A juvenile Orobates pabsti, a reptile-like four-legged amphibian. Philip Anderson of UMass Amherst and colleagues examined images of 89 fossils of early tetrapods and their fish-like forebears ranging in age from about 400 to 300 million years old. The pictured specimen is from the Museum Der Natur in Gotha, Germany. (Credit: Thomas Martens, Stiftung Schloss Friedenstein Gotha, Germany)
Scientists studying how early land vertebrates evolved from fishes long thought that the animals developed legs for moving around on land well before their feeding systems and dietary habits changed enough to let them eat a land-based diet, but strong evidence was lacking. Now, for the first time fossil jaw measurements by Philip Anderson at the University of Massachusetts Amherst and others have tested and statistically confirmed this lag.
“This pattern had been hypothesized previously, but not really tested. Now we’ve done that,” Anderson says. He and his team found that the mechanical properties of tetrapod jaws did not show significant adaptations to land-based feeding until some 40 to 80 million years after the four-legged creatures initially came out of the water. Until then, tetrapod jaws were still very fish-like, even though their owners had weight-bearing limbs and the ability to walk on land. Anderson says this finding suggests tetrapods may have shown a limited variety of feeding strategies in the early phases of their evolution on land.
“What it took to really initiate evolutionary changes in the jaw system was for these animals to start eating plants,” he says. For the study, published in an early online edition of the journal Integrative and Comparative Biology, Anderson and researchers Matt Friedman of the University of Oxford and Marcello Ruta of the University of Lincoln, U.K., examined images of 89 fossils of early tetrapods and their fish-like forebears. The fossils ranged in age from about 400 to 300 million years old. Anderson and his team were interested in how the jaws of these fossilized animals differed through time.
They used 10 biomechanical metrics to describe jaw differences. One of these, called mechanical advantage, measured how much force an animal can transfer to its bite. Anderson points out that while fossils can’t tell you what an animal actually ate, scientists can infer potential feeding behavior from fossilized evidence of biomechanical tools like jaws. The researchers compared jaw features from the fossil record and calculated the rates at which jaws evolved.
“The basic result was that it took a while for these animals to adapt their jaws for a land-based diet,” Anderson says. “They stayed essentially fish-like for a long time.”
It turns out that just moving into a new environment is not always enough to trigger functional adaptations. In their paper, the authors say the results may be explained by an earlier hypothesis: A shift from gilled to lung breathing in later tetrapod groups was necessary before they could devote their jaw structure to eating plants.
Anderson says the statistical methods they developed for this work could be used in future studies of more subtle biomechanical patterns in fossil animals that may not be initially clear.
Note : The above story is reprinted from materials provided by University of Massachusetts Amherst.
The Finnish Meteorological Institute has updated its estimates concerning the impact of rising sea levels on the Finnish coast. Post-glacial rebound and changes in Earth’s gravity field protect the Finnish coast against rising sea levels, especially in the Gulf of Bothnia. In the Gulf of Finland, the sea level is starting to rise.
The rise in ocean levels varies regionally
Global warming raises ocean levels at an accelerating pace, currently on average about three millimetres per year. The reasons for this are the thermal expansion of sea water and the melting of glaciers. It is estimated that by the end of this century, ocean levels will rise at least about 20 centimetres. The highest estimates are nearly two metres.
There is, however, great regional variation in the rise, for reasons such as the uneven warming of seas, changes in Earth’s gravity field, and changes in the circulation of seas. The Finnish Meteorological Institute has used the latest scientific publications to estimate the impact of these regional factors on the Finnish coast.
As glaciers melt, mass will shift from continents into seas. In consequence, Earth’s gravity field and the height of Earth’s crust will be altered. The mass of continental glaciers will no longer attract sea water as strongly as before. In addition, Earth’s crust will rise under the lighter glacier. For this reason, the rise in the sea level will be minor near the melting glacier, whereas the rise will be felt more acutely further away from the glacier.In consequence, the melting of the continental glacier in Greenland will have a fairly small impact on the Finnish coast. The regional rise in Finland will remain below the global average.
The characteristics of the Baltic Sea affect the Finnish coast
In addition to the regional rise in ocean levels, local events in the Baltic Sea affect the sea level changes on the Finnish coast. In Finland, the uplift of the land after the last glacial period is still 4-10 millimetres per year. Moreover, climate models predict stronger western winds, which will push water into the Baltic Sea through the Danish straits and water will accumulate against the Finnish coast.
So far, post-glacial rebound has offset the rise in sea level in Finland, but the situation is gradually changing on the southern coast. It is estimated that the sea level will start to rise in the Gulf of Finland. In the Gulf of Bothnia, the uplift is still likely to even out the sea level rise in the coming decades.
If the highest projections come to pass, the sea level will rise everywhere on the Finnish coast: by as much as 90 centimetres in the Gulf of Finland by the end of the century, by 65 cm in the Bothnian Sea and by about 30 cm in the Bay of Bothnia.
The current estimate concerns the change in the average sea level in the long term. In addition, the impact of waves and other changes in the short-term variation of the sea level must be taken into account in building and other activities on the coast. In the near future, the Finnish Meteorological Institute will update its estimates of the lowest recommended building heights, where these factors will also be considered.
Note : The above story is reprinted from materials provided by Finnish Meteorological Institute.
New study supports theory that Earth’s earliest crust was folded back into its mantle and returned to the surface in volcanoes
An international team of researchers, including Scripps Institution of Oceanography, UC San Diego, geochemist James Day, has found new evidence that material contained in oceanic lava flows originated in Earth’s ancient Archean crust. These findings support the theory that much of the Earth’s original crust has been recycled by the process of subduction, helping to explain how the Earth has formed and changed over time.
The Archean geologic eon, Earth’s second oldest, dating from 3.8 to 2.5 billion years ago, is the source of the oldest exposed rock formations on the planet’s surface. (Archean rocks are known from Greenland, the Canadian Shield, the Baltic Shield, Scotland, India, Brazil, western Australia, and southern Africa.) Although the first continents were formed during the Archean eon, rock of this age makes up only around seven percent of the world’s current crust.
