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Satellites peer into rock 50 miles beneath Tibetan Plateau

Topography (left) and a shaded relief map (right) of the rock deep beneath the Tibetan Plateau. Color indicates kilometers below Earth’s surface. Credit: Image by Younghong Shin of the Korea Institute of Geosciences and Mineral Resource, courtesy of The Ohio State University.

Gravity data captured by satellite has allowed researchers to take a closer look at the geology deep beneath the Tibetan Plateau.

The analysis, published in the journal Nature Scientific Reports, offers some of the clearest views ever obtained of rock moving up to 50 miles below the plateau, in the lowest layer of Earth’s crust.

There, the Indian tectonic plate presses continually northward into the Eurasian tectonic plate, giving rise to the highest mountains on Earth — and deadly earthquakes, such as the one that killed more than 9,000 people in Nepal earlier this year.

The study supports what researchers have long suspected: Horizontal compression between the two continental plates is the dominant driver of geophysical processes in the region, said C.K. Shum, professor and Distinguished University Scholar in the Division of Geodetic Science, School of Earth Sciences at The Ohio State University and a co-author of the study.

“The new gravity data onboard the joint NASA-German Aerospace Center GRACE gravimeter mission and the European Space Agency’s GOCE gravity gradiometer mission enabled scientists to build global gravity field models with unprecedented accuracy and resolution, which improved our understanding of the crustal structure,” Shum said. “Specifically, we’re now able to better quantify the thickening and buckling of the crust beneath the Tibetan Plateau.”

Shum is part of an international research team led by Younghong Shin of the Korea Institute of Geosciences and Mineral Resource. With other researchers in Korea, Italy and China, they are working together to conduct geophysical interpretations of the Tibetan Plateau geodynamics using the latest combined gravity measurements by the GOCE gravity gradiometer and the GRACE gravimeter missions.

Satellites such as GRACE and GOCE measure small changes in the force of gravity around the planet. Gravity varies slightly from place to place in part because of an uneven distribution of rock in Earth’s interior.

The resulting computer model offers a 3-D reconstruction of what’s happening deep within earth.

As the two continental plates press together horizontally, the crust piles up. Like traffic backing up on a congested freeway system, the rock follows whatever side roads may be available to relieve the pressure.

But unlike cars on a freeway, the rock beneath Tibet has two additional options for escape. It can push upward to form the Himalayan mountain chain, or downward to form the base of the Tibetan Plateau.

The process takes millions of years, but caught in the 3-D image of the computer model, the up-and-down and side-to-side motions create a complex interplay of wavy patterns at the boundary between the crust and the mantle, known to researchers as the Mohorovičić discontinuity, or “Moho.”

“What’s particularly useful about the new gravity model is that it reveals the Moho topography is not random, but rather has a semi-regular pattern of ranges and folds, and agrees with the ongoing tectonic collision and current crustal movement measured by GPS,” Shin said.

As such, the researchers hope that the model will provide new insights into the analysis of collisional boundaries around the world.

Co-author Carla Braitenberg of the University of Trieste said that the study has already helped explain one curious aspect of the region’s geology: the sideways motion of the Tibetan Plateau. While India is pushing the plateau northward, GPS measurements show that portions of the crust are flowing eastward and even turning to the southeast.

“The GOCE data show that the movement recorded at the surface has a deep counterpart at the base of the crust,” Braitenberg said. Connecting the rock flow below to movement above will help researchers better understand the forces at work in the region.

Those same forces led to the deadly Nepal earthquake in April 2015. But Shum said that the new model almost certainly won’t help with earthquake forecasting — at least not in the near future.

“I would say that we would understand the mechanism more if we had more measurements,” he said, but such capabilities “would be very far away.”

Even in California — where, Shum pointed out, different tectonic processes are at work than in Tibet — researchers are unable to forecast earthquakes, despite having abundant GPS, seismic and gravity data. Even less is known about Tibet, in part because the rough terrain makes installing GPS equipment difficult.

Other co-authors on the study included Sang Mook Lee of Seoul National University; Sung-Ho Na of the University of Science and Technology in Daejeon, Korea; Kwang Sun Choi of Pusan National University; Houtse Hsu of the Institute of Geodesy & Geophysics, Chinese Academy of Sciences; and Young-Sue Park and Mutaek Lim of the Korea Institute of Geosciences and Mineral Resource.

This research was supported by the Basic Research Project of the Korea Institute of Geoscience and Mineral Resources, funded by the Ministry of Science, ICT and Future Planning of Korea. Shum was partially supported by NASA’s GRACE Science Team Program and Concept in Advanced Geodesy Program. Braitenberg was partially supported by the European Space Agency’s Center for Earth Observation as part of the GOCE User ToolBox project.

Reference:
Young Hong Shin, C.K. Shum, Carla Braitenberg, Sang Mook Lee, Sung -Ho Na, Kwang Sun Choi, Houtse Hsu, Young-Sue Park, Mutaek Lim. Moho topography, ranges and folds of Tibet by analysis of global gravity models and GOCE data. Scientific Reports, 2015; 5: 11681 DOI: 10.1038/srep11681

Note: The above post is reprinted from materials provided by Ohio State University. The original item was written by Pam Frost Gorder.

Genome analysis pins down arrival and spread of first Americans

The migration route of Siberians into North America and the subsequent split into northern and southern Amerindian populations. Analysis of current and ancient genomes shows that there also was some later interbreeding between East Asians and Inuit.

The original Americans came from Siberia in a single wave no more than 23,000 years ago, at the height of the last Ice Age, and apparently hung out in the north — perhaps for thousands of years — before spreading in two distinct populations throughout North and South America, according to a new genomic analysis.The findings, which will be reported in the July 24 issue of Science, confirm the most popular theory of the peopling of the Americas, but throws cold water on others, including the notion of an earlier wave of people from East Asia prior to the last glacial maximum, and the idea that multiple independent waves produced the major subgroups of Native Americans we see today, as opposed to diversification in the Americas.

This Ice Age migration over a land bridge between Siberia and Alaska is distinct from the arrival of the Inuit and Eskimo, who were latecomers, spreading throughout the Artic beginning about 5,500 years ago.

The findings also dispel the idea that Polynesians or Europeans contributed to the genetic heritage of Native Americans.

The analysis, using the most comprehensive genetic data set from Native Americans to date, was conducted using three different statistical models, two of them created by UC Berkeley researchers. The first, developed by the lab of Yun Song, a UC Berkeley associate professor of statistics and of electrical engineering and computer sciences, takes into account the full DNA information available from the genomes in the study. A second method, developed by Rasmus Nielsen, a UC Berkeley professor of integrative biology, and graduate student Kelley Harris, requires much less computation, but relies on a summary of the genome data. These and a third method developed by researchers at the Wellcome Trust Sanger Institute, England, all yielded consistent results. Song and Nielsen are two of three corresponding authors of the paper.

Modern and ancient genomes

The data consisted of the sequenced genomes of 31 living Native Americans, Siberians and people from around the Pacific Ocean, and the genomes of 23 ancient individuals from North and South America, spanning a time between 200 and 6,000 years ago.

“There is some uncertainty in the dates of the migration and the divergence between the norther and southern Amerindian populations,” Song noted, “but as we get more ancient genomes sequenced, we will be able to put more precise dates on the times of migration.”

The international team concluded that the northern and southern Native American populations diverged between 11,500 and 14,500 years ago, with the northern branch leading to the present day Athabascans and Amerindians broadly distributed throughout North America. The southern branch peopled Central and South America, as well as part of northern North America.

“The diversification of modern Native Americans appears to have started around 13,000 years ago when the first unique Native American culture appears in the archeological record: the Clovis culture,” said Nielsen. “We can date this split so precisely in part because we previously have analyzed the 12,600-year-old remains of a boy associated with the Clovis culture.”

One surprise in the genetic data is that both populations of Native Americans have a small admixture of genes from East Asians and Australo-Melanesians, including Papuans, Solomon Islanders and Southeast Asian hunter gatherers.

“It’s a surprising finding and it implies that New World populations were not completely isolated from the Old World after their initial migration,” said Eske Willerslev from the Centre for GeoGenetics at the Natural History Museum, University of Copenhagen, who headed the study. “We cannot say exactly how and when this gene flow happened, but one possibility is that it came through the Aleutian Islanders living off the coast of Alaska.”

Song added that the state-of-the-art statistical methods that his and Nielsen’s labs developed “are being made publicly available so that they can be used by others to study complex demographic histories of other populations.

Reference:
Maanasa Raghavan at al. Genomic evidence for the Pleistocene and recent population history of Native Americans. Science, 2015 DOI: 10.1126/science.aab3884

Note: The above post is reprinted from materials provided by University of California – Berkeley. The original item was written by Robert Sanders.

Ancient life in three dimensions

An infant marine crocodile, Pelagosaurus typus, (BRLSI.M1418), just 23 cm long. Many of the marine reptiles from Strawberry Bank are juveniles. Credit: © Bath Royal Literary and Scientific Institution

Hidden secrets about life in Somerset 190 million years ago have been revealed by researchers at the University of Bristol and the Bath Royal Literary and Scientific Institution (BRLSI) in a new study of some remarkable fossils. Thanks to exceptional conditions of preservation, a whole marine ecosystem has been uncovered — and yet it was already known 150 years ago.

The fossils come from Strawberry Bank in Ilminster, Somerset, but the site has now been lost, having been built over. They were discovered by noted Bath-based geologist Charles Moore (1815-1881), who first spotted them when he saw some school boys kicking a rounded boulder about. He cracked it open, and to his amazement, a perfect three-dimensionally preserved fish lay inside. After this first find, Moore collected hundreds more nodules, and the entire collection has lain, almost forgotten, in the museum of the BRLSI in Queen’s Square, Bath ever since.

Matt Williams, curator of the collection, said: “It was obvious that these fossils where very special from the first time I saw them on joining the BRLSI. Our stores are full of treasures, but these specimens are truly unique. We secured some funding to clean up the specimens, and curate them, and we even uncovered some unexpected treasures.”

Collaborator Professor Michael Benton from Bristol’s School of Earth Sciences, said: “When Matt first showed me the fossils I couldn’t believe it. There are 100 nodules containing a large fish called Pachycormus, five or six tiny marine crocodiles, and two species of ichthyosaurs. There are also early squid with their ink sacs and other soft tissues preserved, and hundreds of insects that had flown out over the shallow, warm seas of the day.”

