years ago. This period marks the start of the Great Oxygenation Event, which was followed by further increases later in Earth’s history.

The scientists have also determined that this initial rise in atmospheric oxygen, although small, took place within just 1 to 10 million years and set off a cascade of events that would ultimately lead to the advent of multicellular life.

“It’s the start of a very long interval that culminated in complex life,” says Roger Summons, senior author of the paper and professor in the Department of Earth, Atmospheric, and Planetary Sciences (EAPS) at MIT. “It took another roughly 1.7 billion years for animals similar to those we have today to evolve. But the presence of molecular oxygen in the ocean and the atmosphere means that organisms that respire oxygen could thrive.”

Summons’ MIT co-authors include lead author and postdoc Genming Luo, as well as EAPS Associate Professor Shuhei Ono and graduate student David Wang. Professors Nicolas Beukes from the University of Johannesburg, in South Africa, and Shucheng Xie from the China University of Geosciences are the other co-authors.

Whiffs in the air

For the most part, scientists agree that oxygen, though lacking in the atmosphere, was likely brewing in the oceans as a byproduct of cyanobacterial photosynthesis as early as 3 billion years ago. However, as Summons puts it, oxygen in the ancient ocean “would have instantly been sucked up” by hungry microbes, ferrous iron, and other sinks, keeping it from escaping into the atmosphere.

“There may have been earlier, and temporary, ‘whiffs’ of oxygen in the atmosphere, but their abundances and durations are not currently measurable,” Summons says.

That changed with the Great Oxygenation Event (GOE), a period that scientists believe marked the beginning of oxygen’s permanent presence in the atmosphere. Previous estimates have placed the start of the GOE at around 2.3 billion years ago, though with uncertainties of tens to hundreds of millions of years.

“The dating of this event has been rather imprecise until now,” Summons says.

A transition, pinned

To get a more precise timing for the GOE, Genming Luo first analyzed rocks from around this period. Luo was looking for a particular sulfur isotope pattern called mass-independent fraction of sulfur isotopes (S-MIF) in order to determine when oxygen first appeared in the Earth’s atmosphere.

To get a more precise timing for the GOE, Luo first analyzed rocks from around this period, looking for a particular sulfur isotope pattern. When volcanoes erupt, they emit sulfur gases, which, when exposed to the sun’s ultraviolet radiation, can fractionate chemically and isotopically. The pattern of isotopes generated in this process depends on whether or not oxygen was present above a certain threshold.

Luo looked to pinpoint a major transition in a particular sulfur isotope pattern called mass-independent fraction of sulfur isotopes (S-MIF), in order to determine when oxygen first appeared in the Earth’s atmosphere. To do this, he first looked through sediment cores collected by Ono on a previous expedition to South Africa.

“Genming is a very tenacious and thorough guy,” Summons says. “He found rocks from deep in the core had S-MIF, and rocks shallow in the core had no S-MIF, but he didn’t have anything in between. So he went back to South Africa.”

There, he was able to sample from the rest of the sediment core and two others nearby, and determined that the S-MIF transition—marking the permanent passing of the oxygen threshold—occurred 2.33 billion years ago, plus or minus 7 million years, a much smaller uncertainty compared with previous estimates.

Getting a “decent hold”

The team also discovered a large fractionation of the isotope sulfur-34, indicating a spike in marine sulfate levels around this same time. Such sulfate would have been produced from the reaction between atmospheric oxygen with sulfide minerals in rocks on land, and sulfur dioxide from volcanoes. This sulfate was then used by ocean-dwelling, sulfate-respiring bacteria to generate a particular pattern of sulfur-34 in subsequent sediment layers that were dated between 1 and 10 million years after the S-MIF transition.

The results suggest that the initial buildup of oxygen in the atmosphere was relatively rapid. Since its first appearance 2.33 billion years ago, oxygen accumulated in high enough concentrations to have a weathering effect on rocks just 10 million years later. This weathering process, however, would have leached more sulfate and certain metals into waterways and ultimately, the oceans. Summons points out that it would be quite some time before the Earth system would reach another stable state, by the burial of organic carbon, and exceed the higher oxygen thresholds needed to encourage further biological evolution.

“Complex life couldn’t really get a decent hold on the planet until oxygen was prevalent in the deep ocean,” Summons says. “And that took a long, long time. But this is the first step in a cascade of processes.”

Timothy Lyons, professor of biogeochemistry at the University of California, Riverside, says the group’s timeline for oxygen’s rise “is a major contribution toward a refined understanding of the co-evolution of Earth’s early life and environments.”

“There are hints from past research of early transient accumulation of oxygen in the atmosphere and surface oceans before the loss of S-MIF, but the irreversible loss of this signal from the geologic record is now taken as the smoking gun for what we call the Great Oxidation Event—when appreciable levels of oxygen became a permanent feature in our atmosphere,” says Lyons, who did not contribute to the research. “The authors have done the community a great service by refining the timing of this event.”

Now that the team has constrained the timing of the GOE, Summons hopes others will apply the new dates to determine a cause, or mechanism, for the event. One hypothesis that the team hopes to explore is the connection between oxygen’s sudden and rapid appearance, and Snowball Earth, the period in which Earth’s continents and oceans were largely ice-covered. Now, thanks to the improved precision in geochronology, which Summons largely credits to EAPS Professor Samuel Bowring, scientists can start to nail down the mechanisms behind major events in Earth’s history, with more precise dates.

“It’s Sam’s insistence about this whole issue about ‘no dates, no rates’ that I think encourages people to focus on getting better data on the timing and duration of geological events,” Summons says.

“Because the other big question is, why do we have 21 percent oxygen in the Earth’s atmosphere that’s stable? That’s remarkable. And we need to understand that.”

Reference:
G. Luo et al. Rapid oxygenation of Earths atmosphere 2.33 billion years ago, Science Advances (2016). DOI: 10.1126/sciadv.1600134

Note: The above post is reprinted from materials provided by Massachusetts Institute of Technology.

The Twelve Apostles, Australia

May 15, 2016

header-GeologyPage

The Twelve Apostles is a collection of limestone stacks off the shore of the Port Campbell National Park, by the Great Ocean Road in Victoria, Australia. Their proximity to one another has made the site a popular tourist attraction. Currently there are eight apostles left, the ninth one of the stacks collapsed dramatically in July 2005. The name remains significant and spectacular especially in the Australian tourism industry.

Formation and history

The apostles were formed by erosion: the harsh and extreme weather conditions from the Southern Ocean gradually eroded the soft limestone to form caves in the cliffs, which then became arches, which in turn collapsed; leaving rock stacks up to 50 metres high. Now because of this erosion there are fewer than ten remaining. The site was known as the Sow and Piglets until 1922 (Muttonbird Island, near Loch Ard Gorge, was the Sow, and the smaller rock stacks were the Piglets); after which it was renamed to The Apostles for tourism purposes. The formation eventually became known as the Twelve Apostles, despite only ever having nine stacks.

In 2002, the Port Campbell Professional Fishermens Association unsuccessfully attempted to block the creation of a proposed marine national park at the Twelve Apostles location, but were satisfied with the later Victorian Government decision not to allow seismic exploration at the same site by Benaris Energy; believing it would harm marine life.

The stacks are susceptible to further erosion from the waves. On 3 July 2005, a 50-metre-tall (160 ft) stack collapsed, leaving eight remaining (compare the two pictures from 2003 and 2010). On 25 September 2009, it was thought that another of the stacks had fallen, but this was actually one of the smaller stacks of the Three Sisters formation. The rate of erosion at the base of the limestone pillars is approximately 2 cm per year. Due to wave action eroding the cliff face existing headlands are expected to become new limestone stacks in the future.