“Our new results are important because they provide strong evidence not only to tie materials that were once on Earth’s surface to an entire cycle of subduction, storage in the mantle, and return to the surface as lavas, but they also place a firm time constraint on when plate tectonics began; no later than 2.5 billion years ago,” said Day. “This is because mass independent sulfur signatures have only been shown to occur in the atmosphere during periods of low oxygenation prior to the rise of oxygen-exhaling organisms.”
The new study, which will be published in the April 24 issue of the journal Nature, adds further support to the theory that most of the Archean crust was subducted or folded back into the Earth’s mantle, evidence of which is seen in the presence of specific sulfur isotopes found in some oceanic lava flows.
According to the researchers, because terrestrial independently fractionated (MIF) sulfur-isotope isotope signatures were generated exclusively through atmospheric photochemical reactions until about 2.5 billion years ago, material containing such isotopes must have originated in the Archean crust. In the new study, the researchers found MIF sulfur-isotope signatures in olivine-hosted sulfides from relatively young (20-million-year-old) ocean island basalts (OIB) from Mangaia, Cook Islands (Polynesia), providing evidence that the mantle is the only possible source of the ancient Archean materials found in the Mangaia lavas.
“The discovery of MIF-S isotope in these young oceanic lavas suggests that sulfur—likely derived from the hydrothermally-altered oceanic crust—was subducted into the mantle more than 2.5 billion years ago and recycled into the mantle source of the Mangaia lavas,” said Rita Cabral, the study’s primary author and a graduate student in Boston University’s Department of Earth and Environment.
The data also complement evidence for sulfur recycling of ancient sedimentary materials to the subcontinental lithospheric mantle previously identified in diamond inclusions.
Other study co-authors are Matthew G. Jackson of Boston University; Estelle F. Rose-Koga and Kenneth T. Koga of Université Blaise Pascal in Clermont-Ferrand, France; Martin J. Whitehouse of the Swedish Museum of Natural History and Stockholm University, Stockholm, Sweden; Michael A. Antonelli and James Farquhar of the University of Maryland; and Erik H. Hauri of the Carnegie Institution of Washington in Washington, D.C.
Note : The above story is reprinted from materials provided by University of California
Forecasting volcanic eruptions with success is heavily dependent on recognizing well-established patterns of pre-eruption unrest in the monitoring data. But in order to develop better monitoring procedures, it is also crucial to understand volcanic eruptions that deviate from these patterns.
New research from a team led by Carnegie’s Diana Roman retrospectively documented and analyzed the period immediately preceding the 2009 eruption of the Redoubt volcano in Alaska, which was characterized by an abnormally long period of pre-eruption seismic activity that’s normally associated with short-term warnings of eruption. Their work is published today by Earth and Planetary Science Letters.
Well-established pre-eruption patterns can include a gradual increase in the rate of seismic activity, a progressive alteration in the type of seismic activity, or a change in ratios of gas released. “But there are numerous cases of volcanic activity that in some way violated these common patterns of precursory unrest,” Roman said. “That’s why examining the unusual precursor behavior of the Redoubt eruption is so enlightening.”
About six to seven months before the March 2009 eruption, Redoubt began to experience long-period seismic events, as well as shallow volcanic tremors, which intensified into a sustained tremor over the next several months. Immediately following this last development, shallow, short-period earthquakes were observed at an increased rate below the summit. In the 48 hours prior to eruption both deep and shallow earthquakes were recorded.
This behavior was unusual because precursor observations usually involve a transition from short-period to long-period seismic activity, not the other way around. What’s more, seismic tremor is usually seen as a short-term warning, not something that happens months in advance. However, these same precursors were also observed during the 1989-90 Redoubt eruption, thus indicating that the unusual seismic pattern reflects some unique aspect of the volcano’s magma system.
Advanced analysis of the seismic activity taking place under the volcano allowed Roman and her team to understand the changes taking place before, during, and after eruption. Their results show that the eruption was likely preceded by a protracted period of slow magma ascent, followed by a short period of rapidly increasing pressure beneath Redoubt.
Elucidating the magma processes causing these unusual precursor events could help scientists to hone their seismic forecasting, rather than just relying on the same forecasting tools they’re currently using, ones that are not able to detect anomalies.
For example, using current techniques, the forecasts prior to Redoubt’s 2009 eruption wavered over a period of five months, back and forth between eruption being likely within a few weeks to within a few days. If the analytical techniques used by Roman and her team had been taken into consideration, the early risk escalations might not have been issued.
“Our work shows the importance of clarifying the underlying processes driving anomalous volcanic activity. This will allow us to respond to subtle signals and increase confidence in making our forecasts.” Roman said.
Note : The above story is reprinted from materials provided by Carnegie Institution.
Geologists at summit of Kima’Kho volcano look to the east and south across the Kawdy plateau. The plateau hosts at least six other tuyas. (Credit: UBC Science)
Deposits left by the eruption of a subglacial volcano, or tuya, 1.8 million years ago could hold the secret to more accurate palaeo-glacial and climate models, according to new research by University of British Columbia geoscientists.
The detailed mapping and sampling of the partially eroded Kima’ Kho tuya in northern British Columbia, Canada shows that the ancient regional ice sheet through which the volcano erupted was twice as thick as previously estimated.
Subglacial eruptions generate distinctive deposits indicating whether they were deposited below or above the waterline of the englacial lakes–much like the rings left on the inside of a bath tub. The transitions from subaqueous from subaerial deposits are called passage zones and define the high stands of englacial lakes. The depth and volume of water in these ephemeral lakes, in turn, gives researchers an accurate measure of the minimum palaeo-ice thicknesses at the time of eruption.
“At Kima’Kho, we were able to map a passage zone in pyroclastic deposits left by the earliest explosive phase of eruption, allowing for more accurate forensic recovery of paleo-lake levels through time and better estimates of paleo-ice thicknesses,” says UBC volcanologist James K Russell, lead author on the paper published this week in Nature Communications.
“Applying the same technique to other subglacial volcanos will provide new constraints on paleoclimate models that consider the extents and timing of planetary glaciations.”
While relatively rare globally, tuyas are common throughout Iceland, British Columbia, Oregon, and beneath the Antarctic ice-sheets. Kima’Kho tuya forms a high relief structure covering 28 square kilometres rising 1,946 metres above sea level on the Kawdy Plateau near Dease Lake. The plateau hosts six other tuyas.