Work will now begin in earnest on the fossils, thanks to a £250,000 grant from the Leverhulme Trust which will allow for three-dimensional scanning to be carried out and also fund young researchers to work in Bristol and Oxford with fossil fish expert, Dr Matt Friedman.

A review of the fossils is published today in the premier British geological journal, Journal of the Geological Society.

Reference:
Matt Williams, Michael J. Benton, Andrew Ross. The Strawberry Bank Lagerstätte reveals insights into Early Jurassic life. Journal of the Geological Society, 2015; 2014-144 DOI: 10.1144/jgs2014-144

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

Surfer 13

Surfer is a full-function 3D visualization, contouring and surface modeling package that runs under Microsoft Windows. Surfer is used extensively for terrain modeling, bathymetric modeling, landscape visualization, surface analysis, contour mapping, watershed and 3D surface mapping, gridding, volumetrics, and much more.

What’s New in Surfer 13?

We have compiled a list of some of the top new features in Surfer 13. This list is only a small sampling of the new features added to Surfer 13.

  • Graticule and Grid
  • Viewshed Maps
  • More Geoprocessing Tools
  • Query Base Map Objects
  • Attribute Management
  • Utilize the New Welcome Dialog
  • Display Lat/Lon Labels In DMS Format
  • Create Image Maps with Hill Shading
  • Add a Title to Your Color Scale Bar
  • Display Labels in Custom Date/Time Format
  • Improved WMS Connectivity
  • Specify Units for Local Coordinate Systems
  • Limit the Z Range of Gridded Data
  • SID and ECW Import Improvements
  • Calculate Statistics on Range of Values
  • Changing Blanking Flag when Saving Digitized Data
  • Consecutively Delete Vertices when Reshaping
  • Assign Coordinate System to All Unreferenced Layers
  • Search for Coordinate Systems
  • New Coordinate Systems and Datums
  • New and Improved Import Functions
  • New and Improved Export Functions
  • New Automation Commands

More about What’s New in Surfer 13? Click Here

Features

Surfer’s sophisticated interpolation engine transforms your XYZ data into publication-quality maps. Surfer provides more gridding methods and more control over gridding parameters, including customized variograms, than any other software package on the market. You can also use grid files obtained from other sources, such as USGS DEM files or ESRI grid files. Display your grid as outstanding contour, 3D surface, 3D wireframe, watershed, vector, image, shaded relief, and viewshed maps. Add base maps to show boundaries and imagery, post maps to show point locations, and combine map types to create the most informative display possible. Virtually all aspects of your maps can be customized to produce exactly the presentation you want. Generating publication quality maps has never been quicker or easier.

Create colorful contour maps with custom levels, colors, and a color scale!

Contour Maps

Display contour maps over any contour range and contour interval, or specify only the contour levels you want to display on the map. And with Surfer you can add color fill between contours to produce dazzling displays of your maps, or produce gray scale fills for dramatic black and white printouts.
More Info.

Create exciting 3D surface maps from your XYZ data! Image courtesy of Igor Yashayaev, Bedford Institute of Oceanography, Fisheries and Oceans, Canada

3D Surface Maps

The 3D surface map uses shading and color to emphasize your data features. Change the lighting, display angle and tilt with a click of the mouse. Overlay several surface maps to generate informative block diagrams.
More Info.

Image Maps

.Surfer image maps use different colors to represent Z values of a grid file. Surfer optionally blends colors between Z values so you end up with a smooth color gradation over the entire map, or you can leave the colors unblended so each cell in the grid file shows a distinct color. Choose to display the image map with hill shading to give a 3D effect.

This powerful feature allows you to create color maps using any combination of colors. Add a color scale to show the values of the different colors! Image maps can be created independently of other maps, or can be combined with other map layers. They can be scaled, resized, limited and moved.
More Info.

Post Maps

Post maps show points at XY locations, such as sample locations, well locations, or original data point locations. Use the points to show the distribution of data points on the map, and to demonstrate the accuracy of the gridding methods you use. Add multiple labels to the points, connect the points with a line, and control the size, shape and color of the symbol.

Also create classed post maps that identify different ranges of data by automatically assigning a different symbol or color to each data range.
More Info.

Base Maps

Display your base maps in Surfer alone or overlay them on other maps.

Surfer can import maps in many different formats to display geographic information. Base maps are created from any number of file formats, such as SHP, DXF, GeoTIFF, and PDF. In addition to loading existing files as base map, you can also download georeferenced imagery automatically from countless free online Web Map Service (WMS) servers through Surfer’s built-in WMS browser. Connect to the online data source, pick the layer of interest you want to download, and then watch as Surfer downloads the image and seamlessly loads it into your project.

Combine base maps with other map layers in map overlays, or create stand-alone base maps independent of other maps on the page. Load any number of base maps on a page. It is easy to overlay a base map on a contour or surface wireframe map, allowing you to display geographic information in combination with the three dimensional data.

When using base map data with attribute information (such as the data in SHP files), you can manage the attribute data easily in the attribute table and query objects based on object property or attribute information.
More Info.

Shaded Relief Maps

Create spectacular maps in seconds.

Shaded relief maps are raster images based on grid files. Colors are assigned based on slope orientation relative to a light source. Surfer determines the orientation of each grid cell and calculates reflectance of a point light source on the grid surface.

The light source can be thought of as the sun shining on a topographic surface. Surfer automatically blends colors between percentage values so you end up with a smooth color gradation over the map. You can add color anchors so each anchor point can be assigned a unique color, and the colors are automatically blended between adjacent anchor points. This allows you to create color maps using any combination of colors. Shaded relief maps can be created independently of other maps, or can be combined with other layers. Shaded relief maps can be scaled, resized, limited, and moved in the same way as other types of maps.
More Info.

A USGS SDTS DEM file was used to create this map and color zones were defined for the X and Y lines.

3D Wireframe Maps

Surfer wireframe maps provide an impressive three dimensional display of your data. Wireframes are created by connecting Z values along lines of constant X and Y.
More Info.

Vector Maps

Instantly create vector maps in Surfer to show direction and magnitude of data at points on a map. You can create vector maps from information in one grid or two separate grids. The two components of the vector map, direction and magnitude, are automatically generated from a single grid by computing the gradient of the represented surface.

At any given grid node, the direction of the arrow points in the direction of the steepest descent. The magnitude of the arrow changes depending on the steepness of the descent. Two-grid vector maps use two separate grid files to determine the vector direction and magnitude. The grids can contain Cartesian or polar data. With Cartesian data, one grid consists of X component data and the other grid consists of Y component data. With polar data, one grid consists of angle information and the other grid contains length information. Overlay vector maps on contour or wireframe maps to enhance the presentation!
More Info.

Watershed Maps

Detail every aspect of your map from creating watershed boundaries to adding city streets and surrounding elevations, like the above map of Seward, Alaska.

Watershed maps automatically calculate and display drainage basins and streams from your grid file.

Create colorful watershed maps to display regions draining into a stream, stream system or body of water. Display the catchment basins, streams, or both. Export the basins and streams to any supported file format, including SHP and DXF files, for use in other software! Surfer uses the accurate eight-direction pour point algorithm to calculate the flow direction at each grid node.
More Info.

Viewshed Maps

.Perform viewshed analysis using a loaded grid file with a user-specified transmitter location, height, starting angle and radius. All visible areas from the transmitter location within the selected radius are filled with a user-specified color. Alternatively, choose to display the invisible areas from the transmitter.

Viewshed analysis is useful in many applications, such as determining if mining operations or drill rigs can be viewed from public locations, determining what is visible from trails or roads, and to locate communication towers.
More Info.

Profiles

Surfer’s automatic profile tool makes it easy to visualize the change in Z value from one point to another.

Simply select the map, add a profile, and draw the line on the map. Include as many points as you want in the line; it could be a simple two-point line, or a zig-zag shape. In all cases, the profile is created showing the Z value change along the length of the line. Reshape the line on the map, and the profile automatically updates.
More Info.

Graticule and Grid Lines

Add graticule lines or another grid to your map to view the location in multiple sets of coordinate units!  Display latitude and longitude graticule lines over a projected map, or create a map in meters and add a grid in feet.
More Info.

More Features

System Requirements

  • Windows XP SP2 or higher, Vista, 7, 8 (excluding RT) or higher
  • 32-bit and 64-bit operating systems supported
  • 1024 x 768 or higher monitor resolution with 16-bit (or higher) color depth
  • At least 500 MB free hard disk space
  • At least 512 MB RAM minimum
32-bit and 64-bit versions of Surfer are available.

Overview Video

This video is an introduction to the updated user-interface of Surfer 13.

Free Demo Downloads

Copyright © 2015 Golden Software, LLC. All rights reserved.

Antarctic offers insights into life on Mars

Operation IceBridge project scientist Michael Studinger took the photo of Taylor Valley,, one of the Dry Valleys of Antarctica where snow and ice are rare. Credit: NASA

The cold permafrost of Antarctica houses bacteria that thrive at temperatures below freezing, where water is icy and nutrients are few and far between. Oligotrophs, slow-growing organisms that prefer environments where nutrients are scarce, could provide clues as to how life could exist in the permafrost of Mars.

“The slow-growing lifestyle of oligotrophs is clearly beneficial in the environment as these oligotrophs often dominate the communities in which they are found,” Corien Bakermans, assistant professor of microbiology at Penn State Altoona, told Astrobiology Magazine by email.

Bakermans was the principal investigator of a group of scientists who studied the lethargic bacteria from the Dry Valleys of Antarctica, a row of snow-free valleys that represents one of Earth’s most extreme desert environments.

“In cold, low-nutrient environments, slow growth is the law, and there are fewer fast-acting processes that disrupt that slow growth,” Bakermans said.

Thriving in Taylor Valley

Permafrost is ground that remains at or below 0° C (32° F) for at least two consecutive years. The permafrost of Antarctica’s Dry Valleys house a small supply of bacteria, but the remote location makes sampling them a challenge. While permafrost exists in the more accessible Arctic regions, the Antarctic permafrost contains a higher organic count, although isn’t as well studied, Bakermans said.