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The Twelve Apostles

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Note: The above post is reprinted from materials provided by Wikipedia.

The Drowned Apostles was Discovered

May 15, 2016

The Drowned Apostles -GeologyPage — Credit: Tourism Victoria/James Lauritz

Scientists have discovered five more of the iconic Twelve Apostles, the spectacular limestone range of columns that stand off Australia’s southern coast – but the hitch is they are 50 metres under water.

In a surprise geological find, a University of Melbourne PhD student has identified a range of “drowned” limestone stacks in front of a submerged ancient coastal cliff about 6km offshore of the Twelve Apostles on Victoria’s southern coast.

The discovery was made as researcher Rhiannon Bezore was analysing new sonar data collected as part of a project to survey potential reef habitats for sea-life such as crayfish and abalone.

“We are calling them the Drowned Apostles because if you had stood on this ancient cliff face over 20,000 years ago they would have looked largely the same as the current Twelve Apostles,” says University of Melbourne coastal geographer David Kennedy, who is supervising Ms Bezore’s PhD work.

It is the first time such stacks have been found preserved below the sea. And they simply shouldn’t be there.

Ordinarily such structures should have been completely eroded before being submerged by rising sea levels. According to Associate Professor Kennedy, the most likely explanation is that around 20,000 years ago, at the end of the last ice age, sea levels rose so fast as the ice melted that the stacks were simply swamped in place.

A geographic image of the Drowned Apostles – the tallest standing nearly 7m – with the submerged cliff face behind them. Credit: Rhiannon Bezore.

Unlike their famous surface cousins, the tops of the “Drowned Apostles” are flattened, suggesting the softer rock at the top was eroded away quickly by the rising waters, effectively shaving off their tops.

“Sea levels probably rose at the end of the last ice age so quickly that the sea just ran across the top of these things without knocking them over,” says Associate Professor Kennedy, from the School of Geography.

“It is amazing that they survived.”

When Associate Professor Kennedy says the sea level rise was rapid he is talking in geological terms and not in terms of sudden catastrophic waves. Nevertheless he says the find suggests that sea levels back then rose by about five-to-ten times the current rate of 2.3mm a year along the Victorian coast, driven by the sheer size of the ice melt.

“When we go into an ice age it is a very slow freezing process, but when it decides to melt it generally does it quite quickly,” he said.

He says the sea level rise would have been readily noticeable within a generation to Aborigines living along the original coastline.

The research has been published in the US-based Journal of Coastal Research and presented at the International Coastal Symposium at Coogee in Sydney.

The “drowned” stacks are just like the Twelve Apostles, consisting of limestone that had been carved out by erosion from softer surrounding rock.

“If you had stood on that ancient cliff line they would have looked similar to the current Apostles, but when sea levels rose the sea went straight across the top of them,” Associate Professor Kennedy says.

In the process their height was worn down by erosion well below the height of the Twelve Apostles, suggesting that the Drowned Apostles had stood for much longer under eroding conditions before they were submerged still intact. They now stand up to nearly 7m tall compared to the Twelve Apostles that range from 30m to 67m tall.

Ms Bezore, a Californian who came to Australia to work with Associate Professor Kennedy after completing a masters degree at University California Santa Cruz, had been going through the sonar data comparing the existing coastline with the ancient submerged coast as a way to model the location of potential sea-life habitats. When she stumbled across the submerged limestone stacks she recognised them immediately, but doubted what she was seeing.

“I was pretty surprised to see them,” Ms Bezore says. “We had to check with each other on what we were seeing because no one has seen stacks submerged at this sea level before.”

The similarity to the Twelve Apostles was obvious. “It was so close by and of a similar shape and form that there has to be some correlation here,” says Ms Bezore.

The sonar data had been collected using advanced multi-beam sonar technology bolted to the bottom of Deakin University’s $650,000 research vessel the “Yolla” as part of a project to map the ocean floor along Victoria’s coast line. Deakin marine scientist Dr Daniel Ierodiaconou, who is also Ms Bezore’s co-supervisor, has led the mapping project. The data was collected for Parks Victoria and the Port Campbell Marine Park.

“As the drowned Apostles are found in the same geological setting as the current Twelve Apostles, it is reasonable to assume that they were formed under the same geomorphic processes, some 60,000 years apart,” the researchers say in the journal article. “Were it not for the relatively quick submergence of the stacks, they likely would have continued to erode at a similar rate as seen with the modern sea stacks until they collapsed.”

Associate Professor Kennedy said the discovery would add a new point of interest to visiting the Twelve Apostles, allowing people to imagine what the coastline would have been like over 20,000 years ago.

The Twelve Apostles have long been a tourist attraction along the cliffs of Victoria’s “Ship Wreck Coast.” The stacks were originally named the Sow and Piglets, with nearby Mutton Bird Island the “Sow,” but the formation was renamed the Twelve Apostles in 1922, even though there were only eight of them. On July 3, 2005 one of the tallest of the Apostles at about 45 metres high suddenly collapsed leaving seven remaining. While some count eight Apostles by adding in a much smaller stack, Park Victoria is adamant there are just seven.

“To know there are more Drowned Apostles offshore I think will add a whole new dimension to the experience,” says Associate Professor Kennedy.

And with five new apostles under the sea to go with those remaining above the sea, it means we now really do have 12 Apostles.

Video

Note: The above post is reprinted from materials provided by University of Melbourne.

Hang Son Doong “The World’s Largest Caves”

May 14, 2016

Hang Sơn Đoòng also known as Sơn Đoòng cave is a solutional cave in Phong Nha-Kẻ Bàng National Park, Bố Trạch District, Quảng Bình Province, Vietnam. As of 2009 it has the largest known cave passage cross-section in the world, and is located near the Laos–Vietnam border. Inside is a large, fast-flowing subterranean river. It was formed in Carboniferous/Permian limestone.

Discovery

Hang Sơn Đoòng was found by a local man named Hồ Khanh in 1991. The whistling sound of wind and roar of a rushing stream in the cave heard through the entrance as well as the steep descent prevented the local people from entering the cave. Only in 2009 did the cave become internationally known after a group of scientists from the British Cave Research Association, conducted a survey in Phong Nha-Kẻ Bàng from 10 to 14 April 2009. Their progress was stopped by a large, 60-metre (200 ft) high calcite wall, which was named the Great Wall of Vietnam. It was traversed in 2010 when the group reached the end of the cave passage.

Description

According to the Limberts, the main Sơn Đoòng cave passage is the largest known cave passage in the world by volume – 38.4×10⁶ cubic metres (1.36×10⁹ cu ft). It is more than 5 kilometres (3.1 mi) long, 200 metres (660 ft) high and 150 metres (490 ft) wide. Its cross-section is believed to be twice that of the next largest passage, in Deer Cave, Malayasia. The cave runs for approximately 9 kilometres (5.6 mi) and is punctuated by 2 large dolines, which are areas where the ceiling of the cave has collapsed. The dolines allow sunlight to enter sections of the cave and has resulted in the growth of trees as well as other vegetation.

The cave contains some of the tallest known stalagmites in the world, which are up to 70 m tall. Behind the Great Wall of Vietnam were found cave pearls the size of baseballs, an abnormally large size.