“We hope our discovery encourages more researchers to seek out pyroclastic passage zones,” says Lucy Porritt, a Marie Curie Research Fellow at UBC and University of Bristol. “With more detailed mapping of glaciovolcanic sequences, and the recognition of the importance of these often abrupt changes in depositional environment, our understanding of glaciovolcanic eruptions and the hazards they pose can only be advanced.”
Note : The above story is reprinted from materials provided by University of British Columbia, via EurekAlert!, a service of AAAS.
Ten million years after the mass extinction, members of the archosaur reptiles — such as the 10-foot (3 meter) long Asilisaurus pictured — had more restricted geographic ranges compared to the communities of four-legged animals that existed before the extinction. (Credit: Marlene Donnelly/Field Museum of Natural History)
Many scientists have thought that dinosaur predecessors missed the race to fill habitats emptied when nine out of 10 species disappeared during Earth’s largest mass extinction, approximately 252 million years ago. The thinking was based on fossil records from sites in South Africa and southwest Russia.
It turns out that scientists may have been looking for the starting line in the wrong places.
Newly discovered fossils from 10 million years after the mass extinction reveal a lineage of animals thought to have led to dinosaurs taking hold in Tanzania and Zambia in the mid-Triassic period, many millions of years before dinosaur relatives were seen in the fossil record elsewhere on Earth.
“The fossil record from the Karoo of South Africa remains a good representation of four-legged land animals across southern Pangea before the extinction event. But after the event animals weren’t as uniformly and widely distributed as before. We had to go looking in some fairly unorthodox places,” said Christian Sidor, University of Washington professor of biology. He’s lead author of a paper appearing the week of April 29 in the early edition of the Proceedings of the National Academy of Sciences.
The new insights come from seven fossil-hunting expeditions since 2003 in Tanzania, Zambia and Antarctica, funded by the National Geographic Society and National Science Foundation, along with work combing through existing fossil collections. The researchers created two “snapshots” of four legged-animals about 5 million years before and again about 10 million years after the extinction event at the end of the Permian period.
Prior to the extinction event, for example, the pig-sized Dicynodon — said to resemble a fat lizard with a short tail and turtle’s head — was a dominant plant-eating species across southern Pangea. Pangea is the name given to the landmass when all the world’s continents were joined together. Southern Pangea was made up of what is today Africa, South America, Antarctica, Australia and India. After the mass extinction at the end of the Permian, Dicynodon disappeared and other related species were so greatly decreased that newly emerging herbivores could suddenly compete with them.
“Groups that did well before the extinction didn’t necessarily do well afterward,” Sidor said. “What we call evolutionary incumbency was fundamentally reset.”
The snapshot 10 million years after the extinction event reveals, among other things, that archosaurs were in Tanzanian and Zambian basins, but not distributed across all of southern Pangea as had been the pattern for four-legged animals prior to the extinction. Archosaurs are the group of reptiles that includes crocodiles, dinosaurs, birds and a variety of extinct forms. They are of interest because it is thought they led to animals like Asilisaurus, a dinosaur-like animal, and Nyasasaurus parringtoni, a dog-sized creature with a five-foot tail that scientists in December 2012 announced could be the earliest dinosaur, or else the closest relative found so far.
“Early archosaurs being found mainly in Tanzania is an example of how fragmented communities became after the extinction event,” Sidor said. And the co-authors write: “These findings suggest that . . . archosaur diversification was more intimately related to recovery from the end-Permian mass extinction than previously suspected.”
A new framework for analyzing biogeographic patterns from species distributions, developed by co-author Daril Vilhena, a UW biology graduate student, provided a way to discern the complex recovery, Sidor said.
It revealed that before the extinction event 35 percent of four-legged species were found in two or more of the five areas studied, with some species having ranges that stretched 1,600 miles (2,600 kilometers), encompassing the Tanzanian and South African basins. Ten million years after the extinction event, the authors say there was clear geographic clustering and just 7 percent of species were found in two or more regions.
The techniques — new ways to statistically consider how connected or isolated species are from each other — could be useful for other paleontologists and modern day biogeographers, Sidor said.
In the early 2000s Sidor and some of his co-authors started putting together expeditions to collect fossils from sites in Tanzania that hadn’t been visited since the 1960s and in Zambia where there’d been little work since the ’80s. Two expeditions to Antarctica provided additional materials, as did long-term efforts to examine museum-held fossils that had not been fully documented or named
Other co-authors from the UW are graduate students Adam Huttenlocker and Brandon Peecook, post-doctoral researcher Sterling Nesbitt and research associate Linda Tsuji; Kenneth Angielczyk of the Field Museum of Natural History in Chicago; Roger Smith, of the Iziko South African Museum in Cape Town; and Sébastien Steyer from the National Museum of Natural History in Paris.
Funding was also received from the Evolving Earth Foundation, the Grainger Foundation, the Field Museum/IDP Inc. African Partners Program and the National Research Council of South Africa.
Note : The above story is reprinted from materials provided by University of Washington. The original article was written by Sandra Hines.
The Geoblock program is integrated software for 2D/3D modeling, computational geometry and visualization of spatial datasets. The program can be used in Earth sciences particularly in such fields as survey, geology and mining modeling, ore reserve estimations and prediction of mineral liberation under grinding and mineral processing operations.
The contents of the Geoblock program are subject to the Mozilla Public License Version 1.1. This software delivers with open source codes as an integrated system for users and developers. You can use it free of charge for non-commercial use.To order the full installation on CD with the latest stable version and additional documentation
Features
The program supports several spatial dataset types: Drillholes, Points, Polygons, TINs, Solids, Grids and Meshes. Combined datasets can be organized into project collections and displayed inside Map Window of the program as a combination of contours, wireframe or block models simultaneously.
The databases can be stored in various relational formats: Paradox, Interbase, MS Access and Oracle. Spatial data and graphical objects can be exported/imported to DXF (AutoCAD), MIF/MID (MapInfo), GRD (Surfer, ArcInfo) and other formats.
There are a set of routines for grid and mesh generation in 2D and 3D. For example procedures for exploration and processing drillhole data include:
·Drillhole data analysis and data transformations.