Bakermans examined Taylor Valley, the southernmost of the three main valleys that make up the McMurdo Dry Valleys. Rather than focusing on the microbes that lie on the surface, her team chose to delve into the permafrost.

After setting up a clean room over the site, Bakermans’ team dug a pit roughly 20 inches (50 centimeters) square, using organic-free sterile stainless steel tools to avoid contaminating the site. They collected samples of the permafrost from a range of depths and transported them to another site where they could more easily study the microbes.

The samples they found were dominated by the phyla Acidobacteria and Gemmatimonadetes, bacteria that have not been seen in other Antarctic permafrost samples, Bakermans said. The two phyla—the second largest taxonomic rank, after kingdom—were identified as recently as 1997 and 2003, respectively.

“While these bacterial phyla are abundant in many environments, not much is known about them, given that they were only recently identified, and very few species have been successfully cultured, or grown in the lab,” said Bakermans.

Finding them in Taylor Valley wasn’t completely surprising, however.

“Many species from these phyla appear to be adapted to low-nutrient and low-water conditions, which are common in Taylor Valley,” Bakermans said. “This likely contributed to the dominance of these phyla in Taylor Valley permafrost.”

Scientists can study the genetic makeup of bacteria to track their relationships among various species. The team extracted two specific genes from bacteria in the permafrost and placed them into clones to characterize the challenging bacteria.

“All bacteria contain at least one copy of each of these genes, but very often we cannot grow these bacteria in the lab to examine them,” Bakermans said.

“By transferring the genes from the permafrost bacterium to the clone, which can be grown in the laboratory, we can now examine the genes.”

By changing the environment and monitoring production of carbon dioxide—the respiration of the organisms—the scientists were able to understand how various environments affected the bacteria. Samples were started at very low temperatures of -20° C (-4° F) and then incubated at a variety of higher temperatures to determine where they thrived. They found that activity occurred as low as -5° C (23° F) and peaked at 15° C (59° F).

The research was published in the journal FEMS Microbiology Ecology and was funded by the NASA Astrobiology Science and Technology for Exploring Planets program.

‘How life survives’

The Dry Valleys of Antarctica serve as a proving ground for how life can endure in inhospitable environments, such as the arid regions of Mars. The valleys are cold and dry, though they don’t reach Martian extremes, where the temperatures average about -80° F (-60° C). Their permafrost is similar to the permafrost and ground ice found in the middle to high latitudes of Mars.

While evolution on other planets may not follow the exact same track, studying bacteria that survive and thrive in the most inhospitable regions on Earth can provide some insight into what it might take for alien organisms to endure elsewhere.

“These valleys are important for understanding how life survives in extreme cold and dry,” astrobiologist Chris McKay of NASA Ames Research Center told Astrobiology Magazine by email.

McKay was one of the co-authors on Bakermans’ study. He specializes in valleys drier and higher than Taylor Valley in permafrost that contains less liquid, making it compositionally more similar to Martian soil, where only ice and vapor form rather than liquid water.

Low in humidity, the Dry Valleys don’t have a lot of water, the ingredient required for life as we know it. Despite their Antarctic locale, the valleys lack snow and ice, forming the largest ice-free region on the continent.

The Dry Valleys can serve as a window into finding evidence for past life on Mars, as scientists scouring the regions find traces of previous generations as well as thriving organisms.

“They help us understand how evidence for life in the form of dead microorganisms is preserved under these conditions,” McKay said.

Note: The above post is reprinted from materials provided by Astrobio.net.
This story is republished courtesy of NASA’s Astrobiology Magazine. Explore the Earth and beyond at www.astrobio.net .

Finding the origins of life in a drying puddle

Georgia Tech postdoctoral fellow Jay Forsythe loads a sample into a mass spectrometer. The testing was done to see what compounds were formed by subjecting mixtures of amino and hydroxy acids to repeated wet-dry cycles. Credit: John Toon, Georgia Tech

Anyone who’s ever noticed a water puddle drying in the sun has seen an environment that may have driven the type of chemical reactions that scientists believe were critical to the formation of life on the early Earth.

Research reported July 15 in the journal Angewandte Chemie International Edition demonstrates that important molecules of contemporary life, known as polypeptides, can be formed simply by mixing amino and hydroxy acids – which are believed to have existed together on the early Earth – then subjecting them to cycles of wet and dry conditions. This simple process, which could have taken place in a puddle drying out in the sun and then reforming with the next rain, works because chemical bonds formed by one compound make bonds easier to form with the other.

The research supports the theory that life could have begun on dry land, perhaps even in the desert, where cycles of nighttime cooling and dew formation are followed by daytime heating and evaporation. Just 20 of these day-night, wet-dry cycles were needed to form a complex mixture of polypeptides in the lab. The process also allowed the breakdown and reassembly of the organic materials to form random sequences that could have led to the formation of the polypeptide chains that were needed for life.

“The simplicity of using hydration-dehydration cycles to drive the kind of chemistry you need for life is really appealing,” said Nicholas Hud, a professor in the School of Chemistry and Biochemistry at the Georgia Institute of Technology, and director of the NSF Center for Chemical Evolution, which is also supported by the NASA Astrobiology Program. “It looks like dry land would have provided a very favorable environment for getting the chemistry necessary for life started.”

Origin-of-life scientists had previously made polypeptides from amino acids by heating them well past the boiling point of water, or by driving polymerization with activating chemicals. But the high temperatures are beyond the point at which most life could survive, and the robust availability of activating chemicals on the early Earth is questionable. The simplicity of the wet-dry cycle therefore makes it attractive to explain how peptides could have formed, Hud added.

The idea for combining chemically similar amino acids and hydroxyl acids was inspired by the demonstration that polyesters are easy to form by repetitive hydration-dehydration cycles and the fact that esters are activated to attack by the amino group of amino acids. The potential importance of this reaction in the earliest stages of life is supported by studies of meteorites, which revealed that both compounds would have been present on the prebiotic Earth.

Hydroxy acids combine to form polyester, better known as a synthetic textile fiber, and that reaction requires less energy than formation of the amide bonds needed to create peptides from amino acids. In the wet-dry cycles, formation of polyester comes first – which then facilitates the more difficult peptide formation, Hud said.

“The ester linkages that we are making in the polyester can serve as an activating agent formed within the solution,” he explained. “Over the course of a very simple chemical evolution, the polymers progress from having hydroxy acids with ester linkages to amino acids with peptide linkages. The hydroxy acids are gradually replaced through the wet and dry cycles because the ester bonds holding them together are not as stable as the peptide bonds.”

Experimentally, graduate student Sheng-Sheng Yu put the amino and hydroxy acid mixtures through 20 wet-dry cycles to produce molecules that are a mixture of polyesters and peptides, containing as many as 14 units. After just three cycles, and at temperatures as low as 65 degrees Celsius, peptides consisting of two and three units began to form. Postdoctoral fellow Jay Forsythe confirmed the chemical structures using NMR mass spectrometry.

“We allowed the peptide bonds to form because the ester bonds lowered the energy barrier that needed to be crossed,” Hud added.

On the early Earth, those cycles could have taken 20 days and nights – or perhaps much longer if the heating and drying cycles corresponded to seasons of the year.

Beyond easily forming the polypeptides, the wet-dry process has an additional advantage. It allows compounds like peptides to be regularly broken apart and reformed, creating new structures with randomly-ordered amino acids. This ability to recycle the amino acids not only conserves organic material that may have been in short supply on the early Earth, but also provides the potential for creating more useful combinations.

A combination of hydroxy and amino acids likely existed in the prebiotic soup of the early Earth, but analyzing such a “messy” reaction was challenging, Hud said. “We were led into this idea that a mixture might work better than separate components,” he explained. “It might have been messy at the start, but it’s easier to get going than a pristine chemical reaction.”

Beyond helping explain how life might have started, the wet-dry cycles could also provide a new way to synthesize polypeptides. Existing techniques produce the chemicals through genetic engineering of microorganisms, or through synthetic organic chemistry. The wet-dry cycling could provide a simpler and more sustainable water-based process for producing these chemicals.

The demonstration of peptide formation opens the door to asking other questions about how life may have gotten going in prebiotic times, said Ramanarayanan Krishnamurthy, a member of the research team and an associate professor of chemistry at the Scripps Research Institute. Future studies will include a look at the sequences formed, whether there are sequences favored by the process, and what sequences might result. The process could ultimately lead to reactions able to continue without the wet-dry cycles.

“If this process were repeated many times, you could grow up a peptide that could acquire a catalytic property because it had reached a certain size and could fold in a certain way,” Krishnamurthy said. “The system could begin to develop certain emergent characteristics and properties that might allow it to self-propagate.”

Video

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

The planetary sweet spot

Of the more than 1,000 verified planets found by NASA’s Kepler Space Telescope, eight are less than twice Earth-size and in their stars’ habitable zone. Credit: NASA 

Planet Earth is situated in what astronomers call the Goldilocks Zone — a sweet spot in a solar system where a planet’s surface temperature is neither too hot nor too cold. An ideal distance from a home star — in Earth’s case, the sun – this habitable zone, as it is also known, creates optimal conditions that prevent water from freezing and generating a global icehouse or evaporating into space and creating a runaway greenhouse.

However, a new theory by UC Santa Barbara geochemist Matthew Jackson posits that the bulk composition of a planet may also play a critical role in determining the planet’s tectonic and climatic regimes and therefore its habitability. In a paper published today in Nature Geoscience, Jackson, an associate professor in UCSB’s Department of Earth Science, and Mark Jellinek of the University of British Columbia discuss their research.

According to Jackson, plate tectonics is a manifestation of the Earth trying to cool itself. Cold plates sink into the Earth and absorb heat, while volcanoes release heat where plates are spreading apart and forming. “Whether or not plate tectonics can happen actually depends on whether or not the Earth is too hot or too cold,” he said. “If it’s too hot, plate tectonics seizes up and if it’s too cold, it freezes up.”

Until a decade ago, Jackson noted, scientists based the Earth’s composition on a model tied to ancient stony meteorites called chondrites, which were considered the building blocks of the planet. Then studies analyzing the ratio of two neodymium isotopes — 142Nd and 144Nd — demonstrated that Earth’s composition may differ from that of chondrites — and differ enough to send scientists back to the drawing board.