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Hang Son Doong “The World’s Largest Caves”

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Map

Reference:
Wikipedia: Hang Sơn Đoòng
Photos from : Telegraph, National Geographic

Further evidence found against ancient ‘killer walrus’ theory

May 14, 2016

Further evidence found against-GeologyPage — Artist restoration of the head of Pelagiarctos thomasi, a fossil walrus from California. Once thought to be a “killer walrus” that ate marine mammals, new tooth enamel research is bolstering the case that it likely had a diet similar modern New Zealand fur seals and sea lions. Credit: Robert Boessenecker

An Otago-led team of scientists using techniques from the field of dentistry is shedding new light on the evolution of walruses, fur seals and sea lions. The researchers have cast further doubt on previous claims that an ancient “killer walrus” was a marine mammal eater.

In a newly published article in the international journal The Science of Nature the multidisciplinary team of researchers report their analysis of the internal structure of tooth enamel in a fossil walrus from California, Pelagiarctos thomasi, and in teeth of modern pinnipeds the New Zealand fur seal and sea lion.

Study co-author Dr Carolina Loch says this was the first time the enamel ultrastructure of fur seals and sea lions, as well as the extinct walrus Pelagiarctos, was studied using scanning electron microscopy.

“Pelagiarctos was originally thought to have been a “killer walrus” that fed on large prey such as other marine mammals, but we found it has an enamel layer reasonably similar to that of modern New Zealand fur seals and sea lions, which are fish and squid eaters,” Dr Loch says.

The enamel structure the researchers identified in Pelagiarctos meant the walrus was unlikely to be up to crunching through large bones without cracking its teeth — suggesting that it was a dietary generalist like the modern New Zealand pinnipeds studied, she says.

Dr Loch says the study showed how using techniques and methods commonly employed in dentistry can answer questions with broader implications in the biology and evolution of animal species.

“Features and structures of the enamel layer have long been associated with differences in diet and tooth usage among animals, and can also help in the understanding the relationships among fossil and living species.

“Teeth are not only the focus of modern dentistry, but also valuable tools for biologists, archaeologists and paleontologists,” Dr Loch says.

The study was conducted by Dr Loch, research fellow at the University of Otago’s Sir John Walsh Research Institute, Faculty of Dentistry (and Otago alumna — Department of Geology and Faculty of Dentistry); Dr Robert Boessenecker, College of Charleston USA (and Otago alumni — Department of Geology); Dr Morgan Churchill (New York Institute of Technology College of Osteopathic Medicine, USA) and the late Professor Jules Kieser (Otago Faculty of Dentistry) — who is always remembered for his prolific multidisciplinary dental research.

A 2013 paper by Drs Boessenecker and Churchill was the first to cast doubt on the “killer walrus” claims and the latest findings bolster their case, Dr Loch says.

Reference:
Carolina Loch, Robert W. Boessenecker, Morgan Churchill, Jules Kieser. Enamel ultrastructure of fossil and modern pinnipeds: evaluating hypotheses of feeding adaptations in the extinct walrus Pelagiarctos. The Science of Nature, 2016; 103 (5-6) DOI: 10.1007/s00114-016-1366-z

Note: The above post is reprinted from materials provided by University of Otago.

New Ice Age knowledge

May 14, 2016

An international team of researchers headed by scientists from the Alfred Wegener Institute has gained new insights into the carbon dioxide exchange between ocean and atmosphere, thus making a significant contribution to solving one of the great scientific mysteries of the ice ages. In the past 800,000 years of climate history, the transitions from interglacials and ice ages were always accompanied by a significant reduction in the carbon dioxide content in the atmosphere. It then fell from 280 to 180 ppm (parts per million). Where this large amount of carbon dioxide went to and the processes through which the greenhouse gas reached the atmosphere again has been controversial until now. The scientists have now managed to locate a major carbon dioxide reservoir at a depth of 2000 to 4300 metres in the South Pacific and reconstruct the details of its gas emission history. Their new findings have been published open access in the scientific journal Nature Communications.

The southern Pacific Ocean is regarded as one of the largest ventilation windows of the world oceans. This is where the global conveyor belt of ocean currents transports the carbon-rich water from great depths to the surface of the sea for a short time. The gas concentration balance between water and air takes place where the two meet. This usually means that the carbon-rich water masses release the greenhouse gas carbon dioxide they had stored into the atmosphere, thus contributing to the greenhouse effect and the warming of the earth.

But what happened with this oceanic window during the last ice age and during the transition to the current warm period? When there was no ventilation, what happened to the carbon-rich water from the depths? With these key questions in mind, the international team of researchers consisting of geologists, geochemists and modellers analysed sediment cores from the South West Pacific.

The reason why the samples were taken in this marine region was as follows: The atmospheric carbon dioxide curve known from ice cores shows that at the end of the last ice age large amounts of “old” carbon dioxide were released into the atmosphere. Its old age means that this carbon dioxide comes from a reservoir that had not been in contact with the atmosphere for a long period of time. From a climate historical perspective the most likely place where the carbon dioxide is hidden is therefore the oceanic deep water. Most of it is in the Pacific, and it contains around 60 times more carbon than the pre-industrial atmosphere.

The examined sediment samples come from water depths of 830 to 4300 metres; they go back 35000 years and contained calcareous shells of single-celled foraminifera that live on the seafloor and are important for climate reconstructions. The calcareous shells were radiocarbon dated (14C) and thus provided information about the age of the above-mentioned water mass where the organisms lived, and about the period in which there was no exchange between this water mass and the atmosphere. “The older a water mass, the more carbon dioxide it stores, because bound carbon in the form of animal and plant remains constantly trickles down from the surface,” says Dr Thomas Ronge, lead author of the study and geologist at the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI).

This allowed him and his colleagues to find out that the water of the Southern Ocean approx. 20,000 years ago was strongly stratified and the individual water masses hardly intermixed at all. “Our results were surprising and indicated that the deep South Pacific during this glacial period was not only augmented with old carbon dioxide from the decomposition of organic material, but also as a result of eruptions of submarine volcanoes,” Thomas Ronge explains.

On the basis of these new climate data, the AWI researchers are now able to draw the following picture of the ice age ocean 20000 years ago. “We know from other studies that it is likely that during the transition from interglacial to ice age a large sea ice cover formed on the Antarctic Ocean, which closed the oceanic ventilation window. At the same time, the Southern Westerly Winds moved northwards, so that the buoyancy in the Southern Ocean was reduced and only a small amount of deep water reached the surface,” Thomas Ronge explained.

In fact, deep ocean circulation slowed down to such an extent that the heavy, saline water mass below a depth of 2000 metres was not in contact with the surface for almost 3000 years. “During this time, so much bound carbon in the form of animal and algae remains trickled down from the more intermixed sea surface into the deep water layer that we were able to identify it as the major carbon reservoir that we have looked for so intensively,” says Thomas Ronge. The data also showed that the already old age of the water masses was artificially increased from about 3000 to 8000 years as a result of the injected volcanic carbon.

At the end of the last ice age, when the Antarctic sea ice decreased again, the westerly winds returned to the south and the ocean circulation picked up speed again, the deep water enriched with carbon reached the surface of the sea. “The water then released large amounts of the stored carbon in the form of old carbon dioxide into the atmosphere and thus significantly accelerated the warming of the planet,” says Thomas Ronge.

Today, carbon-rich deep water around the Antarctic is transported to the sea surface as well. Since the industrialisation, however, carbon dioxide concentration in the atmosphere has increased to more than 400 ppm, which means that the Southern Ocean is not currently emitting carbon dioxide, and instead is absorbing the greenhouse gas, which in turn slightly dampens global warming. Previous model studies indicate, however, that this ratio may reverse in the coming centuries.

There is evidence to suggest that the current climate change causes westerly winds to increase, which increasingly transports carbon dioxide-rich deep water to the surface. “Examining the sensitivity of this system to different time scales and which processes are particularly important is currently a focal point of several research groups at the Alfred Wegener Institute and worldwide,” says Prof Ralf Tiedemann, co-author of the study and head of the department of geosciences at the AWI.