·Compositing drillhole samples inside benches or horizons
·Calculation of sample XYZ coordinates in drillholes and exploration lines
·Mineral liberation and prediction of ore dressing parameters
Interpolation:
·Inverse Distance
·Linear by TINs
·Closest Point
As optional features there are next methods of interpolation:
·Kriging
·Natural Neighbors
·Polynomial Regression
Several spatial models can be visualized simultaneously in Map window using project manager. Constructed grids and block models could be used for open pit optimization and mine planning. Deposit reserves for any ore type or sort can be calculated with different methods using spatial computer models.
New research reveals that Microraptor, a small flying dinosaur, was a complete hunter — able to swoop down and pick up fish. (Credit: Image courtesy of University of Alberta)
University of Alberta-led research reveals that Microraptor, a small flying dinosaur was a complete hunter, able to swoop down and pickup fish as well as its previously known prey of birds and tree dwelling mammals.U of A paleontology graduate student Scott Persons says new evidence of Microrpator’s hunting ability came from fossilized remains in China. “We were very fortunate that this Microraptor was found in volcanic ash and its stomach content of fish was easily identified.”
Prior to this, paleontologists believed microraptors which were about the size of a modern day hawk, lived in trees where they preyed exclusively on small birds and mammals about the size of squirrels.
“Now we know that Microraptor operated in varied terrain and had a varied diet,” said Persons. “It took advantage of a variety of prey in the wet, forested environment that was China during the early Cretaceous period, 120 million years ago.”
Further analysis of the fossil revealed that its teeth were adapted to catching slippery, wiggling prey like fish. Dinosaur researchers have established that most meat eaters had teeth with serrations on both sides which like a steak knife helped the predator saw through meat.
But the Microraptor’s teeth are serrated on just one side and its teeth are angled forwards.
“Microraptor seems adapted to impale fish on its teeth. With reduced serrations the prey wouldn’t tear itself apart while it struggled,” said Persons. “Microraptor could simply raise its head back, the fish would slip off the teeth and be swallowed whole, no fuss no muss.”
Persons likens the Microraptor’s wing configuration to a bi-plane. “It had long feathers on its forearms, hind legs and tail,” said Persons. “It was capable of short, controlled flights.”
This is the first evidence of a flying raptor, a member of the Dromaeosaur family of dinosaurs to successfully prey on fish.
Note : The above story is reprinted from materials provided by University of Alberta, via EurekAlert!, a service of AAAS.
This artist’s view depicts the different layers of the Earth and their representative temperatures: crust, upper and lower mantle (brown to red), liquid outer core (orange) and solid inner core (yellow). The pressure at the border between the liquid and the solid core (highlighted) is 3.3 million atmospheres, with a temperature now confirmed as 6000 degrees Celsius. (Credit: ESRF)
Scientists have determined the temperature near the Earth’s centre to be 6000 degrees Celsius, 1000 degrees hotter than in a previous experiment run 20 years ago. These measurements confirm geophysical models that the temperature difference between the solid core and the mantle above, must be at least 1500 degrees to explain why the Earth has a magnetic field. The scientists were even able to establish why the earlier experiment had produced a lower temperature figure.The results are published on 26 April 2013 in Science.
The research team was led by Agnès Dewaele from the French national technological research organization CEA, alongside members of the French National Center for Scientific Research CNRS and the European Synchrotron Radiation Facility ESRF in Grenoble (France).
The Earth’s core consists mainly of a sphere of liquid iron at temperatures above 4000 degrees and pressures of more than 1.3 million atmospheres. Under these conditions, iron is as liquid as the water in the oceans. It is only at the very centre of the Earth, where pressure and temperature rise even higher, that the liquid iron solidifies. Analysis of earthquake-triggered seismic waves passing through the Earth, tells us the thickness of the solid and liquid cores, and even how the pressure in the Earth increases with depth. However these waves do not provide information on temperature, which has an important influence on the movement of material within the liquid core and the solid mantle above. Indeed the temperature difference between the mantle and the core is the main driver of large-scale thermal movements, which together with the Earth’s rotation, act like a dynamo generating the Earth’s magnetic field. The temperature profile through the Earth’s interior also underpins geophysical models that explain the creation and intense activity of hot-spot volcanoes like the Hawaiian Islands or La Réunion.
To generate an accurate picture of the temperature profile within the Earth’s centre, scientists can look at the melting point of iron at different pressures in the laboratory, using a diamond anvil cell to compress speck-sized samples to pressures of several million atmospheres, and powerful laser beams to heat them to 4000 or even 5000 degrees Celsius.”In practice, many experimental challenges have to be met,” explains Agnès Dewaele from CEA, “as the iron sample has to be insulated thermally and also must not be allowed to chemically react with its environment. Even if a sample reaches the extreme temperatures and pressures at the centre of the Earth, it will only do so for a matter of seconds. In this short timeframe it is extremely difficult to determine whether it has started to melt or is still solid.”
This is where X-rays come into play. “We have developed a new technique where an intense beam of X-rays from the synchrotron can probe a sample and deduce whether it is solid, liquid or partially molten within as little as a second, using a process known diffraction,” says Mohamed Mezouar from the ESRF, “and this is short enough to keep temperature and pressure constant, and at the same time avoid any chemical reactions.”
The scientists determined experimentally the melting point of iron up to 4800 degrees Celsius and 2.2 million atmospheres pressure, and then used an extrapolation method to determine that at 3.3 million atmospheres, the pressure at the border between liquid and solid core, the temperature would be 6000 +/- 500 degrees. This extrapolated value could slightly change if iron undergoes an unknown phase transition between the measured and the extrapolated values.
When the scientists scanned across the area of pressures and temperatures, they observed why Reinhard Boehler, then at the MPI for Chemistry in Mainz (Germany), had in 1993 published values about 1000 degrees lower. Starting at 2400 degrees, recrystallization effects appear on the surface of the iron samples, leading to dynamic changes of the solid iron’s crystalline structure. The experiment twenty years ago used an optical technique to determine whether the samples were solid or molten, and it is highly probable that the observation of recrystallization at the surface was interpreted as melting.
“We are of course very satisfied that our experiment validated today’s best theories on heat transfer from the Earth’s core and the generation of the Earth’s magnetic field. I am hopeful that in the not-so-distant future, we can reproduce in our laboratories, and investigate with synchrotron X-rays, every state of matter inside the Earth,” concludes Agnès Dewaele.
Note : The above story is reprinted from materials provided by European Synchrotron Radiation Facility.