In 2013, Jackson and Jellinek published a new compositional model of the Earth in which a large portion of the mantle was depleted to form the continental crust. The model also assumed a 30 percent reduction in the uranium, thorium and potassium content in the planet. The decay of these naturally occurring elements generates almost all of the planet’s radioactive heat.

The new paper takes this revised model further by examining Earth’s geodynamics. “We argue that if the planet had as much uranium, thorium and potassium as the old model, plate tectonics might not be possible,” explained Jackson. “If this is the case, you can end up with a planet that has only one big plate and can become an extreme greenhouse like Venus. The new compositional model gives Earth a sweet spot of its own where its interior is neither too hot nor too cold — a place that allows our current mode of plate tectonics to operate.”

Jackson added that the thermal and tectonic histories of the Earth are intimately intertwined, and this latest paper explores what happens if heat production is turned down by a third, as the new compositional model suggests.

If uranium, thorium and potassium govern whether or not plate tectonics can occur, as Jackson and Jellinek propose, astronomers looking for habitable planets might have another parameter to consider. Since NASA’s Kepler Space Telescope has already found more than 1,000 planets — a small fraction of which reside in the habitable zone around their respective stars — it is important to understand how additional variables, including a planet’s composition, can narrow the field of potentially habitable extrasolar worlds.

“Our hypothesis suggests that among the rocky exoplanets, there’s another dial that’s important to turn when considering whether a planet is habitable or not: its bulk composition,” Jackson said. “Bulk composition determines its uranium, thorium and potassium abundance, which governs its internal radiogenic heating and ultimately dictates whether or not plate tectonics can happen — as well as the amount of volcanism and the release of CO2 from a planet that can occur. These are the variables that determine whether a planet can support a habitable climate.”

Note: The above post is reprinted from materials provided by University of California – Santa Barbara.

Living Rock: An Introduction to Earth’s Geology

Living Rock – An Introduction to Earth’s Geology movie was released Aug 13, 2002 by the DVD International studio. Ever wonder why earthquakes happen, or how a volcano works? Living Rock – An Introduction to Earth’s Geology movie Find the answers to these and many other questions in LIVING ROCK, a fun and educational program about the Earth’s geology, jointly produced by the US Geological Survey and Alpha DVD.

Living Rock – An Introduction to Earth’s Geology video Introduces concepts such as Geologic Time, Continental Crust, Plate Tectonics, Volcanic Activity, Earthquakes, Subduction Zones, Erosion, and Glaciers.

Five bizarre fossil discoveries that got scientists excited

A seminal discovery. Credit: Department of Palaeobiology, Swedish Museum of Natural History

From trilobites to tyrannosaurs, most fossils are of creatures with hard shells or bones. These materials don’t easily biodegrade and sediment has time to build up around them and turn them into a record of the creature that is still with us millions of years after it has died. Soft-bodied organisms like worms, on the other hand, decay rapidly and their fossil record is decidedly patchy.

In exceptional circumstances, however, their remains are preserved and sometimes in the most unusual places. With the right detective skills, palaeontologists can use such discoveries to open up whole new windows on the history of life on Earth. A recent discovery found in 50-million-year-old rocks from Antarctica has yielded a particularly incredible example: fossilised worm sperm.

It’s a great reminder that there are far stranger fossils out there than dinosaur bones. Here are some of the most bizarre specimens ever found.

1. Ancient sperm

A seminal discovery. Credit: Department of Palaeobiology, Swedish Museum of Natural History

This remarkable find of fossilised spermatozoa from a clitellate or “collared” worm represents the oldest animal sperm ever discovered, beating the previous record holder – springtail sperm found in Baltic amber – by at least ten million years.

The sperm preservation was made possible because such worms reproduce by releasing their eggs and sperm into protective cocoons. In this case, a tough shell kept the cocoons intact until scientists discovered them in shallow marine gravels on the Antarctic Peninsula. Even then, it required high-powered microscopic analysis for the sperm to be spotted.

The sperm most resemble those of a leech-like group of worms that attach themselves to crayfish, even though today these live only in the northern hemisphere. But the researchers think the technique could be applied to other cocoon fossils, and help us learn more about previously cryptic creatures.

2. A well-endowed Silurian shrimp

If 50-million-year-old spermatozoa are surprising, what about a 425-million-year-old penis? Discovered in a ditch near the Anglo-Welsh border in the early 2000s, a tiny ostracod, or seed shrimp, proved to be quite clearly male. Preserved in three-dimensions with all its soft tissues fossilised, it was proportionally well-endowed. “Old Todger” was the headline in the The Sun newspaper.

During the Silurian period (443-419 million years ago), the Welsh borderlands lay on the shelf of a tropical sea. Marine animals were occasionally smothered, entombed and petrified by the ash of distant volcanoes. The ostracod – and countless other small fossils – cannot be seen adequately using microscopes, however, so their mineral tomb has to be gradually ground away and the fossil recreated with 3D digital imaging.

3. Ancient reptile poo and puke

Credit: Poozeum/Wikimedia Commons, CC BY-SA

The notion that where there’s muck there’s brass is perhaps best shown by coprolites: petrified dung that can be found in many palaeontological shops. Beyond the novelty, such specimens are “trace fossils” of tremendous palaeoecological value. This means they can tell scientists precisely what an extinct creature was eating.

Coprolites are actually just one element of a richer broth, that of bromalites or “stink rocks”. The term was coined in the early 1990s to encompass all matter of excreta preserved in the rock record, and in the last few years, bromalites have been popping up everywhere.

In Australia, they show that Cretaceous plesiosaurs were bottom feeders. In Poland the regurgitated dinners of shell-crushing fish help us work out how life recovered from the biggest mass extinction in Earth history. And in Jurassic shales from Peterborough and Whitby, pavements of squid-like belemnites have been interpreted as ichthyosaur vomit.

4. Yorkshire rhinos

Buckland in the hyaena’s cave

One very odd fossil discovery was made in Kirkdale Cave, near Kirkbymoorside, North Yorkshire in 1821. Workman quarrying for roadstone found a cliffside hollow full of large animal bones. They were at first thought to be cattle, but a local naturalist saw that they were more exotic-looking, and the remains eventually made their way to Oxford University’s Professor William Buckland.

A man who claimed to have eaten his way through the entire animal kingdom, Buckland was the most marvellous experimental scientist. He recognised that the bones were mainly of large herbivores, such as elephants and rhinos. They showed signs of having been gnawed, and fossilised faeces found on the cave floor resembled those of hyaenas. Conveniently being in possession of one as a pet, Buckland proved Kirkdale Cave had been a hyaena den, and founded the science of palaeoecology. Almost two hundred years on, we know that “African” megafauna roamed the Vale of Pickering about 125,000 years ago, in a warm phase between ice ages.

5. A mystery monster

Credit: Ghedoghedo/Wikimedia Commons, CC BY-SA

The fossils of Mazon Creek in Illinois, USA, were first encountered during coal mining in the 19th Century. But it wasn’t until the 1950s that the site became fossiliferously famous, thanks to Francis Tully’s discovery of an exceptionally weird beast: a beautifully preserved soft-bodied animal revealed in a naturally split mineral nodule.

Specimens turned out to be quite abundant but unique to Mazon Creek, and the beast was given the name of Tullimonstrum gregarium. It is now the state fossil of Illinois. Trouble is, no-one knows what Mr Tully’s Common Monster really is. A few inches long, it has a long snout with toothy pincers at the end, two eyes on stalks, a segmented body, and a finned tail. It was probably a predator, and the rocks it was found in suggest that it lived in tropical, shallow seas.

Beyond that, after more than half a century, we’re not much the wiser. It cannot be satisfactorily united with any other invertebrate group, living or extinct. Even with exceptional preservation, the fossil record always has the capacity to surprise.

Note: The above post is reprinted from materials provided by The Conversation.
This story is published courtesy of The Conversation (under Creative Commons-Attribution/No derivatives).The Conversation

Carbon dioxide pools discovered in Aegean Sea

Topographic relief map of the northern Santorini volcanic field. The white star icon shows the location of the Kallisti Limnes CO2 pools. The onshore Kolumbo fault is indicated by a dashed red line, which along with the Kolumbo line, describes the northeast portion of the Christianna-Santorini-Kolumbo (CSK) tectonic line. The inset box shows a detailed view from the southwest of the caldera slope bathymetry around the study site; submersible vehicle track lines are indicated as red, orange, and yellow lines, corresponding to the first and second AUV dives, and the HOV dive, respectively. Credit: Illustration courtesy of Camilli, et al 

The location of the second largest volcanic eruption in human history, the waters off Greece’s Santorini are the site of newly discovered opalescent pools forming at 250 meters depth. The interconnected series of meandering, iridescent white pools contain high concentrations of carbon dioxide (CO2) and may hold answers to questions related to deepsea carbon storage as well as provide a means of monitoring the volcano for future eruptions.

“The volcanic eruption at Santorini in 1600 B.C. wiped out the Minoan civilization living along the Aegean Sea,” said Woods Hole Oceanographic Institution (WHOI) scientist Rich Camilli, lead author of a new study published today in the journal Scientific Reports. “Now these never-before-seen pools in the volcano’s crater may help our civilization answer important questions about how carbon dioxide behaves in the ocean.”

Camilli and his colleagues from the University of Girona, National and Kapodistrian University of Athens, Institut de Physique du Globe de Paris, and Hellenic Centre for Marine Research (HCMR), working in the region in July 2012, used a series of sophisticated underwater exploration vehicles to locate and characterize the pools, which they call the Kallisti Limnes, from ancient Greek for “most beautiful lakes.” A prior volcanic crisis in 2011 had led the researchers to initiate their investigation at a site of known hydrothermal activity within the Santorini caldera. During a preliminary reconnaissance of a large seafloor fault the University of Girona’s autonomous underwater vehicle (AUV) Girona 500 identified subsea layers of water with unusual chemical properties.

Following the AUV survey, the researchers then deployed HCMR’s Thetis human occupied vehicle. The submersible’s crew used robotic onboard chemical sensors to track the faint water column chemical signature up along the caldera wall where they discovered the pools within localized depressions of the caldera wall. Finally, the researchers sent a smaller remotely operated vehicle (ROV), to sample the pools’ hydrothermal fluids.