Reference:
T. A. Ronge, R. Tiedemann, F. Lamy, P. Köhler, B. V. Alloway, R. De Pol-Holz, K. Pahnke, J. Southon, L. Wacker. Radiocarbon constraints on the extent and evolution of the South Pacific glacial carbon pool. Nature Communications, 2016; 7: 11487 DOI: 10.1038/ncomms11487

Note: The above post is reprinted from materials provided by Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research.

The granite of Sierra de Guadarrama requests designation of origin

May 14, 2016

The granite of Sierra de Guadarrama-GeologyPage — Alpedrete granite seen under a petrographic microscope. The main minerals are indicated: quartz (Qz), potassium feldspar (K-Fsp), plagioclase (Pl) and biotite (Bt). Credit: D. M. Freire-Lista/IGEO (CSIC-UCM)

The Puerta de Alcalá, the Prado Museum and the monastery of El Escorial are some of the monuments built with berroqueña stone, the traditional name of the high-quality Madrid granites which are also used in airports, for example Athens, and modern shopping centres around the world such as China. As with renowned wines and cheeses Spanish geologists now propose to the International Union of Geological Sciences that these granites should become part of the list of natural stones with designation of origin because of their cultural and economic importance.

The International Union of Geological Sciences (IUGS) has created the Global Heritage Stone Province distinction to recognize those provinces or regions of the world where stones of great historical and economic importance are extracted. This international geological recognition is similar to the designations of origin for food and drinks.

One of the first candidate regions for the award is the extraction area of the Sierra de Guadarrama mountain range, producer of the traditionally named ‘berroqueña stone’, the stone material most used historically in Madrid (Spain). Monuments such as as the monastery of El Escorial, the Royal Palace, Puerta de Alcalá, the National Library, the Almudena Cathedral, the Bank of Spain, the Puerta del Sol square and the Reina Sofia Museum are built with this granite.

In addition, in recent years berroqueña stone has crossed borders. Examples include the airport terminals in Athens (Greece) and Cork (Ireland), the British consulate in Hong Kong, various shopping malls in China and modern buildings in Israel, which have been built with berroqueña stone.

“The aim of the candidacy is to achieve international recognition of the granite quarries of the Sierra de Guadarrama mountain range, so important in cultural heritage, to enhance their production and export,” states David M. Freire-Lista, researcher at the Institute of Geosciences (a joint centre of the CSIC and Complutense University of Madrid) and promoter of the project. The details are published in the journal, Geoscience Canada.

The Alpedrete, Zarzalejo and Colmenar Viejo quarries are the ones that have traditionally provided this stone, although in recent years they have been joined by Cadalso de los Vidrios and La Cabrera. Production increased steadily from the 1980s until 2008 when an economic crisis that has adversely affected the sector began.

“Achieving the Global Heritage Stone Province accreditation for this region would promote trade in this historically important and sought-after material, promoting employment in rural areas of the Sierra de Madrid mountains, where the supply is guaranteed by the extensive reserves of high quality and durable granite. I hope that after this candidacy, this region will be nominated for this distinction, said Freire-Lista. In 2016, the Spanish region nominated as GHSP is the Iberian Roofing Slate Province.

For the drafting of this candidacy the authors have compiled historical documentation and have characterized the granites from different quarries. The samples were subjected to artificial ageing accelerated by freeze-thaw and heat shock processes. Petrographic and petrophysical analyses were also performed to determine their response to deterioration.

“The variation in density, porosity, speed of propagation of ultrasound waves and colour of the artificially aged granites have served to demonstrate their high quality, certifying their excellent characteristics, strength and durability,” said the geologist, who concludes: “These granites are suitable for use in architectural heritage restoration and new construction in any climate.”

Alpedrete granite is a candidate for Global Heritage Stone Resource
In addition to the Global Heritage Stone Province, the IUGS has also created another category called Global Heritage Stone Resource (GHSR), which recognizes specific building stones used in heritage and which have a potential to be marketed internationally.

In 2015 the stone from Portland (England), which was used to build Buckingham Palace in London and the United Nations building in New York, became the first stone to be declared a Global Heritage Stone Resource.

Alpedrete granite from Sierra de Guadarrama is nominated for the upcoming 2016 GHSR designation together with other national nominated, such as Villamayor stone from Salamanca, Verde Granada serpentine, and others international candidates, such as Pietra Mar del Plata (Argentina); Sydney sandstone (Australia); marble from Carrara, Pietra Serena and Rosa Beta granite (Italy); Dala (?lavaen) porphyries, Hallandia gneiss and Kolmarden Serpentine marble (Sweden); Larvikete (Norway); Lede stone and Petit granit (Belgium); Steatite and Schist from Minas Gerais State (Brazil); Estremoz marble and Oporto granite (Portugal) and Podpec limestone from Slovenia.

Granite represents 20.8% of the total volume of ornamental rock exported from Spain. In addition to Madrid, the most important producing areas are in Galicia, Extremadura and Avila. According to the Spanish Federation of Natural Stone, its trade in 2009 gave employment to about 24,300 people in Spain.

References:

D. M. Freire-Lista, R. Fort. “The Piedra Berroqueña Region: Candidacy for Global Heritage Stone Province Status”. Geoscience Canada 43: 43-52, 2016.
D. M. Freire-Lista, R. Fort, M. J. Varas-Muriel. “Alpedrete Granite (Spain). A Nomination for the “Global Heritage Stone Resource” Designation”. Episodes-Journal of International Geoscience 38(2): 106-113, 2015.

Note: The above post is reprinted from materials provided by FECYT – Spanish Foundation for Science and Technology.

Retreat of the ice followed by millennia of methane release

May 14, 2016

Retreat of the ice followed-GeologyPage — Scientists discovered a long methane seeping event in the Barents Sea by dating carbonate crusts, such as the one seen in the upper right corner. Credit: CAGE

Scientists have calculated that the present day ice sheets keep vast amounts of climate gas methane in check. Ice sheets are heavy and cold, providing pressure and temperatures that contain methane in form of ice-like substance called gas hydrate. If the ice sheets retreat the weight of the ice will be lifted from the ocean floor, the gas hydrates will be destabilised and the methane will be released.

Studies conducted at CAGE have previously shown that ice sheets and methane hydrates are closely connected, and that release of methane from the seafloor has followed the retreat of the Barents Sea ice sheet some 20,000 years ago. But is all such release of the potent climate gas bound to be catastrophic?

Not necessarily, according to a new study published in Nature Communications. It shows that the methane was indeed released as the ice sheets retreated. However the seepage did not occur in one major pulse, but over a period of 7000 to 10000 years following the initial release.

“The release was too slow to significantly impact the concentration of methane in the atmosphere.” says researcher and project leader Aivo Lepland at Norwegian geological Survey (NGU) and CAGE.This may help explain why we have yet to discover a signal for such events in the various climate records of the past.

Radioactive material tells time

A new and groundbreaking method of dating carbonate rocks has been used to come to this conclusion. The seepage of methane over a long period of time created perfect conditions for formation of a special type of rock called authigenic carbonate crust. This could than be dated by scientists by a using a radiometric technique to measure natural decay of uranium to thorium.

“We have used carbonate crusts that form just below the sea-floor. They are a direct result of the oxidation of methane moving upwards though the sediment layers from deeper reservoirs. The chemical composition of the crust tells us that the source fluid was methane-rich, and the uranium-thorium dating tells us when this methane release happened.” explains lead author of the study Antoine Cremiere, post.doc at NGU/CAGE.