Stromatolites or stromatoliths are layered accretionary structures formed in shallow water by the trapping, binding and cementation of sedimentary grains by biofilms of microorganisms, especially cyanobacteria (commonly known as blue-green algae). Stromatolites provide some of the most ancient records of life on Earth by fossil remains which date back more than 3.5 billion years ago.
Morphology
A variety of stromatolite morphologies exist including conical, stratiform, branching, domal, and columnar
types. Stromatolites occur widely in the fossil record of the Precambrian, but are rare today. Very few ancient stromatolites contain fossilized microbes. While features of some stromatolites are suggestive of biological activity, others possess features that are more consistent with abiotic (non-organic) precipitation. Finding reliable ways to distinguish between biologically formed and abiotic (non-biological) stromatolites is an active area of research in geology.
Fossil record
Stromatolites were much more abundant on the planet in Precambrian times. While older, Archean fossil
remains are presumed to be colonies of cyanobacteria, younger (that is, Proterozoic) fossils may be primordial forms of the eukaryote chlorophytes (that is, green algae). One genus of stromatolite very common in the geologic record is Collenia. The earliest stromatolite of confirmed microbial origin dates to 2.724 billion years ago. A 2009 discovery provides strong evidence of microbial stromatolites extending as far back as 3.450 billion years ago.
Stromatolites are a major constituent of the fossil record for about the first 3.5 billion years of life on earth, peaking about 1.25 billion years ago. They subsequently declined in abundance and diversity, which by the start of the Cambrian had fallen to 20% of their peak. The most widely supported explanation is that stromatolite builders fell victims to grazing creatures (the Cambrian substrate revolution), implying that sufficiently complex organisms were common over 1 billion years ago.
Stromatolites in the Hoyt Limestone (Cambrian) exposed at Lester Park, near Saratoga Springs, New York.
The connection between grazer and stromatolite abundance is well documented in the younger Ordovician evolutionary radiation; stromatolite abundance also increased after the end-Ordovician and end-Permian extinctions decimated marine animals, falling back to earlier levels as marine animals recovered. Fluctuations in metazoan population and diversity may not have been the only factor in the reduction in stromatolite abundance. Factors such as the chemistry of the environment may have been responsible for changes.
While prokaryotic cyanobacteria themselves reproduce asexually through cell division, they were instrumental in priming the environment for the evolutionary development of more complex eukaryotic organisms. Cyanobacteria (as well as extremophile Gammaproteobacteria) are thought to be largely responsible for increasing the amount of oxygen in the primeval earth’s atmosphere through their continuing photosynthesis. Cyanobacteria use water, carbon dioxide, and sunlight to create their food. A layer of mucus often forms over mats of cyanobacterial cells. In modern microbial mats, debris from the surrounding habitat can become trapped within the mucus, which can be cemented together by the calcium carbonate to grow thin laminations of limestone. These laminations can accrete over time, resulting in the banded pattern common to stromatolites. The domal morphology of biological stromatolites is the result of the vertical growth necessary for the continued infiltration of sunlight to the organisms for photosynthesis. Layered spherical growth structures termed oncolites are similar to stromatolites and are also known from the fossil record. Thrombolites are poorly laminated or non-laminated clotted structures formed by cyanobacteria common in the fossil record and in modern sediments.
The Zebra River Canyon area of the Kubis platform in the deeply dissected Zaris Mountains of south western Namibia provides an extremely well exposed example of the thrombolite-stromatolite-metazoan reefs that developed during the Proterozoic period, the stromatolites here being better developed in updip locations under conditions of higher current velocities and greater sediment influx.
Modern occurrence
Modern stromatolites are mostly found in hypersaline lakes and marine lagoons where extreme conditions due to high saline levels exclude animal grazing. One such location is Hamelin Pool Marine Nature Reserve, Shark Bay in Western Australia where excellent specimens are observed today, and another is Lagoa Salgada, state of Rio Grande do Norte, Brazil, where modern stromatolites can be observed as bioherm
Stromatolites at Lake Thetis, Western Australia
(domal type) and beds. Inland stromatolites can also be found in saline waters in Cuatro Ciénegas, a unique ecosystem in the Mexican desert, and in Lake Alchichica, a maar lake in Mexico’s Oriental Basin. The only open marine environment where modern stromatolites are known to prosper is the Exuma Cays in the Bahamas.
Very recently, the fifth Chlorophyll: Chlorophyll f was discovered by Dr. Min Chen from stromatolites in Shark Bay.
Modern freshwater stromatolites
Laguna Bacalar in Mexico’s southern Yucatán Peninsula in the state of Quintana Roo, has an extensive formation of living giant microbialites (that is, stromatolites or thrombolites). The microbialite bed is over 10 km (6.2 mi) long with a vertical rise of several meters in some areas. These may be the largest sized living freshwater microbialites, or any organism, on Earth.
A little further to the south, a 1.5 km stretch of reef-forming stromatolites (primarily of the Scytonema genus)
Microbialite towers at Pavilion Lake, British Columbia
occurs in Chetumal Bay in Belize, just south of the mouth of the Rio Hondo and the Mexican border.
Freshwater stromatolites are found in Lake Salda in southern Turkey. The waters are rich in magnesium and the stromatolite structures are made of hydromagnesite.
Another pair of instances of freshwater stromatolites are at Pavilion and Kelly Lakes in British Columbia, Canada. Pavilion Lake has the largest known freshwater stromatolites and has been researched by NASA as part of xenobiology research. NASA, the Canadian Space Agency and numerous universities from around the world are collaborating on a project centered around studying microbialite life in the lakes. Called the “Pavilion Lake Research Project” (PLRP) its aim is to study what conditions on the lakes’ bottoms are most likely to harbor life and develop a better hypothesis on how environmental factors effect microbiolite life. The end goal of the project is to better understand what condition would be more likely to harbor life on other planets. There is a citizen science project online called “MAPPER” where anyone can help sort through thousands of photos of the lake bottoms and tag microbiolites, algae and other lake bed features.
Microbialites have been discovered in an open pit pond at an abandoned asbestos mine near Clinton Creek, Yukon, Canada. These microbialites are extremely young and presumably began forming soon after the mine closed in 1978. The combination of a low sedimentation rate, high calcification rate, and low microbial growth rate appears to result in the formation of these microbialites. Microbialites at an historic mine site demonstrates that an anthropogenically constructed environment can foster microbial carbonate formation. This has implications for creating artificial environments for building modern microbialites including stromatolites.