“We’ve seen pools within the ocean before, but they’ve always been brine pools where dissolved salt released from geologic formations below the seafloor creates the extra density and separates the brine pool from the surrounding seawater,” said Camilli. “In this case, the pools’ increased density isn’t driven by salt – we believe it may be the CO2 itself that makes the water denser and causes it to pool.”

Where is this CO2 coming from? The volcanic complex of Santorini is the most active part of the Hellenic Volcanic Arc. The region is characterized by earthquakes caused by the subduction of the African tectonic plate underneath the Eurasian plate. During subduction, CO2 can be released by magma degassing, or from sedimentary materials such as limestone which undergo alteration while being subjected to enormous pressure and temperature.

The researchers determined that the pools have a very low pH, making them quite acidic, and therefore, devoid of calcifying organisms. But, they believe, silica-based organisms could be the source of the opal in the pool fluids.

Until the discovery of these CO2-dense pools, the assumption has been that when CO2 is released into the ocean, it disperses into the surrounding water. “But what we have here,” says Camilli, “is like a ‘black and tan’ – think Guinness and Bass – where the two fluids actually remain separate” with the denser CO2 water sinking to form the pool.

The discovery has implications for the build up of CO2 in other areas with limited circulation, including the nearby Kolumbo underwater volcano, which is completely enclosed. “Our finding suggests the CO2 may collect in the deepest regions of the crater. It would be interesting to see,” Camilli said, adding it does have implications for carbon capture and storage.

Sub-seafloor storage is gaining acceptance as a means of reducing heat-trapping CO2 in the atmosphere and lessening the acidifying impacts of CO2 in the ocean. But before fully embracing the concept, society needs to understand the risks involved in the event of release.

Temperature sensors installed by the team revealed that the Kallisti Limnes were 5°C above that of surrounding waters. According to co-author Javier Escartin, “this heat is likely the result of hydrothermal fluid circulation within the crust and above a deeper heat source, such as a magma chamber.” These temperatures may provide a useful gauge to study the evolution of the system. Escartin added that “temperature records of hydrothermal fluids can show variations in heat sources at depth such as melt influx to the magma chamber. The pool fluids also respond to variations in pressure, such as tides, and this informs us of the permeability structure of the sub-seafloor.” Changes in the pools’ temperature and chemical signals may thus complement other monitoring techniques as useful indicators of increased or decreased volcanism.

This European – American research collaboration was funded through support from the EU Eurofleets program, Institut de Physique du Globe de Paris, Hellenic Centre for Marine Research, the US National Science Foundation, and NASA’s astrobiology program (ASTEP) which supports autonomous technology development to search for life on other planets. “From a technology perspective, it was a big step forward,” Camilli said.

Video

Note: The above post is reprinted from materials provided by Woods Hole Oceanographic Institution.

Jurassic saw fastest mammal evolution

Research led by Oxford University scientists shows that mammals were evolving up to ten times faster in the middle of the Jurassic than they were at the end of the period. An illustration showing docodonts, now extinct mammals that saw an explosion of skeletal and dental changes (including the special molar teeth that give them their name), in the Middle Jurassic. Credit: April Neander

Mammals were evolving up to ten times faster in the middle of the Jurassic than they were at the end of the period, coinciding with an explosion of new adaptations, new research shows.

Early mammals lived alongside the dinosaurs during the Mesozoic era (252-66 million years ago). They were once thought to be exclusively small nocturnal insect-eaters, but fossil discoveries of the past decade — particularly from China and South America — have shown that they developed diverse adaptations for feeding and locomotion, including gliding, digging, and swimming.

To find out when and how rapidly these new body shapes emerged a team led by Oxford University researchers did the first large-scale analysis of skeletal and dental changes in Mesozoic mammals. By calculating evolutionary rates across the entire Mesozoic, they show that mammals underwent a rapid ‘burst’ of evolutionary change that reached its peak around the middle of the Jurassic (200-145 million years ago).

The team comprised researchers from Oxford University in the UK and Macquarie University in Australia. A report of the research is published in Current Biology.

‘What our study suggests is that mammal ‘experimentation’ with different body-plans and tooth types peaked in the mid-Jurassic,’ said Dr Roger Close of Oxford University’s Department of Earth Sciences, lead author of the report. ‘This period of radical change produced characteristic body shapes that remained recognisable for tens of millions of years.’

The team recorded the number of significant changes to body plans or teeth that occurred in mammal lineages every million years. During the mid-Jurassic the frequency of such changes increased to up to 8 changes per million years per lineage, almost ten times that seen at the end of the period. This is exemplified by therian mammals, the lineage leading to placental mammals and marsupials, which were evolving 13 times faster than average in the mid-Jurassic, but which had slowed to a rate much lower than average by the later Jurassic. This ‘slow-down’ occurred despite the increase in the number of mammal species seen in this later period.

‘We don’t know what instigated this evolutionary burst. It could be due to environmental change, or perhaps mammals had acquired a ‘critical mass’ of ‘key innovations’ — such as live birth, hot bloodedness, and fur — that enabled them to thrive in different habitats and diversify ecologically,’ said Dr Close. ‘Once high ecological diversity had evolved, the pace of innovation slowed.’

Multituberculates, for instance, saw radical changes to their skeletons and teeth during the mid-Jurassic. However, by the end of the period they had evolved their rodent-like body shape and distinctive teeth, a form that, despite diversifying into hundreds of different species, they would generally retain until they went extinct around 130 million years later.

‘This is characteristic of other ‘adaptive radiation’ events of this kind, such as the famous ‘Cambrian explosion’,’ said Dr Close. ‘In the Jurassic we see a profusion of weird and wonderful bodies suddenly appear and these are then ‘winnowed down’ so that only the most successful survive. What we may have identified in this study is mammals’ own ‘Cambrian explosion’ moment, when evolutionary experimentation ran wild and the future shape of mammals was up for grabs.’

Reference:
Roger A. Close, Matt Friedman, Graeme T. Lloyd, Roger B.j. Benson. Evidence for a Mid-Jurassic Adaptive Radiation in Mammals. Current Biology, 2015 DOI: 10.1016/j.cub.2015.06.047

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

Feathered cousin of famous movie star dino unearthed in China

This is an artist’s impression of Zhenyuanlong suni. Credit: Chuang Zhao

A newly identified species of feathered dinosaur is the largest ever discovered to have a well-preserved set of bird-like wings, research suggests.

Palaeontologists working in China unearthed the fossil remains of the winged dinosaur — a close cousin of Velociraptor, which was made famous by the Jurassic Park films.

Researchers say its wings — which are very short compared with other dinosaurs in the same family — consisted of multiple layers of large feathers. They found that the species’ feathers were complex structures made up of fine branches stemming from a central shaft.

Although larger feathered dinosaurs have been identified before, none have possessed such complex wings made up of quill pen-like feathers, the team says. Scientists have known for some time that many species of dinosaur had feathers, but most of these were covered with simple filaments that looked more like hair than modern bird feathers.

This latest discovery suggests that winged dinosaurs with larger and more complex feathers were more diverse than previously thought.

The species belonged to a family of feathered carnivores that was widespread during the Cretaceous Period, and lived around 125 million years ago, the team says.

The near-complete skeleton of the animal — which is remarkably well preserved — was studied by scientists from the University of Edinburgh and the Chinese Academy of Geological Sciences. The fossil reveals dense feathers covered the dinosaur’s wings and tail.

The newly discovered species — named Zhenyuanlong suni — grew to more than five feet in length. Despite having bird-like wings, it probably could not fly, at least not using the same type of powerful muscle-driven flight as modern birds, researchers say.

It is unclear what function the short wings served. The species may have evolved from ancestors that could fly and used its wings solely for display purposes, in a similar way to how peacocks use their colourful tails, researchers say.

The study is published in the journal Scientific Reports. The research was supported by Natural Science Foundation of China, the European Commission, and the US National Science Foundation.

Dr Steve Brusatte, of the University of Edinburgh’s School of GeoSciences, who co-authored the study, said: “This new dinosaur is one of the closest cousins of Velociraptor, but it looks just like a bird. It’s a dinosaur with huge wings made up of quill pen feathers, just like an eagle or a vulture. The movies have it wrong — this is what Velociraptor would have looked like too.”

Professor Junchang Lü, of the Institute of Geology, Chinese Academy of Geological Sciences, who led the study, said: “The western part of Liaoning Province in China is one of the most famous places in the world for finding dinosaurs. The first feathered dinosaurs were found here and now our discovery of Zhenyuanlong indicates that there is an even higher diversity of feathered dinosaurs than we thought. It’s amazing that new feathered dinosaurs are still being found.”

Reference:
Junchang Lü, Stephen L. Brusatte. A large, short-armed, winged dromaeosaurid (Dinosauria: Theropoda) from the Early Cretaceous of China and its implications for feather evolution. Scientific Reports, 2015; 5: 11775 DOI: 10.1038/srep11775

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

Plate tectonics may have driven the evolution of life on Earth

The Cambrian explosion about 540 million years ago was when all the major living groups (phyla) of animal life appeared. Did a rise in oceanic trace elements initiate this event? Credit: Wikia, CC BY-SA

When Charles Darwin published his theory of evolution by natural selection in 1859, the world hadn’t even heard of plate tectonics. The notion that continents drifted on molten rock currents deep in the Earth’s mantle was unimaginable.

So it would have come as a shock to Darwin to think the movement of the Earth’s continental plates could have been a major driver of evolutionary change in all life.

In our research, published this month in Gondwana Research, we suggest that the regular collision of tectonic plates over the past 700 million years has been a prime driver of evolutionary change on Earth.

The essentials for life

We used laser technology housed in the Earth Science laboratories at the University of Tasmania to analyse more than 4,000 pyrite grains from seafloor mudstone samples collected from around the globe.

This enabled us to determine how concentrations of trace elements in the oceans have varied over the 700 million years. Trace elements included copper, zinc, phosphorus, cobalt and selenium, which are necessary for nearly all life – from marine phytoplankton through to humans – to function.

The most surprising finding was that there were certain periods in Earth’s history when nutrient trace elements were highly enriched in the oceans, and other periods when levels of these critical trace elements were very low.

The nutrient-rich periods promoted rapid plankton growth in the short term, and this appears to correlate with periods of increased evolutionary change. An example of this is the rapid rise in trace elements preceding the Ediacaran (635 to 542 million years ago) and Cambrian (541 to 485 mya) periods, a time when multicellular animal life took off in a big way.

