From: "Lin Kerns email@example.com [geology2]" <firstname.lastname@example.org>
To: Geology2 <email@example.com>
Sent: Wednesday, March 30, 2016 8:22 AM
Subject: [Geology2] Unraveling a geological mystery using lasers from space
Unraveling a geological mystery using lasers from space
- March 29, 2016
- University of Toronto
- Drumlins and megaridges are all part of a single family of landforms formed by erosion, new research concludes. Shaped like an upturned boat, drumlin hills are found clustered together in their hundreds and thousands in distinct fields called swarms. They are the most common landform across large areas of northern North America and Europe, marking the footprint of great sheets that formed during past ice ages.
Shaped like an upturned boat, drumlin hills (pictured above) are found clustered together in their hundreds and thousands in distinct fields called swarms. They're the most common landform across large areas of northern North America and Europe, marking the footprint of massive ice sheets that formed during past ice ages.Credit: University of Toronto ScarboroughIt's a mystery that has stumped geologists for more than a century.Now, thanks to new technology -- including satellite laser imagery -- researchers may be one step closer to understanding the origins of an archetypal landform: the drumlin hill."Drumlin hills are the most studied and yet the most enigmatic ice age landform," says U of T Scarborough geology professor Nick Eyles. "Thanks to high resolution satellite imagery and new technology like LiDAR, we're literally seeing the surface of the planet for the first time and finding major surprises in the process."Shaped like an upturned boat, drumlin hills are found clustered together in their hundreds and thousands in distinct fields called swarms. They are the most common landform across large areas of northern North America and Europe, marking the footprint of great sheets that formed during past ice ages.The question that's stumped geologists since drumlins were first studied more than 150 years ago is whether they were built up progressively or sculpted out of older sediment. Eyles and his team including PhD candidate Shane Sookhan and undergraduate student Lina Arbelaez-Moreno were able to determine that drumlins are simply streamlined "islands" of sediment that are often bisected to form kilometre-long skinny megaridges. Their research, published in the journal Sedimentary Geology, suggests that drumlins and megaridges are all part of a single family of landforms formed by erosion."The new data we were able to obtain shows that these landforms occur on hard rock, which stresses the importance of sculpting below the base of the ice sheet," says Arbelaez-Moreno.To illustrate the importance of megaridges Eyles points to research being done on the modern Greenland and Antarctica ice sheets. These are slow moving ice sheets but contain faster flowing corridors called 'ice streams' that are up to tens of kilometres wide, hundreds of kilometres in length and can move as fast as 1 km annually."They're essentially arteries moving huge volumes of ice toward the margin of the ice sheet," explains Eyles. The thinning and retreating of modern ice streams in a warming world has exposed their underlying beds which are seen to be megaridged, and that appears to allow the ice to flow faster across its bed by creating a slippery low-friction surface, he adds.The last Canadian ice sheet (Laurentide) was as much as 3 km thick and behaved in exactly the same way, says Eyles. "The transition from drumlins to megaridges may record the final gasp of the ice sheet as it warmed up and began to stream over its bed."Debris that is being dragged under these streams is highly erosive -- "think of sandpaper'' says Sookhan -- and the process sculpts the underlying surface, allowing drumlins to be progressively whittled down into longer and longer megaridges.The data used by the researchers relied on high resolution satellite imagery and new technologies including LiDAR, which uses hundreds of laser beams fired from planes onto the land below. The result is the creation of highly accurate topographic maps even where landscapes are covered by trees or water."We still have a lot to learn about how drumlins are formed, but this imaging technique has changed the science by providing a new way of looking at glacial landscapes," says Sookhan.The megaridges identified by Eyles and his team are particularly common around Peterborough, Ontario at the site of one of the most easily accessible drumlin fields in Canada."You could say drumlins are quintessentially Canadian," says Eyles. "They do occur in Europe, but are far more common here because almost the entire country was covered by the Laurentide Ice Sheet during the last ice age."
- Nick Eyles, Niko Putkinen, Shane Sookhan, Lina Arbelaez-Moreno. Erosional origin of drumlins and megaridges. Sedimentary Geology, 2016; DOI: 10.1016/j.sedgeo.2016.01.006
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Scientists from the University of Liverpool have developed computer models of the bodies of sauropod dinosaurs to examine the evolution of their body shape.