A very rare type of non-lake dwelling stromatolite lives in the Nettle Cave at Jenolan Caves, NSW, Australia. The cyanobacteria live on the surface of the limestone, and are sustained by the calcium rich dripping water, which allows them to grow toward the two open ends of the cave which provide light.
Note: The above story is reprinted from materials provided by Wikipedia
Scientists have long believed that lava erupted from certain oceanic volcanoes contains materials from the early Earth’s crust. But decisive evidence for this phenomenon has proven elusive. New research from a team including Carnegie’s Erik Hauri demonstrates that oceanic volcanic rocks contain samples of recycled crust dating back to the Archean era 2.5 billion years ago. Their work is published in Nature.
Oceanic crust sinks into Earth’s mantle at so-called subduction zones, where two plates come together. Much of what happens to the crust during this journey is unknown. Model-dependent studies for how long subducted material can exist in the mantle are uncertain and evidence of very old crust returning to Earth’s surface via upwellings of magma has not been found until now.
The research team studied volcanic rocks from the island of Mangaia in Polynesia’s Cook Islands that contain iron sulfide inclusions within crystals. In-depth analysis of the chemical makeup of these samples yielded interesting results.
The research focused on isotopes of the element sulfur. (Isotopes are atoms of the same element with different numbers of neutrons.) The measurements, conducted by graduate student Rita Cabral, looked at three of the four naturally occurring isotopes of sulfur–isotopic masses 32, 33, and 34. The sulfur-33 isotopes showed evidence of a chemical interaction with UV radiation that stopped occurring in Earth’s atmosphere about 2.45 billion years ago. It stopped after the Great Oxidation Event, a point in time when Earth’s atmospheric oxygen levels skyrocketed as a consequence of oxygen-producing photosynthetic microbes. Prior to the Great Oxidation Event, the atmosphere lacked ozone. But once ozone was introduced, it started to absorb UV and shut down the process.
This indicates that the sulfur comes from a deep mantle reservoir containing crustal material subducted before the Great Oxidation Event and preserved for over half the age of Earth.
“These measurements place the first firm age estimates of recycled material in oceanic hotspots,” Hauri said. “They confirm the cycling of sulfur from the atmosphere and oceans into mantle and ultimately back to the surface,” Hauri said.
Note: The above story is reprinted from materials provided by Carnegie Institution.
Life on Earth may have originated not in warm tropical seas, but with weird tubes of ice — sometimes called “sea stalactites” — that grow downward into cold seawater near the Earth’s poles. (Credit: Rob Robbins; image archived by EarthRef.org)
Life on Earth may have originated not in warm tropical seas, but with weird tubes of ice — sometimes called “sea stalactites” — that grow downward into cold seawater near Earth’s poles, scientists are reporting. Their article on these “brinicles” appears in ACS’ journal Langmuir.Bruno Escribano and colleagues explain that scientists know surprisingly little about brinicles, which are hollow tubes of ice that can grow to several yards in length around streamers of cold seawater under pack ice. That’s because brinicles are difficult to study. The scientists set out to gather more information on the topic with an analysis of the growth process of brinicles.
They are shown to be analogous to a “chemical garden,” a standby demonstration in chemistry classes and children’s chemistry sets, in which tubes grow upward from metal salts dropped into silicate solution. But brinicles grow downward from the bottom of the ice pack.
The analysis concluded that brinicles provide an environment that could well have fostered the emergence of life on Earth billions of years ago, and could have done so on other planets. “Beyond Earth, the brinicle formation mechanism may be important in the context of planets and moons with ice-covered oceans,” the report states, citing in particular two moons of Jupiter named Ganymede and Callisto.
Note: The above story is reprinted from materials provided by American Chemical Society.
Carbonate shells of the freshwater gastropod Viviparus lentus from the Hampshire Basin, UK. Credit: Photo courtesy of Michael Hren
Nearly 34 million years ago, Earth underwent a transformation from a warm, high-carbon dioxide “greenhouse” state to a lower-CO2, variable climate similar to the modern “icehouse” world. Massive ice sheets grew across the Antarctic continent, major animal groups shifted, and ocean temperatures decreased by as much as 5 degrees.
But studies of how this drastic change affected temperatures on land have had mixed results. Some show no appreciable terrestrial climate change; others find cooling of up to 8 degrees and large changes in seasonality.
Now a group of American and British scientists have used a new chemical technique to measure the change in terrestrial temperature associated with this shift in global atmospheric CO2 concentrations.
Their results suggest a drop of as much as 10 degrees for fresh water during the warm season and 6 degrees for the atmosphere in the North Atlantic, giving further evidence that the concentration of atmospheric carbon dioxide and Earth’s surface temperature are inextricably linked.
“One of the key principles of geology is that the past is the key to the present: records of past climate inform us of how the Earth system functions,” says Michael Hren, assistant professor of chemistry and geosciences at the University of Connecticut and the study’s lead author. “By understanding past climate transitions, we can better understand the present, and predict impacts for the future.”
The transition between the Late Eocene and the Oligocene epochs (between 34 million and 33.5 million years ago) was triggered in part, the authors write in their April 22 paper in Proceedings of the National Academy of Sciences, by changes in the concentration of atmospheric CO2 that enabled ice to build up on the Antarctic continent.
Ice-sheet growth, coupled with favorable changes in Earth’s orbit, pushed the planet past a climatic tipping point and led to both the rapid buildup of a permanent ice sheet in the Antarctic and much larger changes in global climate, says Hren.
But much of what is known about this time period’s climate comes from cores drilled deep in the ocean, Hren says. There, organic and inorganic remains of ancient marine creatures retain chemical signatures of ocean temperatures when they were alive.
Now, Hren and his colleagues have used a recently-developed “clumped isotope thermometer” to examine terrestrial fossil shells from this time period. The team collected fossilized snails from the Isle of Wight, Great Britain, and looked for not just the kind and number of carbon and oxygen isotopes present, but how they were bound together.
The abundance of bonds containing heavy isotopes of both oxygen and carbon are temperature-dependent, so they can give a reliable picture of the terrestrial climate.
“The unique thing here is that we’re using isotopologues to measure the temperature that these snails experienced, and relating that to the climate during this interval of declining CO2,” Hren says.