Knowledge of the timescales of gas hydrate dissociation and subsequent methane release are critical in understanding the impact of marine gas hydrates on the ocean-atmosphere system, says Shyam Chand, researcher at NGU/CAGE.

Paper reference: Cremiere et. al. Timescales of methane seepage on the Norwegian margin following collapse of the Scandinavian Ice Sheet. Nature Communications 7, May 2016.

Video

Reference:
Antoine Crémière, Aivo Lepland, Shyam Chand, Diana Sahy, Daniel J. Condon, Stephen R. Noble, Tõnu Martma, Terje Thorsnes, Simone Sauer, Harald Brunstad. Timescales of methane seepage on the Norwegian margin following collapse of the Scandinavian Ice Sheet. Nature Communications, 2016; 7: 11509 DOI: 10.1038/ncomms11509

Note: The above post is reprinted from materials provided by CAGE – Center for Arctic Gas Hydrate, Climate and Environment.

Downpatrick Head, County Mayo, Ireland

May 13, 2016

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Just a few miles north of Ballycastle village, County Mayo, is the the windswept outcrop of Downpatrick Head. This is the perfect place to park up and stretch your legs with an invigorating coastal walk.

The name Downpatrick is derived from a time when St Patrick himself founded a church here. You can still see the ruins of the church building, a stone cross and holy well here today. This was once a popular pilgrim destination, and today the crowds still gather here on the last Sunday of July – known as Garland Sunday – to hear mass at this sacred site.

The St Patrick connections don’t end there though. Gazing out to sea, you’ll no doubt spot the small collection of islands called the Staggs of Broadhaven, but you’ll also see a lone sea-stack standing close to the edge of the cliffs. This sea-stack is called Dún Briste (broken fort). Local legend says that when a pagan chieftain refused to convert to Christianity, St Patrick struck the ground with his crozier, splitting a chunk of the headland off into the ocean, with the chieftain on top! The sea stack is beautiful to behold because you can see the layers upon layers of multi-coloured rock strata.

Megalithic mind frame

Fast-forward through the centuries and Downpatrick Head became a lookout post during WWII. You can still see the stone building there today. Another intrigue of the area is Poll Na Seantainne: this is a spectacular blowhole that plummets down to the tempestuous ocean below.

While in the area make sure to take the short drive out to visit the Céide Fields Visitor Centre in Ballycastle. The Céide Fields is the oldest known Stone Age field system in Europe. The remains of ancient stonewalls, settlements and megalithic tombs have been preserved here thanks to a protective bog environment. Truly awe-inspiring stuff.

With legs fully stretched and minds expanded, it’s time to hit the road again and get back on the Wild Atlantic Way.

Geographical coordinates: Latitude 54° 19′ 33.49; longitude 9° 20′ 44.45 (note, if you use your car’s GPS to go directly to this point, you may not always remain on the Wild Atlantic Way route.)

Photos

Downpatrick Head

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Map

Reference:
Ireland: Downpatrick Head, County Mayo
Geological Survey of Ireland

The evolution of giants “Sauropod Dinosaurs”

May 13, 2016

The evolution of giants -GeologyPage — The sauropod Apatosaurus louisae, Carnegie Museum. Credit: Tadek Kurpaski

Sauropod dinosaurs are some of the most notoriously recognisable animals. With their whiplash tails, and long searching necks, they are the biggest terrestrial vertebrates ever to walk the Earth.

One factor that has received much attention from a range of scientific disciplines is the evolution of gigantism: how and why did sauropods get so damn big? Many sauropods were up to an order of magnitude than the biggest mammals, and they had a distinct body plan to accompany and accommodate this, with stocky, columnar limbs and a tank-like torso.

But what does ‘big’ mean? And how do you measure ‘big’ in fossil species?

Size is a multi-dimensional factor. For example, what is bigger, a 3 meter long snake, or a 3 metre tall giraffe? They are both equally ‘big’ in one dimension, and ‘bigger’ than the other based on it. What about a one tonne elephant – is that bigger than a 3 metre tall giraffe or a 3 metre long snake?

Size takes on different dimensions, and is important for a number of reasons. Size confers a survival advantage on an animal, for example – the bigger you are, the less risk you’re at from predation. Unless your predators grow equally in size too, in which case you get predator-prey escalation in a sort of arms race. Similarly, small size can often be a good thing too – imagine a 15 metre long sauropod trying to fly!

So big is complicated, and when we’re talking about sauropods, ‘big’ or ‘gigantic’ can refer to their enormous height, length, or body mass. If the fossil record were kind, we would be able to calculate these things easily. But as readers of this blog will know, the fossil record is rarely kind, and often cruel.

We often only have scraps of dinosaur, a bone here or there, perhaps a few articulated skull elements or a limb. Very rarely do we get a complete dinosaur which we can accurately estimate size from. So how do we accurately estimate the size of sauropods, and place this into an evolutionary context?

Karl Bates from the University of Liverpool (UK) and an international team of colleagues set out to answer these question using what are informally known as ‘kick ass’ methods.

Previously, size has been estimated in extinct dinosaurs by using proxies, such as the length of the femur or the total length of the body. From this, we generally know that sauropods evolved from smaller, bipedal animals into the quadrupedal titans we perhaps know best. Previous studies have estimated the mass just of one or two exceptional sauropod species, which doesn’t tell us much about evolutionary trends, and is more about understanding evolutionary limits, or sometimes even just something for a bit of media grabby attention. Bates and the team sampled sauropod species from across their evolutionary tree, totalling 17 species in all.

Not only did they have a much wider temporal and phylogenetic coverage than all previous studies, but they also used really cool methods based on automated computational volumetric to estimate their body sizes.

Fire the “laser”

They used a long-range laser scanning technique and digital photogrammetry to create computer models of entire sauropod skeletons. To reconstruct the fleshy parts of each animal, a convex hull approach was used which fits three-dimensional polygons around different sections of the skeleton to digitally represent the volume of each animal. This provides a baseline minimal body size estimate, and the team played with this to test the sensitivity of results by increasing the volume of the convex hulls to represent different body proportions. As such, estimates of body size contain large error bars, which is needed for calculations like this in which there is a lot of potential uncertainty.

What the team found is perhaps intuitive, but cool nonetheless. It seems that all major changes in body size within sauropods and their ancestors (sauropodomorphs) are related to major macroevolutionary events in the history of the group.

In the Middle Triassic (245-230 million years ago), when dinosaurs were just getting going, there is evidence for shift in the centre of mass of saurischian dinosaurs (early theropods and sauropodomorphs). This tail-wards shift in centre of mass seems to be associated with the evolution of bipedalism in these early dinosaurs.

However, this change was reversed by the Late Triassic, as sauropods became more graviportal and took to four legs to support their increasing body sizes during the Early to Middle Jurassic. This constraint to using four limbs to walk is called ‘obligate quadrupedalism’.

Later on in their evolution during the Late Jurassic (around 161 million years ago), this reversal becomes more prominent as the centre of mass moved more towards the skull, particularly striking in the titanosauriforms – the sauropod group that included the largest species of all (in case you didn’t get that from the name..)

Centre of mass shifts towards the front end of the animal are each associated with lengthening of the neck, a trait that was probably one of the most important factors in the evolution of gigantism in sauropods. A longer neck gives an animal a greater ‘feeding envelope’ and it becomes more efficient in gathering food. Additionally, it means you can reach food that other smaller herbivores are incapable of. And trees thought they were so smart..