Sauropod dinosaurs include the largest land animals to have ever lived. Some of the more well-known sauropods include Diplodocus, Apatosaurus and Brontosaurus. They are renowned for their extremely long necks, long tails as well as four thick, pillar-like legs and small heads in relation to their body.
To date, however, there have been only limited attempts to examine how this unique body-plan evolved and how it might be related to their gigantic body size. Dr Karl Bates from the University's Department of Musculoskeletal Biology and his colleagues used three-dimensional computer models reconstructing the bodies of sauropod dinosaurs to analyse how their size, shape and weight-distribution evolved over time.
Dr Bates found evidence that changes in body shape coincided with major events in sauropod evolutionary history such as the rise of the titanosaurs. The early dinosaurs that sauropods evolved from were small and walked on two legs, with long tails, small chests and small forelimbs. The team estimate that this body shape concentrated their weight close to the hip joint, which would have helped them balance while walking bipedally on their hind legs.
As sauropods evolved they gradually altered both their size and shape from this ancestral template, becoming not only significantly larger and heavier, but also gaining a proportionally larger chest, forelimbs and in particular a dramatically larger neck.
The team's findings show that these changes altered sauropods' weight distribution as they grew in size, gradually shifting from being tail-heavy, two-legged animals to being front-heavy, four-legged animals, such as the large, fully quadrupedal Jurassic sauropods Diplodocus and Apatosaurus.
The team found that these linked trends in size, body shape and weight distribution did not end with the evolution of fully quadrupedal sauropods. In the Cretaceous period -- the last of the three ages of the dinosaurs -- many earlier sauropod groups dwindled. In their place, a new and extremely large type of sauropod known as titanosaurs evolved, including the truly massive Argentinosaurus and Dreadnoughtus, among the largest known animals ever to have lived.
The team's computer models suggest that in addition to their size, the titanosaurs evolved the most extreme 'front heavy' body shape of all sauropods, as a result of their extremely long necks.
Dr Bates said: "As a result of devising these models we were able to ascertain that the relative size of sauropods' necks increased gradually over time, leading to animals that were increasingly more front-heavy relative to their ancestors."
Dr Philip Mannion from Imperial College London, a collaborator in the research, added: "These innovations in body shape might have been key to the success of titanosaurs, which were the only sauropod dinosaurs to survive until the end-Cretaceous mass extinction, 66 million years ago."
Dr Vivian Allen from the Royal Veterinary College London, who also collaborated in the research, added: "What's important to remember about studies like this is that there is a very high degree of uncertainty about exactly how these animals were put together. While we have good skeletons for many of them, it's difficult to be sure how much meat there was around each of the bones. We have built this uncertainly into our models, ranging each body part from emaciated to borderline obesity, and even using these extremes we still find these solid, trending changes in body proportions over sauropod evolution."
A survey of a major oil and natural gas-producing region in Western Canada suggests a link between hydraulic fracturing or "fracking" and induced earthquakes in the region, according to a new report published online in the journal Seismological Research Letters.
The study's findings differ from those reported from oil and gas fields in the central United States, where fracking is not considered to be the main cause of a sharp rise in induced seismicity in the region. Instead, the proliferation of hundreds of small earthquakes in that part of the U.S. is thought to be caused primarily by massive amounts of wastewater injected back into the ground after oil and gas recovery.
The SRL study does not examine why induced seismicity would be linked to different processes in the central U.S. and western Canada. However, some oil and gas fields in the U.S., especially Oklahoma, use "very large amounts of water" in their operations, leading to much more wastewater disposal than in Canadian operations, said Gail M. Atkinson of Western University.
It is possible that massive wastewater disposal in the U.S. is "masking another signal" of induced seismicity caused by fracking, Atkinson said. "So we're not entirely sure that there isn't more seismicity in the central U.S. from hydraulic fracturing than is widely recognized."
The fracking process uses high-pressure injections of fluid to break apart rock and release trapped oil and natural gas. Both fracking and wastewater injections can increase the fluid pressure in the natural pores and fractures in rock, or change the state of stress on existing faults, to produce earthquakes.