What makes their results so important, says Hren, is that it’s further evidence that CO2 is linked not only to climate by way of the vast oceans and their temperature, but by terrestrial temperatures, too.
“It gives further evidence of the close links between atmospheric CO2 and temperature, but also shows how heterogeneous this climate change may be on land,” he adds.
Studies have shown that before this drastic cooling event, Earth’s atmosphere contained 1,000 parts per million (ppm) of CO2 or more, and by the end of the transition, it was likely lower than 600-700 ppm. Some predictions, notes Hren, suggest that Earth’s current CO2 concentrations, currently at close to 400 ppm and climbing, could increase to nearly 1,000 ppm in the next 100 years.
If that turns out to be the case, it’s likely that temperature changes on the scale of the Eocene to Oligocene could occur — but in the other direction, toward a much warmer climate that could again fundamentally alter living things on Earth.
“We are on a path to fundamentally alter our global climate state,” says Hren. “These data definitely give you pause.”
The other members of the research group are: Nathan Dale Sheldon and Kyger C. Lohmann of the University of Michigan; Stephen T. Grimes and Melanie Bugler of Plymouth University; Margaret E. Collinson of Royal Holloway University; and Jerry J. Hooker of the Natural History Museum.
Note : The above story is reprinted from materials provided by University of Connecticut.
Formula: Cu3(CO3)2(OH)2 Colour: Azure blue, blue, light blue, or dark blue; light blue in transmitted light Lustre: Vitreous Hardness: 3½ – 4 Specific Gravity: 3.77 Crystal System: Monoclinic Name: From the ancient Persian lazhward, meaning “blue”, in allusion to the color. Name changed to azurite in 1824 by Francois Sulpice Beudant. Type Locality: Chessy copper mines, Chessy-les-Mines, Villefranche, Rhône, Auvergne-Rhône-Alpes, France
Azurite is a soft, deep blue copper mineral produced by weathering of copper ore deposits. It is also known as Chessylite after the type locality at Chessy-les-Mines near Lyon, France.
The mineral, a carbonate, has been known since ancient times, and was mentioned in Pliny the Elder’s Natural History under the Greek name kuanos (κυανός: “deep blue,” root of English cyan) and the Latin name caeruleum. The blue of azurite is exceptionally deep and clear, and for that reason the mineral has tended to be associated since antiquity with the deep blue color of low-humidity desert and winter skies.
Physical Properties of Azurite
Cleavage: {011} Perfect, {100} Fair Color: Azure blue, Blue, Light blue, Dark blue. Density: 3.77 – 3.89, Average = 3.83 Diaphaneity: Transparent to subtranslucent Fracture: Brittle – Conchoidal – Very brittle fracture producing small, conchoidal fragments. Habit: Prismatic – Crystals Shaped like Slender Prisms (e.g. tourmaline). Habit: Stalactitic – Shaped like pendant columns as stalactites or stalagmites (e.g. calcite). Habit: Tabular – Form dimensions are thin in one direction. Hardness: 3.5-4 – Copper Penny-Fluorite Luminescence: Non-fluorescent. Luster: Vitreous (Glassy) Streak: light blue
Photos
Azurite, columnar aggregate of stalactites, Bisbee Arizona. Detail, size 13 x 75 x 15 cm. Part of the Rocks and Minerals display in the Royal Ontario Museum TorontoAzurite in siltstone, Malbunka mine, NT
Iron ore mine in the Hamersley region, Western Australia. (Credit: Professor K.O. Konhauser)
Researchers from the University of Tübingen have been able to show for the first time how microorganisms contributed to the formation of the world’s biggest iron ore deposits. The biggest known deposits — in South Africa and Australia — are geological formations billions of years old. They are mainly composed of iron oxides — minerals we know from the rusting process. These iron ores not only make up most of the world demand for iron — the formations also help us to better understand the evolution of the atmosphere and climate, and provide important information on the activity of microorganisms in the early history of life on Earth.
The extent to which microbes in the Earth’s ancient oceans contributed to the formation of iron deposits was previously unknown. Now an international team of researchers from the US, Canada and Germany has published new findings in the journal Nature Communications. Led by University of Tübingen geomicrobiologist Professor Andreas Kappler of the Center for Applied Geoscience, they found evidence of which microbes contributed to the formation of the iron ores, and were able to show how different metabolic processes can be distinguished in the rock formations today.
The iron in the Earth’s ancient oceans was spat out of hot springs on the seafloor as dissolved, reduced ferrous [Fe(II)] iron. But most of today’s iron ore is oxidized, ferric [Fe(III)] iron in the form of “rust minerals” — indicating that the Fe(II) was oxidized as it was deposited. The classic model for the formation of iron deposits suggested that the Fe(II) from the Earth’s core was oxidized by the oxygen produced by cyanobacteria (blue-green algae). This process can happen either chemically (as in the formation of rust) or by the action of microaerophilic iron-oxidizing bacteria.
But scientists are still debating at what point the Earth’s atmosphere contained enough oxygen (produced by cyanobacteria) to allow the formation of big iron deposits. The oldest known iron ores were deposited in the Precambrian period and are up to four billion years old (the Earth itself is estimated to be about 4.6 billion years old). At this very early stage in geological history, there was little or no oxygen in the atmosphere. So the very oldest banded iron formations cannot be the result of O2-dependent oxidation.
In 1993, bacteria were discovered which do not need oxygen but can oxidize Fe(II) by using energy from light (anoxygenic phototrophic iron-oxidizing bacteria). Studies by Professor Kappler’s team in 2005 and 2010 showed that these bacteria transform dissolved ferric iron into iron oxide (rust) — like the material in the early iron ores. Now, the geomicrobiologists from Tübingen have been able to demonstrate that, by examining the identity and structural properties of the iron minerals, it is possible to tell that the minerals were deposited by iron-oxidizing microbes and not by oxygen made available by the action of cyanobacteria. To do this, the researchers placed different amounts of organic material together with iron minerals into gold capsules and increased the pressure and temperature to simulate the transformation of the minerals over geological time. They ended up with structures of iron carbonate minerals (siderite, FeCO3), just as they occur in geological iron formations. In particular, they were able to distinguish iron carbonate structures which had been formed in the presence of a rather small amount of organic compounds (microbial biomass) from those formed in the presence of a larger amount.