The Cambrian explosion, around 540 million years ago, is when most major groups of living animals appeared. This corresponds to a time when essential trace elements were peaking in the oceans, thus nutrient levels were very high.

The nutrient-poor periods caused depletion of plankton and promoted a slow-down in rates of diversification and ultimately could have played a role in three major mass extinction events. These occurred at the end of the Ordovician, Devonian and Triassic periods.

Although several possible explanations are given for these extinctions events, depletion in oceanic trace elements might be another plausible factor. Work is currently underway demonstrating that these events are tied to rapid declines in certain essential trace elements, particularly selenium.

Plate tectonics and nutrient cycles

Nutrients in the oceans ultimately come from weathering and erosion of rocks on thecontinents. Weathering breaks down the minerals in the rocks and releases thenutrient trace elements, which nourish life. Thus when weathering and erosion rates increase for extended periods, more nutrients are supplied to the oceans.

In the long term of geological history, erosion rates rise dramatically duringmountain building events caused by the gradual collision of tectonic plates.

Geologists have known since the 1960s that collisions of tectonic plates lead to the formation of huge mountain ranges. The Himalayas were formed when India, drifting northwards after splitting off from the supercontinent of Gondwana, slammed into Asia and pushed up the Tibetan Plateau. These collisions are called called orogenic events and their timing through Earth’s history is now well established.

Continued erosion eventually depletes the surface of nutrients, causing a drop in the ocean’s nutrients. This might have led to extinction events in the seas.

This is the first time nutrient trace element curves have been developed that demonstrate the relationship between tectonic collisions and the generation of cycles of nutrients.

While the link between these nutrient cycles as drivers of evolution and factors in mass extinction events remains to be proven, it really makes us think about evolution in a broad sense. Plate tectonics and evolution both operate on the same time scale of millions of years, and it seems logical that they could be causally related.

The relationship between increased nutrients in the oceans with bursts of evolutionary change are clearly correlated for the early part of the cycles, but less clear is the correlation with the evolution of advanced land animals.

Life out of the oceans

The origin of the first land animals, tetrapods about 370 million years ago, corresponds with a decrease in oceanic nutrients and a series of mass extinction events in the oceans. This could explain why certain sarcopterygian fishes with robust limbs left the seas when they did in order to leave the nutrient-poor ocean and make out on land.

But the first appearance of dinosaurs and mammals in the early Triassic, about 225 million years ago, has no correlation with trace element abundance.

Perhaps the cycles pertain mainly to biodiversity in the oceans. There is certainly a close correlation with the drop in nutrients and some global oceanic mass extinctions. These events are being tested and explored further in further research on selenium, to be released soon.

Note: The above post is reprinted from materials provided by The Conversation.
This story is published courtesy of The Conversation (under Creative Commons-Attribution/No derivatives).

Mud volcano

Cold Mud Pots near Glen Blair town site, Fort Bragg, CA. Credit: MendoMann

What is Mud volcano?

Mud volcano or mud dome refers to formations created by geo-exuded slurries (usually including water) and gases. There are several geological processes that may cause the formation of mud volcanoes. Mud volcanoes are not true (igneous) volcanoes as they produce no lava. The earth continuously exudes a mud-like substance, which may sometimes be referred to as a “mud volcano”. Mud volcanoes may range in size from merely 1 or 2 meters high and 1 or 2 meters wide, to 700 meters high and 10 kilometers wide. Smaller mud exudations are sometimes referred to as mud-pots. The largest mud volcano, Indonesia’s Lusi, is 10 kilometres (6 mi) in diameter.

The mud produced by mud volcanoes is most typically formed as hot water, which has been heated deep below the earth’s surface, begins to mix and blend with subterranean mineral deposits, thus creating the mud slurry exudate. This material is then forced upwards through a geological fault or fissure due to local subterranean pressure imbalances. Mud volcanoes are associated with subduction zones and about 1100 have been identified on or near land. The temperature of any given active mud volcano generally remains fairly steady and is much lower than the typical temperatures found in igneous volcanoes. Mud volcano temperatures can range from near 100 °C (212 °F) to occasionally 2 °C (36 °F), some being used as popular “mud baths.”

About 86% of the gas released from these structures is methane, with much less carbon dioxide and nitrogen emitted. Ejected materials are most often a slurry of fine solids suspended in water that may contain a mixture of salt, acids and various hydrocarbons.

Possible mud volcanoes have been identified on Mars.

What causes a mud volcano? “Details”

A mud volcano may be the result of a piercement structure created by a pressurized mud diapir that breaches the Earth’s surface or ocean bottom. Their temperatures may be as low as the freezing point of the ejected materials, particularly when venting is associated with the creation of hydrocarbon clathrate hydrate deposits. Mud volcanoes are often associated with petroleum deposits and tectonic subduction zones and orogenic belts; hydrocarbon gases are often erupted. They are also often associated with lava volcanoes; in the case of such close proximity, mud volcanoes emit incombustible gases including helium, whereas lone mud volcanoes are more likely to emit methane.

Approximately 1,100 mud volcanoes have been identified on land and in shallow water. It has been estimated that well over 10,000 may exist on continental slopes and abyssal plains.

Features

  • Gryphon: steep-sided cone shorter than 3 meters that extrudes mud
  • Mud cone: high cone shorter than 10 meters that extrudes mud and rock fragments
  • Scoria cone: cone formed by heating of mud deposits during fires
  • Salse: water-dominated pools with gas seeps
  • Spring: water-dominated outlets smaller than 0.5 metres
  • Mud shield

Emissions

Most liquid and solid material is released during eruptions, but seeps occur during dormant periods.

The mud is rich in halite (rock salt).

First-order estimates of mud volcano emissions have been made (1 Tg = 1 million metric tonnes).

  • 2002: L.I. Dimitrov estimated that 10.2–12.6 Tg/yr of methane is released from onshore and shallow offshore mud volcanoes.
  • 2002: Etiope and Klusman estimated at least 1–2 and as much as 10–20 Tg/yr of methane may be emitted from onshore mud volcanoes.
  • 2003: Etiope, in an estimate based on 120 mud volcanoes: “The emission results to be conservatively between 5 and 9 Tg/yr, that is 3–6% of the natural methane sources officially considered in the atmospheric methane budget. The total geologic source, including MVs (this work), seepage from seafloor (Kvenvolden et al., 2001), microseepage in hydrocarbon-prone areas and geothermal sources (Etiope and Klusman, 2002), would amount to 35–45 Tg/yr.”
  • 2003: analysis by Milkov et al. suggests that the global gas flux may be as high as 33 Tg/yr (15.9 Tg/yr during quiescent periods plus 17.1 Tg/yr during eruptions). Six teragrams per year of greenhouse gases are from onshore and shallow offshore mud volcanoes. Deep-water sources may emit 27 Tg/yr. Total may be 9% of fossil CH4 missing in the modern atmospheric CH4 budget, and 12% in the preindustrial budget.
  • 2003: Alexei Milkov estimated approximately 30.5 Tg/yr of gases (mainly methane and CO2) may escape from mud volcanoes to the atmosphere and the ocean.
  • 2003: Achim J. Kopf estimated 1.97×1011 to 1.23×1014 m³ of methane is released by all mud volcanoes per year, of which 4.66×107 to 3.28×1011 m³ is from surface volcanoes. That converts to 141–88,000 Tg/yr from all mud volcanoes, of which 0.033–235 Tg is from surface volcanoes.

Where Are the Mud Volcanoes?

  • Europe
  • Asia
    • Lusi (Indonesia)
    • Central Asia
    • Azerbaijan
    • Iran
    • India
    • Pakistan
    • Philippines
    • Other Asian locations
      • China has a number of mud volcanoes in Xinjiang province.
      • Some active mud volcanoes are in Oesilo (Oecusse District, East Timor). Arthur Wichmann reports a mud volcano in Bibiluto (Viqueque District), which erupted between 1856 and 1879.
      • There are mud volcanoes at the Minn Buu Township, Magway division in Myanmar (Burma).
      • There are two active mud volcanoes in South Taiwan and several inactive ones. The Wushan Mud Volcanoes (烏山頂泥火山 in Chinese) are in the Yanchao District of Kaohsiung City. There are active mud volcanoes in Wandan township of Pingtung county.
      • There are mud volcanoes on the island of Pulau Tiga, off the western coast of the Malaysian state of Sabah on Borneo.
      • A drilling accident offshore of Brunei on Borneo in 1979 caused a mud volcano which took 20 relief wells and nearly 30 years to halt.
  • North America
    • Yellowstone’s “Mud Volcano”
  • South America
    • Venezuela
    • Colombia

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

125-million-year-old ‘baby’ found inside fossil

Tiny fossilised eggs, like the one shown above, discovered in Thailand have been found to contain the remains of a 125 million year old lizard embryo related to modern Komodo dragons and slow worms. Unlike almost all living lizards, however, this ancient species, which has yet to be named, laid hard shelled eggs 

Tiny fossil eggs long thought to harbour the embryos of dinosaurs or primitive birds, in fact contained unhatched baby lizards—the oldest ever found, scientists said Wednesday.

The eggs, roughly the size of a one-euro coin or sparrow egg, are about 125 million years old, and were discovered in Thailand in 2003.

They have hard shells, unusual for lizards, and initial examinations concluded they must have been laid by a small carnivorous dinosaur or early type of bird.

Not satisfied, an international team of scientists decided to look inside the fossil eggs using the powerful European Synchrotron Radiation Facility (ESRF) in Grenoble, France.

High-resolution, ultra-bright X-rays allowed them to observe the finest details of the minute bones inside the six knob-covered shells, and recreate the skeletons in 3D.

They found features of a “hitherto unknown lizard”, including a long and slender skull ending in a pointed snout, and a “quadrate”—a jaw articulation bone found in the lizard family.

“These embryos were neither dinosaurs, nor birds, but lizards from a group called anguimorph,” the ESRF said in a statement.

The group includes komodo dragons and mosasaurs, a type of extinct marine reptile.

“The discovery of anguimorphs in hard-shelled eggs comes as a considerable surprise,” said the statement—and recast the evolution of lizard reproduction.

“So far, only geckos were known to lay hard-shell eggs.”