The Western Canada Sedimentary Basin (WCSB) contains one of the world's largest oil and gas reserves, and is dotted with thousands of fracking wells drilled in multi-stage horizontal operations. Atkinson and her colleagues compared the relationship of 12,289 fracking wells and 1236 wastewater disposal wells to magnitude 3 or larger earthquakes in an area of 454,000 square kilometers near the border between Alberta and British Columbia, between 1985 and 2015.
The researchers performed statistical analyses to determine which earthquakes were most likely to be related to hydraulic fracturing, given their location and timing. The analyses identified earthquakes as being related to fracking if they took place close to a well and within a time window spanning the start of fracking to three months after its completion, and if other causes, such as wastewater disposal, were not involved.
Atkinson and colleagues found 39 hydraulic fracturing wells (0.3% of the total of fracking wells studied), and 17 wastewater disposal wells (1% of the disposal wells studied) that could be linked to earthquakes of magnitude 3 or larger.
While these percentages sound small, Atkinson pointed out that thousands of hydraulic fracturing wells are being drilled every year in the WCSB, increasing the likelihood of earthquake activity. "We haven't had a large earthquake near vulnerable infrastructure yet," she said, "but I think it's really just a matter of time before we start seeing damage coming out of this."
The study also confirmed that in the last few years nearly all the region's overall seismicity of magnitude 3 or larger has been induced by human activity. More than 60% of these quakes are linked to hydraulic fracture, about 30-35% come from disposal wells, and only 5 to 10% of the earthquakes have a natural tectonic origin, Atkinson said.
Atkinson said the new numbers could be used to recalculate the seismic hazard for the region, which could impact everything from building codes to safety assessments of critical infrastructure such as dams and bridges. "Everything has been designed and assessed in terms of earthquake hazard in the past, considering the natural hazard," she said. "And now we've fundamentally changed that, and so our seismic hazard picture has changed."
The researchers were also surprised to find that their data showed no relationship between the volume of fluid injected at a hydraulic fracturing well site and the maximum magnitude of its induced earthquake.
"It had previously been believed that hydraulic fracturing couldn't trigger larger earthquakes because the fluid volumes were so small compared to that of a disposal well," Atkinson explained. "But if there isn't any relationship between the maximum magnitude and the fluid disposal, then potentially one could trigger larger events if the fluid pressures find their way to a suitably stressed fault."
Atkinson and her colleagues hope to refine their analyses to include other variables, such as information about extraction processes and the geology at individual well sites, "to help us understand why some areas seem much more prone to induced seismicity than others."
The scientists say the seismic risks associated with hydraulic fracturing could increase as oil and gas companies expand fracking's use in developing countries, which often contain dense populations and earthquake-vulnerable infrastructure.
So you think the gold in your ring or watch came from a mine in Africa or Australia? Well, think farther away. Much, much farther.
Michigan State University researchers, working with colleagues from Technical University Darmstadt in Germany, are zeroing in on the answer to one of science's most puzzling questions: Where did heavy elements, such as gold, originate?
Currently there are two candidates, neither of which are located on Earth -- a supernova, a massive star that, in its old age, collapsed and then catastrophically exploded under its own weight; or a neutron-star merger, in which two of these small yet incredibly massive stars come together and spew out huge amounts of stellar debris.
In a recently published paper in the journal Physical Review Letters, the researchers detail how they are using computer models to come closer to an answer.
"At this time, no one knows the answer," said Witold Nazarewicz, a professor at the MSU-based Facility for Rare Isotope Beams and one of the co-authors of the paper. "But this work will help guide future experiments and theoretical developments."
By using existing data, often obtained by means of high-performance computing, the researchers were able to simulate production of heavy elements in both supernovae and neutron-star mergers.
"Our work shows regions of elements where the models provide a good prediction," said Nazarewicz, a Hannah Distinguished Professor of Physics who also serves as FRIB's chief scientist. "What we can do is identify the critical areas where future experiments, which will be conducted at FRIB, will work to reduce uncertainties of nuclear models."
Other researchers included Dirk Martin and Almudena Arcones from Technical University Darmstadt and Erik Olsen of MSU.
MSU is establishing FRIB as a new scientific user facility for the Office of Nuclear Physics in the U.S. Department of Energy Office of Science.