These shifts are also related to changes in locomotory habit and environmental distributions in titanosaurs. For example, some sauropods had what is called a ‘narrow gauge’ stance while others had a ‘wide gauge’, which relates to the relative distances between pairs of legs beneath the torso. Wider gauge trackways are those in which the legs are planted further away from the midline of the animal. The evolution of this ‘wide gauge’ stance is coincident in time with the evolution of a more cranial-positioned centre of mass, and development of a greater neck length.

Also, it seems that some subgroups of sauropods preferred to inhabit coastal environments, while others dwelled more inland in freshwater habitats like lakes and rivers. Whether this environmental differentiation had a role to play in the evolution of sauropods remains to be seen.

What we do know now though is that estimating the size of dinosaurs is complicated! But researchers are making great strides to measure this, while understanding the limits of what current technology can tell us. By doing so, they’re slowly unlocking the constraints placed on the evolution of life, and that’s pretty awesome.

Reference:
Karl T. Bates et al. Temporal and phylogenetic evolution of the sauropod dinosaur body plan, Royal Society Open Science (2016). DOI: 10.1098/rsos.150636

Note: The above post is reprinted from materials provided by Public Library of Science.

Found: Surviving evidence of Earth’s formative years

May 13, 2016

Found Surviving evidence of Earth-GeologyPage — This is a photograph of Baffin Island, where a research team was able find a geochemical signature of material left over from the early melting events that accompanied Earth’s formation. Credit: Courtesy of Don Francis of McGill University

New work from a team including Carnegie’s Hanika Rizo and Richard Carlson, as well as Richard Walker from the University of Maryland, has found material in rock formations that dates back to shortly after Earth formed. The discovery will help scientists understand the processes that shaped our planet’s formative period and its internal dynamics over the last 4.5 billion years. It is published by Science.

Earth formed from the accretion of matter surrounding the young Sun. The heat of its formation caused extensive melting of the planet, leading Earth to separate into two layers when the denser iron metal sank inward toward the center, creating the core and leaving the silicate-rich mantle floating above.

Over the subsequent 4.5 billion years of Earth’s evolution, convection in Earth’s interior, like water boiling on a stove, caused deep portions of the mantle to rise upwards, melt, and then separate once again by density. The melts, since they were less dense than the unmelted rock, rose to form Earth’s crust, while the denser residues of the melting sank back downward, altering the mantle’s chemical composition in the process.

The mantle residues of crust formation were previously believed to have mixed back into the mantle so thoroughly that evidence of the planet’s oldest geochemical events, such as core formation, was lost completely.

However, the research team–which also included Sujoy Mukhopadhyay and Vicky Manthos of University of California Davis, Don Francis of McGill University, and Matthew Jackson, a Carnegie alumnus now at University of California Santa Barbara–was able find a geochemical signature of material left over from the early melting events that accompanied Earth’s formation. They found it in relatively young rocks both from Baffin Island, off the coast of northern Canada, and from the Ontong-Java Plateau in the Pacific Ocean, north of the Solomon Islands.

These rock formations are called flood basalts because they were created by massive eruptions of lava. The solidified lava itself is only between 60 and 120 million years old, depending on its location. But the team discovered that the molten material from inside the Earth that long ago erupted to create these plains of basaltic rock owes its chemical composition to events that occurred over 4.5 billion years in the past.

Here’s how they figured it out:

They measured variations in these rocks of the abundance of an isotope of tungsten–the same element used to make filaments of incandescent light bulbs. Isotopes are versions of an element in which the number of neutrons in each atom differs from the number of protons. (Each element contains a unique number of protons.) These differing neutron numbers mean that each isotope has a slightly different mass.

Why tungsten? Tungsten contains one isotope of mass 182 that is created when an isotope of the element hafnium undergoes radioactive decay, meaning its elemental composition changes as it gives off radiation. The time it takes for half of any quantity of hafnium-182 to decay into tungsten-182 is 9 million years. This may sound like a very long time, but is quite rapid when it comes to planetary formation timescales. Rocky planets like Earth or Mars took about 100 million years to form.

The team determined that the basalts from Baffin Island, formed by a 60-million-year-old eruption from the mantle hot-spot currently located beneath Iceland, and the Ontong-Java Plateau, which was formed by an enormous volcanic event about 120 million years ago, contain slightly more tungsten-182 than other young volcanic rocks.

Because all the hafnium-182 decayed to tungsten-182 during the first 50 million years of Solar System history, these findings indicate that the mantle material that melted to form the flood basalt rocks that the team studied originally had more hafnium than the rest of the mantle. The likely explanation for this is that the portion of Earth’s mantle from which the lava came had experienced a different history of iron separation than other portions of the mantle (since tungsten is normally removed to the core along with the iron.)

It was a surprise to the team that such material still exists in Earth’s interior.

“This demonstrates that some remnants of the early Earth’s interior, the composition of which was determined by the planet’s formation processes, still exist today,” explained lead author Rizo, now at Université du Québec à Montréal.

“The survival of this material would not be expected given the degree to which plate tectonics has mixed and homogenized the planet’s interior over the past 4.5 billion years, so these findings are a wonderful surprise,” added Carlson, Director of Carnegie’s Department of Terrestrial Magnetism.

The team’s discovery offers new insight into the chemistry and dynamics that shaped our planet’s formative processes. Going forward, scientists will have to hunt for other areas showing outsized amounts of tungsten-182 with the hope of illuminating both the earliest portion of Earth’s history as well as the place in Earth’s interior where this ancient material is stored.

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Caption: Photographs from Baffin Island fieldwork, courtesy of Don Francis of McGill University.

Note: The above post is reprinted from materials provided by Carnegie Institution for Science.

How algae could save plants from themselves

May 13, 2016

How algae could save plants-GeologyPage — The algal pyrenoid could be the key to increasing crop yields. A pyrenoid (blue) is seen in a cross-section of an algal cell by false-colored electron microscopy. The pyrenoid sits inside the chloroplast (green), which harvests light energy to drive carbon fixation. Credit: Image is courtesy of Moritz Meyer.

Algae may hold the key to feeding the world’s burgeoning population. Don’t worry; no one is going to make you eat them. But because they are more efficient than most plants at taking in carbon dioxide from the air, algae could transform agriculture. If their efficiency could be transferred to crops, we could grow more food in less time using less water and less nitrogen fertilizer.

New work from a team led by Carnegie’s Martin Jonikas published in Proceedings of the National Academy of Sciences reveals a protein that is necessary for green algae to achieve such remarkable efficiency. The discovery of this protein is an important first step in harnessing the power of green algae for agriculture.

It all starts with the world’s most abundant enzyme, Rubisco.

Rubisco “fixes” (or converts) atmospheric carbon dioxide into carbon-based sugars, such as glucose and sucrose, in all photosynthetic organisms on the planet. This reaction is central to life on Earth as we know it, because nearly all the carbon that makes up living organisms was at some point “fixed” from the atmosphere by this enzyme. The rate of this reaction limits the growth rate of many of our crops, and many scientists think that accelerating this reaction would increase crop yields.

The funny thing about Rubisco is that it first evolved in bacteria about 3 billion years ago, a time when the Earth’s atmosphere had more abundant carbon dioxide compared to today. As photosynthetic bacteria became more and more populous on ancient Earth, they changed our atmosphere’s composition.

“Rubisco functioned very efficiently in the ancient Earth’s carbon dioxide-rich environment,” Jonikas said. “But it eventually sucked most of the CO2 out of the atmosphere, to the point where CO2 is a trace gas today.”

Rubisco is quite literally a victim of its own success. CO2 makes up only about 0.04 percent of molecules in today’s atmosphere. In this low concentration of CO2, Rubisco works extremely slowly, which limits the growth rates of many crops.