The study was published in the journal PLOS ONE.

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

Discovery optimises uranium extraction process

Yellow cake uranium, a solid form of uranium oxide produced from uranium ore. Credit: Nuclear Regulatory Commission

EXTRACTIVE metallurgists from Murdoch University have discovered the dissolution mechanism for a mineral previously considered to be unrecoverable and discarded as waste.

Brannerite (UTi2O6) is the most common refractory uranium mineral and accounts for up to 15 per cent of uranium currently unrecovered in extraction, translating into tens of millions of lost dollars for industry.

However, Dr Aleks Nikoloski and PhD candidate Rorie Gilligan have discovered how brannerite can be extracted relatively easily, all thanks to a counter-intuitive approach.

“The traditional wisdom in extractive metallurgy is that if you use more aggressive corrosive conditions, say by increasing the acid concentration, minerals will dissolve allowing the metal to come out, but it’s not the case with brannerite because of its chemical properties,” Dr Nikoloski says.

“While it can be extracted with high temperatures, high free acid concentrations and long leaching times, the process isn’t efficient or economical.

“By gaining an understanding of the chemical processes of brannerite, we have found a dissolution mechanism that supports effective extraction under relatively mild conditions.”

This discovery is the result of a thorough literature review by Mr Gilligan and several years of testing in the lab by a team lead by Dr Nikoloski.

Historical research acts as good springboard

“In doing my literature review, I found a number of largely forgotten studies from the 1950s and ‘60s looking at brannerite extraction,” Mr Gilligan says.

“We took these as a starting point and applied more current knowledge.

“We started by considering how brannerite behaves in the standard sulphuric acid/iron sulfate media and then looked at how it behaved when we introduced other substances, such as phosphates and fluoride, which are known to occur in natural deposits.

“There was no research into how these interacted with brannerite, so by taking a step-by-step approach we were able to better understand the mineral’s chemical processes.”

When Mr Gilligan applied this knowledge to extraction, the results prompted Dr Nikoloski to request that the samples be re-examined.

“I wanted to ensure we were using brannerite,” Dr Nikoloski says.

“At first I couldn’t believe the results. We were getting an extraction rate of 80 to 90 per cent for a mineral that was supposed to be refractory.”

Mr Gilligan says the amount of uranium that will be recovered from brannerite will depend on the geological composition of each ore deposit.

Brannerite is found in significant concentrations in deposits in Mount Isa, Queensland and Crocker Well in South Australia.

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

Where Does Water Go When It Doesn’t Flow?

This view of Henry’s Lake in Utah’s Uinta Mountains shows several ways water on land reaches the atmosphere: It evaporates from lake waters, streams and soils and also is transpired or “exhaled” by trees and other plants. Such evaporation – as well as from the ocean – helps form clouds in the sky. In a new study in the journal Science, University of Utah researchers determined how much of the rain and snowmelt that falls on the land moves to the atmosphere from plant transpiration and evaporation from soil and surface waters. Credit: Stephen Good/University of Utah

More than a quarter of the rain and snow that falls on continents reaches the oceans as runoff. Now a new study helps show where the rest goes: two-thirds of the remaining water is released by plants, more than a quarter lands on leaves and evaporates and what’s left evaporates from soil and from lakes, rivers and streams.

“The question is, when rain falls on the landscape, where does it go?” says University of Utah geochemist Gabe Bowen, senior author of the study published today in the journal Science. “The water on the continents sustains all plant life, all agriculture, humans, aquatic ecosystems. But the breakdown – how much is used for those things – has always been unclear.”

“Some previous estimates suggested that more water was used by plants than we find here,” he adds. “It means either that plants are less productive globally than we thought, or plants are more efficient at using water than we assumed.”

University of Utah hydrologist Stephen Good, the study’s first author, says, “We’ve broken down the different possible pathways that water takes as it moves from rainfall [and snowfall] through soils, plants and rivers. Here we’ve found the proportions of water that returns to the atmosphere though plants, soils and open water.”

The study used hydrogen isotope ratios of water in rain, rivers and the atmosphere from samples and satellite measurements to conclude that of all precipitation over land – excluding river runoff to the oceans—these amounts are released by other means:

• 64 percent (55,000 cubic kilometers or 13,200 cubic miles) is released or essentially exhaled by plants, a process called transpiration. This is lower than estimated by recent research, which concluded plant transpiration accounted for more than 80 percent of water that falls on land and does not flow to the seas, Bowen says.
• 6 percent (5,000 cubic kilometers or 1,200 cubic miles) evaporates from soils.
• 3 percent (2,000 cubic kilometers or 480 cubic miles) evaporates from lakes, streams and rivers.
• Previous research indicated the other 27 percent (23,000 cubic kilometers or 5,520 cubic miles) falls on leaves and evaporates, a process called interception.

“It’s important to understand the amount of water that goes through each of these pathways,” Good says. “The most important pathway is the water that passes through plants because it is directly related to the productivity of natural and agricultural plants.”

In another key finding, the researchers showed how much rainwater or snowmelt passing through soils is available for plants to use before it enters groundwater, lakes or streams. They found this “connectivity” is 38 percent: Only 38 percent of water entering groundwater, lakes or rivers interacts with soil, and the rest “moves rapidly into groundwater and lakes and rivers without spending much time in the soil,” Bowen says.

“Lot of things happen in soils: nutrients, fertilizers, contaminants, various biological processes,” he adds. “If water that goes to streams and groundwater moves rapidly through soil, it has less interaction with those processes. It means the soils and rest of the hydrologic cycle are somewhat separated. If we want to predict future climate change, hydrologic change and water quality, we need to account for the fact that most water doesn’t interact with soils before it reaches streams and groundwater.”

Significance: for agriculture, water supplies, climate

Good is a research assistant professor and Bowen is an associate professor of geology and geophysics at the University of Utah. They conducted the study with David Noone, of Oregon State University, where Good joins the faculty this fall. Funding came from the Department of Defense and the National Science Foundation, where two program directors praised the findings.

“These scientists found a way to answer basic questions about what happens to rainwater when it falls on land,” says Eric DeWeaver, of NSF’s Division of Atmospheric and Geospace Sciences. “The answers have important implications for water quality, plant productivity and peak streamflow. They give us a window on the inner workings of ecosystems and watersheds that’s scientifically fascinating and useful.”

“Getting what’s called Earth’s ‘water balance’ right is the key to understanding how our climate and ecosystems interact,” says Henry Gholz, of NSF’s Division of Environmental Biology. “This new analysis offers an estimate of hard-to-come-by global water measurements: water used by plants and water that evaporates from land. By knowing these amounts, we can better understand how ecosystems, including watersheds, work. In a decade when our reserves of freshwater are declining – in some cases to critically low levels – this information couldn’t be timelier.”

Good says that knowing how much water plants release or transpire is important “so that we can have an understanding how productive ecosystems and agriculture are, because how much water plants use determines how much food we get and how many leaves are on the trees.”

Earth’s water cycle is changing as climate warms, “so given shifts in future water availability, we also will see shifts in ecosystems and agriculture,” Good says. “So understanding the connection between the water cycle and plant growth is important.

For example, when leaves release water, they consume carbon dioxide, the major climate-warming gas. Soil doesn’t do that. So knowing how much water plants transpire “helps us understand how plants contribute to reducing global warming,” Bowen says.

Evapotranspiration from land – in context

To put the new study in context, consider previous research showing every year about 496,000 cubic kilometers or 119,000 cubic miles of water evaporates from the oceans and continents and then becomes rain that falls over the oceans and continents. Of the global rainfall amount, 77 percent of precipitation falls over oceans and 23 percent over continents. Because some continental precipitation runs off to the seas, 83 percent of global evaporation comes from the oceans and only 17 percent from continents.

The new study deals with the fate of that 17 percent, which amounts to 85,000 cubic kilometers or 20,400 cubic miles of water. In other words, all the water that doesn’t fall or flow into the oceans would fill 20,400 cubes of water 1 mile on each side. (The study excluded water evaporating to the atmosphere from snow because earlier research indicates it is less than 1 percent, Good says.)

How the study was performed

The study used data from two sources. First, a global network of isotopes and precipitation collected since the 1950s by the International Atomic Energy Agency. It includes measurements of deuterium – the heavy form or isotope of hydrogen. Deuterium is hydrogen-2 rather than the common isotope hydrogen-1. The IAEA data include measurements of deuterium in rainfall from about 500 stations around the world.

Second, the researchers used measurements made by NASA’s Aura satellite of deuterium concentrations in water vapor near Earth’s surface.

Each form of water has a distinct deuterium-hydrogen ratio, some of which Good and Bowen determined in a related study in another journal. Water vapor evaporated after being intercepted by leaves has deuterium-hydrogen ratios the same as rainwater. Water evaporated from lakes and streams has a relatively low deuterium-hydrogen ratio. Water evaporated from soil is similar, but the water left behind has a higher deuterium-hydrogen ratio, and thus so does water taken up and then transpired by plants, Bowen says.

The new study accounted for each of these isotopic signatures in a computer simulation of global movements of water between the land and atmosphere. By running the simulation thousands of times and testing the resulting estimates of river water and evapotranspiration isotope ratios against independent data, Good was able to show that a limited number of simulations matched the data. These gave a narrow range of estimates for how much water was released to the atmosphere by each pathway.

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

Surprisingly high geothermal heating revealed beneath West Antarctic Ice Sheet

In this 2013 image, Ken Mankoff, then at the University of California, Santa Cruz, monitors the borehole for the Whillans Ice Stream Subglacial Access Research Drilling (WISSARD) program. Credit: Reed Scherer, NSF 

The amount of heat flowing toward the base of the West Antarctic ice sheet from geothermal sources deep within the Earth is surprisingly high, according to a new study led by researchers at the University of California (UC), Santa Cruz.

The results, published on July 10 in the online journal Science Advances, provide important data for researchers trying to predict the fate of the ice sheet, which has experienced rapid melting over the past decade.

Lead author Andrew Fisher, a professor of Earth and planetary sciences at UC Santa Cruz, emphasized that the geothermal heating reported in this study does not explain the alarming loss of ice from West Antarctica that has been documented by other researchers.

“The ice sheet developed and evolved with the geothermal heat flux coming up from below–it’s part of the system. But this could help explain why the ice sheet is so unstable,” he said.