It turns out that algae have evolved a way to make Rubisco run faster. It’s called the pyrenoid. Think of it as a turbocharger for carbon fixation.

The pyrenoid is a tiny compartment inside the cell that is packed with Rubisco and is surrounded by a sheath of starch. Under a microscope, a pyrenoid looks like a spherical bubble inside the cell. Its job is to concentrate carbon dioxide around Rubisco so that Rubisco can run faster.

A pyrenoid provides such a tremendous growth advantage that nearly all algae in the oceans have one. About a third of the planet’s carbon fixation is thought to happen in pyrenoids, yet we know almost nothing about how these structures are formed at a molecular level. Such a molecular understanding is needed before researchers can attempt to engineer pyrenoids into crops, which is expected to enhance crop yields by as much as 60 percent.

The research team focused on a fundamental decades-old mystery: what causes Rubisco to cluster at the core of the pyrenoid?

Jonikas and his team discovered that in their model alga Chlamydomonas, this clustering of Rubisco is mediated by a protein they called EPYC1 for Essential Pyrenoid Component 1. They found that EPYC1 bound with Rubisco and packaged it into the matrix of proteins that forms the pyrenoid’s interior. What’s more, proteins similar to EPYC1 are found in most pyrenoid-containing algae, and are not found in algae that lack these structures.

“A lot of additional work is needed to fully understand EPYC1 and pyrenoids, but our findings are a first step toward engineering algal carbon-capture efficiency into crops,” Jonikas said.

The research team also included Carnegie’s Luke Mackinder (the lead author), Vivian Chen, Elizabeth Freeman Rosenzweig, Leif Pallesen, Gregory Reeves, and Alan Itakura. The project was a close collaboration with Moritz Meyer, Madeline Mitchell, Oliver Caspari, and Howard Griffiths of the University of Cambridge; Tabea Mettler-Altmann, Frederik Sommer, Timo Mühlhaus, Michael Schroda and Mark Stitt of the Max Planck Institute of Molecular Plant Physiology; Robyn Roth and Ursula Goodenough of Washington University St. Louis; and Stefan Geimer of University of Bayreuth.

Note: The above post is reprinted from materials provided by Carnegie Institution for Science.

New research estimates probability of mega-earthquake in the Aleutians

May 13, 2016

New research estimates probability-GeologyPage — The only well-documented paleotsunami deposit in Hawai’i from the 16th century is on Kaua`i. The Makauwahi sinkhole, on the side of a hardened sand dune, is viewed toward the southeast from an apparent altitude of 342 m. Inset photos show two of the wall edges, indicating the edges of the sinkhole. The east wall (left) is 7.2 m above mean sea level, and about 100 m from the ocean. Note for scale the people in the right image. Credit: R. Butler (left), Gerard Fryer (right), GoogleMaps (background). Figure from Butler et al., 2014.

A team of researchers from the University of Hawai’i at Mānoa (UHM) published a study this week that estimated the probability of a Magnitude 9+ earthquake in the Aleutian Islands–an event with sufficient power to create a mega-tsunami especially threatening to Hawai’i. In the next 50 years, they report, there is a 9% chance of such an event. An earlier State of Hawai’i report (Table 6.12) has estimated the damage from such an event would be nearly $40 billion, with more than 300,000 people affected.

Earth’s crust is composed of numerous rocky plates. An earthquake occurs when two sections of crust suddenly slip past one another. The surface where they slip is called the fault, and the system of faults comprises a subduction zone. Hawai’i is especially vulnerable to a tsunami created by an earthquake in the subduction zone of the Aleutian Islands.

“Necessity is the mother of invention,” said Rhett Butler, lead author and geophysicist at the UHM School of Ocean and Earth Science and Technology (SOEST). “Having no recorded history of mega tsunamis in Hawai’i, and given the tsunami threat to Hawai’i, we devised a model for Magnitude 9 earthquake rates following upon the insightful work of David Burbidge and others.”

Butler and co-authors Neil Frazer (UHM SOEST) and William Templeton (now at Portland State University) created a numerical model based only upon the basics of plate tectonics: fault length and plate convergence rate, handling uncertainties in the data with Bayesian techniques.

To validate this model, the researchers utilized recorded histories and seismic/tsunami evidence related to the 5 largest earthquakes (greater than Magnitude 9) since 1900 (Tohoku, 2011; Sumatra-Andaman, 2004; Alaska, 1964; Chile, 1960; and Kamchatka, 1952).

“These five events represent half of the seismic energy that has been released globally since 1900,” said Butler. “The events differed in details, but all of them generated great tsunamis that caused enormous destruction.”

To further refine the probability estimates, they took into account past (prior to recorded history) tsunamis–evidence of which is preserved in geological layers in coastal sediments, volcanic tephras, and archeological sites.

“We were surprised and pleased to see how well the model actually fit the paleotsunami data,” said Butler.

Using the probability of occurrence, the researchers were able to annualize the risk. They report the chance of a Magnitude 9 earthquake in the greater Aleutians is 9% ± 3% in the next 50 years. Hence the risk is 9% of $40 billion, or $3.6 billion. Annualized, this risk is about $72 million per year. Considering a worst-case location for Hawai’i limited to the Eastern Aleutian Islands, the chances are about 3.5% in the next 50 years, or about $30 million annualized risk. In making decisions regarding mitigation against this $30-$72 million risk, the state can now prioritize this hazard with other threats and needs.

The team is now considering ways to extend the analysis to smaller earthquakes, Magnitude 7-8, around the Pacific.

Reference:
Rhett Butler, L. Neil Frazer, William J. Templeton, Bayesian Probabilities for Mw 9.0+ Earthquakes in the Aleutian Islands from a Regionally Scaled Global Rate. DOI: 10.1002/2016JB012861

Note: The above post is reprinted from materials provided by University of Hawaii at Manoa.

Satellite Data Could Help Reduce Flights Sidelined by Volcanic Eruptions

May 13, 2016

Satellite Data Could Help Reduce-GeologyPage — Artist’s concept of ash and volcanic residue making its way around the Earth. Credit: NASA

A volcano erupting and spewing ash into the sky can cover nearby areas under a thick coating of ash and can also have consequences for aviation safety. Airline traffic changes due to a recent volcanic eruption can rack up unanticipated expenses to flight cancellations, lengthy diversions and additional fuel costs from rerouting.

Airlines are prudently cautious, because volcanic ash is especially dangerous to airplanes, as ash can melt within an operating aircraft engine, resulting in possible engine failure. In the aftermath of a volcanic eruption, airlines typically consult with local weather agencies to determine flight safety, and those decisions today are largely based on manual estimates with information obtained from a worldwide network of Volcanic Ash Advisory Centers. These centers are finding timely and more accurate satellite data beneficial.

Researchers at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, are using already available satellite measurements of sulfur dioxide (SO2), a main components of volcanic emissions, along with the more recent ability to map the location and vertical profiles of volcanic aerosols. Researchers are doing this in a number of ways.

A volcanic cloud contains two kinds of aerosols: sulfuric acid droplets converted from SO2 and silicate volcanic ash. Satellites can detect volcanic ash by observing the scattering of ultraviolet light from the sun. For aviation, volcanic ash is potentially the most deadly because of the danger to aircraft engines. While measurements of aerosol absorption in ultraviolet do not differentiate between the smoke, dust and ash aerosols, only volcanic clouds contain significant abundances of SO2, so satellite measurements of SO2 are especially valuable for unambiguous identification of volcanic clouds.

Knowing both the physical location and the altitude distribution of aerosols in the volcanic cloud allow more accurate forecasts in the days, weeks and months after an eruption. “The capability of mapping the full extent of a three-dimensional structure of a moving volcanic cloud has never been done before,” said Nickolay A. Krotkov, physical research scientist with the Atmospheric Chemistry and Dynamics Laboratory at NASA Goddard.

Researchers are currently making these measurements using the Limb Profiler instrument, part of Ozone Mapping Profiler Suite (OMPS) instrument, currently flying on the joint NASA/National Oceanic and Atmospheric Administration (NOAA))/Department of Defense Suomi National Polar-orbiting Partnership (Suomi NPP) satellite, launched in October 2011.

OMPS is a three-part instrument: a nadir mapper that maps ozone, SO2 and aerosols; a nadir profiler that measures the vertical distribution of ozone in the stratosphere; and a limb profiler that measures aerosols in the upper troposphere, stratosphere and mesosphere with high vertical resolution.

“With the OMPS instrument, the volcanic cloud is mapped as Suomi NPP flies directly overhead and then as it looks back, it observes three vertical slices of the cloud,” said Eric Hughes, a research assistant at the University of Maryland, who is working with Krotkov at NASA Goddard.

Knowing the timing and duration of an eruption, the altitude and amount of the volcanic emissions are critical for an accurate volcanic forecast model being developed at the Goddard Modeling and Assimilation Office. The height of the plume is particularly critical for forecasting the direction of the plume. Even several kilometers of height can make a significant difference in predicting plume movement. More accurate volcanic cloud forecasts could reduce airline cancellations and rerouting costs.

While aviation is a short-term immediate application for volcanic cloud modeling, there are also long-term climate applications. “Sulfate aerosols formed after large volcanic eruptions affect the radiation balance and can linger in the stratosphere for a couple of years,” said Krotkov.

There have been large volcanic eruptions that have contributed to short-term cooling of Earth from the SO2 that reaches the stratosphere, which is what happened following the Philippines Mount Pinatubo eruption in June 1991. During volcanic eruptions, SO2 converts to sulfuric acid aerosols. Now researchers are studying the impacts of deliberately injecting SO2 into the stratosphere to contract the effects of global warming, known as climate intervention.

“Nature gives us these volcanic perturbations and then we can see the impact on climate,” Krotkov said. “These are the short- and long-term consequences of volcanic eruptions that have both aviation and climate applications.”

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Volcano eruptions can wreak havoc on airplanes that fly through the clouds of ash and sulfur dioxide.

Data from NASA earth-observing satellites is improving the ability to detect and forecast the hazard to aviation from volcanic clouds.

Note: The above post is reprinted from materials provided by NASA/Goddard Space Flight Center.

Space mission first to observe key interaction between magnetic fields of Earth and sun

May 13, 2016

Space mission first to observe-GeologyPage — This artist’s rendition shows the four identical MMS spacecraft flying near the sun-facing boundary of Earth’s magnetic field (blue wavy lines). The MMS mission has revealed the clearest picture yet of the process of magnetic reconnection between the magnetic fields of Earth and the sun — a driving force behind space weather, solar flares and other energetic phenomena. Credit: NASA

Most people do not give much thought to the Earth’s magnetic field, yet it is every bit as essential to life as air, water and sunlight. The magnetic field provides an invisible, but crucial, barrier that protects Earth from the sun’s magnetic field, which drives a stream of charged particles known as the solar wind outward from the sun’s outer layers. The interaction between these two magnetic fields can cause explosive storms in the space near Earth, which can knock out satellites and cause problems here on Earth’s surface, despite the protection offered by Earth’s magnetic field.

A new study co-authored by University of Maryland physicists provides the first major results of NASA’s Magnetospheric Multiscale (MMS) mission, including an unprecedented look at the interaction between the magnetic fields of Earth and the sun. The paper describes the first direct and detailed observation of a phenomenon known as magnetic reconnection, which occurs when two opposing magnetic field lines break and reconnect with each other, releasing massive amounts of energy.

The discovery is a major milestone in understanding magnetism and space weather. The research paper appears in the May 13, 2016, issue of the journal Science.

“Imagine two trains traveling toward each other on separate tracks, but the trains are switched to the same track at the last minute,” said James Drake, a professor of physics at UMD and a co-author on the Science study. “Each track represents a magnetic field line from one of the two interacting magnetic fields, while the track switch represents a reconnection event. The resulting crash sends energy out from the reconnection point like a slingshot.”

Evidence suggests that reconnection is a major driving force behind events such as solar flares, coronal mass ejections, magnetic storms, and the auroras observed at both the North and South poles of Earth. Although researchers have tried to study reconnection in the lab and in space for nearly half a century, the MMS mission is the first to directly observe how reconnection happens.

The MMS mission provided more precise observations than ever before. Flying in a pyramid formation at the edge of Earth’s magnetic field with as little as 10 kilometers’ distance between four identical spacecraft, MMS images electrons within the pyramid once every 30 milliseconds. In contrast, MMS’ predecessor, the European Space Agency and NASA’s Cluster II mission, takes measurements once every three seconds–enough time for MMS to make 100 measurements.

“Just looking at the data from MMS is extraordinary. The level of detail allows us to see things that were previously a blur,” explained Drake, who served on the MMS science team and also advised the engineering team on the requirements for MMS instrumentation. “With a time interval of three seconds, seeing reconnection with Cluster II was impossible. But the quality of the MMS data is absolutely inspiring. It’s not clear that there will ever be another mission quite like this one.”

Simply observing reconnection in detail is an important milestone. But a major goal of the MMS mission is to determine how magnetic field lines briefly break, enabling reconnection and energy release to happen. Measuring the behavior of electrons in a reconnection event will enable a more accurate description of how reconnection works; in particular, whether it occurs in a neat and orderly process, or in a turbulent, stormlike swirl of energy and particles.

A clearer picture of the physics of reconnection will also bring us one step closer to understanding space weather–including whether solar flares and magnetic storms follow any sort of predictable pattern like weather here on Earth. Reconnection can also help scientists understand other, more energetic astrophysical phenomena such as magnetars, which are neutron stars with an unusually strong magnetic field.

“Understanding reconnection is relevant to a whole range of scientific questions in solar physics and astrophysics,” said Marc Swisdak, an associate research scientist in UMD’s Institute for Research in Electronics and Applied Physics. Swisdak is not a co-author on the Science paper, but he is actively collaborating with Drake and others on subsequent analyses of the MMS data.

“Reconnection in Earth’s magnetic field is relatively low energy, but we can get a good sense of what is happening if we extrapolate to more energetic systems,” Swisdak added. “The edge of Earth’s magnetic field is an excellent test lab, as it’s just about the only place where we can fly a spacecraft directly through a region where reconnection occurs.”

To date, MMS has focused only on the sun-facing side of Earth’s magnetic field. In the future, the mission is slated to fly to the opposite side to investigate the teardrop-shaped tail of the magnetic field that faces away from the sun.

Reference:
James Burch et al. Electron-Scale Measurements of Magnetic Reconnection in Space. Science, May 13, 2016 DOI: 10.1126/science.aaf2939

Note: The above post is reprinted from materials provided by University of Maryland.

Subsidence on the Gulf Coast: Old Problem, New Challenges

MONITORING GROUNDWATER SUPPLIES NEAR OHIO FRACKING SITES

MONITORING FRACKING IN COLORADO AND TEXAS

Name

Geological history

Theories of formation

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Whiffs in the air

A transition, pinned

Getting a “decent hold”

Formation and history

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Map

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Discovery

Description

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Map

Radioactive material tells time

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Megalithic mind frame

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Map

Fire the “laser”

Here’s how they figured it out:

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