The study draws upon data collected by a large Antarctic drilling project, funded by an award from the National Science Foundation’s Division of Polar Programs, called WISSARD (Whillans Ice Stream Subglacial Access Research Drilling), for which UC Santa Cruz is one of three lead institutions, the others being Montana State University and Northern Illinois University. The Division manages the U.S. Antarctic Program, through which it coordinates all U.S. scientific research on the southernmost continent.

Scott Borg, who heads the Division’s Antarctic sciences section, noted that the multidiscplinary WISSARD project has produced a number of significant research results in recent years that are helping to advance scientific understanding in disparate fields, from biology to the geosciences.

“The WISSARD findings, including this latest discovery about geothermal heat,” he said, “are helping us to assemble a deeper understanding of the nature of extreme ecosystems in Antarctica, and, possibly, similar ecosystems elsewhere in the solar system, as well helping us to understand some of the many dynamic processes that govern the behavior of the massive Antarctic ice sheets.”

The research team used a special thermal probe, designed and built at UC Santa Cruz, to measure temperatures in sediments below Subglacial Lake Whillans, which lies beneath half a mile of ice. After boring through the ice sheet with a special hot-water drill, researchers lowered the probe through the borehole until it buried itself in the sediments below the subglacial lake. The probe measured temperatures at different depths in the sediments, revealing a rate of change in temperature with depth about five times higher than that typically found on continents. The results indicate a relatively rapid flow of heat towards the bottom of the ice sheet.

High heat flow below the West Antarctic ice sheet may also help explain the presence of lakes beneath it and why parts of the ice sheet flow rapidly as ice streams. Water at the base of the ice streams is thought to provide the lubrication that speeds their motion, carrying large volumes of ice out onto the floating ice shelves at the edges of the ice sheet. Fisher noted that the geothermal measurement was from only one location, and heat flux is likely to vary from place to place beneath the ice sheet.

“This is the first geothermal heat flux measurement made below the West Antarctic ice sheet, so we don’t know how localized these warm geothermal conditions might be. This is a region where there is volcanic activity, so this measurement may be due to a local heat source in the crust,” Fisher said.

This geothermal heating contributes to melting of basal ice, which supplies water to a network of subglacial lakes and wetlands that scientists have discovered underlies a large region of the ice sheet. In a separate study published last year in Nature, the WISSARD microbiology team reported an abundant and diverse microbial ecosystem in the same lake. Warm geothermal conditions may help to make subglacial habitats more supportive of microbial life, and could also drive fluid flow that delivers heat, carbon, and nutrients to these communities.

According to co-author Slawek Tulaczyk, a professor of Earth and planetary sciences at UC Santa Cruz and one of the WISSARD project leaders, the geothermal heat flux is an important value for the computer models scientists are using to understand why and how quickly the West Antarctic ice sheet is shrinking.

“It is important that we get this number right if we are going to make accurate predictions of how the West Antarctic ice sheet will behave in the future, how much it is melting, how quickly ice streams flow, and what the impact might be on sea level rise,” Tulaczyk said. “I waited for many years to see a directly measured value of geothermal flux from beneath this ice sheet.”

Antarctica’s huge ice sheets are fed by snow falling in the interior of the continent. The ice gradually flows out toward the edges. The West Antarctic ice sheet is considered less stable than the larger East Antarctic ice sheet because much of it rests on land that is below sea level, and the ice shelves at its outer edges are floating on the sea. Recent studies by other research teams have found that the ice shelves are melting due to warm ocean currents now circulating under the ice, and the rate at which the ice shelves are shrinking is accelerating. These findings have heightened concerns about the overall stability of the West Antarctic ice sheet.

The geothermal heat flux measured in the new study was about 285 milliwatts per square meter, which is like the heat from one small LED Christmas-tree light per square meter, Fisher said. The researchers also measured the upward heat flux through the ice sheet (about 105 milliwatts per square meter) using an instrument developed by coauthor Scott Tyler at the University of Nevada, Reno. That instrument was left behind in the WISSARD borehole as it refroze, and the measurements, based on laser light scattering in a fiber-optic cable, were taken a year later. Combining the measurements both below and within the ice enabled calculation of the rate at which melt water is produced at the base of the ice sheet at the drill site, yielding a rate of about half an inch per year.

In addition to Fisher, Tulaczyk and Tyler, the coauthors of the paper include Ken Mankoff, who earned his doctorate at UC Santa Cruz and is now a research associate at Pennsylvania State University, and current UC Santa Cruz graduate student Neil Foley.

Note: The above post is reprinted from materials provided by National Science Foundation.

Who is the boss?: Head-butting and canine display during male-male combat first appeared some 270 million years ago.

Head-butting and canine display during male-male combat first appeared some 270 million years ago.

This is what researchers from the Evolutionary Studies Institute at Wits found when they conducted an updated and more in-depth study of the herbivorous mammalian ancestor, Tiarajudens eccentricus, discovered four years ago.

Through this study, the Brazil and South Africa researchers can now present a meticulous description of the skull, skeleton and dental replacement of this Brazilian species. And they learned that 270 million years ago, the interspecific combat and fighting we see between male deer today were already present in these forerunners of mammals.

The Brazilian researcher, Dr Juan Carlos Cisneros, and his co-researchers from the Evolutionary Studies Institute at the University of the Witwatersrand, Professor Fernando Abdala and Dr Tea Jashasvili, have published their results in the journal Royal Society Open Science on 15 July 2015.

Brazilian and South African cousins

Saber-teeth are known to belong to the large Permian predators’ gorgonopsians (also known as saber-tooth reptiles), and in the famous saber-tooth cats from the Ice Age.

When Tiarajudens eccentricus was discovered it had some surprises install: Despite large protruding saber-tooth canines and occluding postcanine teeth, it was an herbivore.

The discovery of this Brazilian species also allowed for a reanalysis of the South African species Anomocephalus africanus, discovered 10 years earlier. The two species have several similar features that clearly indicated they are closely related but the African species lack of the saber-tooth canines of its Brazilian cousin. In the Middle Permian, where these Gondwana cousins were living, around 270 million years ago, the first communities with diverse, abundant tetrapod herbivores were evolving.

Male-male fighting

In deer today enlarged canines are used in male-male displays during fighting. The long canine in the herbivore T. eccentricus is interpreted as an indication of its use in a similar way, and is the oldest evidence where male herbivores have used their canines during fights with rivals.

“It is incredible to think that features found in deer such as the water deer, musk deer and muntjacs today were already represented 270 million years ago,” says Cisneros.

The researchers found the Tiarajudens’ marginal teeth are also located in a bone from the palate called epipterygoid. “This is an extraordinary condition as no other animal in the lineage leading to mammals show marginal dentition in a bone from the palate,” says Abdala.

Head-butting

In another group of mammal fossil relatives, dinocephalians – that lived at the same time as anomodonts, some of the bones in their foreheads were massively thickened. This can be interpreted as being used in head-butting combat, a modern behaviour displayed by several deer species today.

“Fossils are always surprising us. Now they show us unexpectedly that 270 million years ago two forms of interspecific combat represented in deer today, were already present in the forerunners of mammals,” says Cisneros.

Reference:
“Tiarajudens eccentricus and Anomocephalus africanus, two bizarre anomodonts (Synapsida, Therapsida) with dental occlusion from the Permian of Gondwana.” DOI: 10.1098/rsos.150090

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

Curiosity rover finds evidence of Mars’ primitive continental crust

Igneous clast named Harrison embedded in a conglomerate rock in Gale crater, Mars, shows elongated light-toned feldspar crystals. The mosaic merges an image from Mastcam with higher-resolution images from ChemCam’s Remote Micro-Imager. Credit: NASA/JPL-Caltech/LANL/IRAP/U. Nantes/IAS/MSSS.

The ChemCam laser instrument on NASA’s Curiosity rover has turned its beam onto some unusually light-colored rocks on Mars, and the results are surprisingly similar to Earth’s granitic continental crust rocks. This is the first discovery of a potential “continental crust” on Mars.

“Along the rover’s path we have seen some beautiful rocks with large, bright crystals, quite unexpected on Mars” said Roger Wiens of Los Alamos National Laboratory, lead scientist on the ChemCam instrument. “As a general rule, light-colored crystals are lower density, and these are abundant in igneous rocks that make up the Earth’s continents.”

Mars has been viewed as an almost entirely basaltic planet, with igneous rocks that are dark and relatively dense, similar to those forming the Earth’s oceanic crust, Wiens noted. However, Gale crater, where the Curiosity rover landed, contains fragments of very ancient igneous rocks (around 4 billion years old) that are distinctly light in color, which were analyzed by the ChemCam instrument.

French and US scientists observed images and chemical results of 22 of these rock fragments. They determined that these pale rocks are rich in feldspar, possibly with some quartz, and they are unexpectedly similar to Earth’s granitic continental crust. According to the paper’s first author, Violaine Sautter, these primitive Martian crustal components bear a strong resemblance to a terrestrial rock type known to geologists as TTG (Tonalite-Trondhjemite-Granodiorite), rocks that predominated in the terrestrial continental crust in the Archean era (more than 2.5 billion years ago).

The results were published this week in Nature Geoscience, “In situ evidence for continental crust on early Mars.”

Gale crater, excavated about 3.6 billion years ago into rocks of greater age, provided a window into the Red Planet’s primitive crust. The crater walls provided a natural geological cut-away view 1-2 miles down into the crust. Access to some of these rocks, strewn along the rover’s path, provided critical information that could not be observed by other means, such as by orbiting satellites.

Reference:
V. Sautter, M. J. Toplis, R. C. Wiens, A. Cousin, C. Fabre, O. Gasnault, S. Maurice, O. Forni, J. Lasue, A. Ollila, J. C. Bridges, N. Mangold, S. Le Mouélic, M. Fisk, P.-Y. Meslin, P. Beck, P. Pinet, L. Le Deit, W. Rapin, E. M. Stolper, H. Newsom, D. Dyar, N. Lanza, D. Vaniman, S. Clegg, J. J. Wray. In situ evidence for continental crust on early Mars. Nature Geoscience, 2015; DOI: 10.1038/ngeo2474

Note: The above post is reprinted from materials provided by DOE/Los Alamos National Laboratory.

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