This research not only provides the first clear evidence that microorganisms were directly involved in the deposition of Earth’s oldest iron formations; it also indicates that large populations of oxygen-producing cyanobacteria were at work in the shallow areas of the ancient oceans, while deeper water still reached by the light (the photic zone) tended to be populated by anoxyenic or micro-aerophilic iron-oxidizing bacteria which formed the iron deposits.
Note : The above story is reprinted from materials provided by Universitaet Tübingen.
White Desert (known as Sahara el Beyda, with the word sahara meaning a desert). The White Desert of Egypt is located 45 km (28 mi) north of the town of Farafra. The desert has a white, cream color and has massive chalk rock formations that have been created as a result of occasional sandstorm in the area.
The majority of the valley is devoid of vegetation desert today. Rock and subsoil are usually made of limestone or chalk.
The valley is flat and is interrupted only by a few isolated standing conical hills – both north and south of the city of el-Farafra, they are called el-Qunna, mostly spoken el-Gunna (Arabic: القنة, al-Qunna, “the pinnacle “). East of el-Quss-Abu-Sa ? id plateaus are also numerous small limestone mountains witnesses.
The soil is blown with sand. It can be here but in places some minerals such as pyrite and marcasite (iron disulfide are both, but with different crystal form), especially in the north of the valley in the area of ? Ain Bischw?. The materials have been but never mined in mines.
The result is the desert from the remains of microscopic sea creatures whose habitat was located here before about 80 million years ago. After the disappearance of the sea winds ensured for the expression of today’s rock whose shape was determined by the composition and hardness of the rocks and their layer sequence. Occasionally can find fossils such as clams or sea urchins.
Video :
Photos :
Note : The above story is reprinted from materials provided by Wikipedia 1 &2
Copyright of The Video & Photos Owen To Geology Page
Book Name : Rocks and Minerals By : MONICA PRICE
KEVIN WALSH DK LONDON Senior Art Editor: Ina Stradins Senior Editor: Angeles Gavira Editors: Georgina Garner, Bella Pringle DTP Designer: John Goldsmid Production Controller: Melanie Dowland Managing Art Editor: Phil Ormerod Publishing Manager: Liz Wheeler Art Director :Bryn Walls Publishing Director: Jonathan Metcalf DK DELHI Designers: Romi Chakraborty,
Malavika Talukdar DTP Designers: Balwant Singh,
Sunil Sharma, Pankaj Sharma Editors : Glenda Fernandes, Rohan Sinha Managing Art Editor: Aparna Sharma
A study by University of Utah mining engineers and seismologists found 2,189 suspected seismic events before and after Utah’s deadly Crandall Canyon coal mine collapse in 2007, and 1,328 of those events have a high probability of being real: 759 seismic events before the collapse (many related to mining) and 569 aftershocks (some related to rescue efforts). The high-probability events shown here reveal seismic activity clustered in three areas, two of which already were known: near the east end of the mine (right) and where miners were working, toward the west end of the mine (left of center). But the third cluster, at the mine’s west end (far left) was revealed by the new study. It shows the collapse was at least as big and possibly larger than a 2008 University of Utah study that revealed the collapse extended from the east part of the mine to the area where miners were working. (Credit: Tex Kubacki, University of Utah)
A new University of Utah study has identified hundreds of previously unrecognized small aftershocks that happened after Utah’s deadly Crandall Canyon mine collapse in 2007, and they suggest the collapse was as big — and perhaps bigger — than shown in another study by the university in 2008.
Mapping out the locations of the aftershocks “helps us better delineate the extent of the collapse at Crandall canyon. It’s gotten bigger,” says Tex Kubacki, a University of Utah master’s student in mining engineering.
“We can see now that, prior to the collapse, the seismicity was occurring where the mining was taking place, and that after the collapse, the seismicity migrated to both ends of the collapse zone,” including the mine’s west end, he adds.
Kubacki was scheduled to present the findings Friday in Salt Lake City during the Seismological Society of America’s 2013 annual meeting.
Six coal miners died in the Aug. 6, 2007 mine collapse, and three rescuers died 10 days later. The mine’s owner initially blamed the collapse on an earthquake, but the University of Utah Seismograph Stations said it was the collapse itself, not an earthquake, that registered on seismometers.
A 2008 study by University of Utah seismologist Jim Pechmann found the epicenter of the collapse was near where the miners were working, and aftershocks showed the collapse area covered 50 acres, four times larger than originally thought, extending from crosscut 120 on the east to crosscut 143 on the west, where miners worked. A crosscut is a north-south tunnel intersecting the mine’s main east-west tunnels.
In the new study, the collapse area “looks like it goes farther west — to the full extent of the western end of the mine, Kubacki says.
Study co-author Michael “Kim” McCarter, a University of Utah professor of mining engineering, says the findings are tentative, but “might extend the collapse farther west.” He is puzzled because “some of that is in an area where no mining had occurred.”
Kubacki says one theory is that the seismic events at the west end and some of those at the eastern end of the mine may be caused by “faulting forming along a cone of collapse” centered over the mine.
Kubacki and McCarter conducted the new study with seismologists Keith Koper and Kris Pankow of the University of Utah Seismograph Stations. McCarter and Pankow also coauthored the 2008 study.
Before the new study, researchers knew of about 55 seismic events — down to magnitude 1.6 — near the mine before and after the collapse, which measured 3.9 on the local magnitude scale and 4.1 on the “moment” magnitude scale that better reflects energy release, Kubacki says.
The new study analyzed records of seismometers closest to the mine for evidence of tremors down to magnitudes minus-1, which Kubacki says is about one-tenth the energy released by a hand grenade. He found:
– Strong statistical evidence there were at least 759 seismic events before the mine collapse and 569 aftershocks.
– Weak evidence there were as many as 1,022 seismic events before the collapse and 1,167 aftershocks.
“We’ve discovered up to about 2,000 previously unknown events spanning from July 26 to Aug. 30, 2007,” Kubacki says, although some of the weak-evidence events may turn out not to be real or to be unrelated to the collapse.
The seismic events found in the new study show tremors clustered in three areas: the east end of the collapse area, the area where miners were working toward the mine’s west end, and — new in this study — at the mine’s west end, beyond where miners worked.
“We have three clusters to look at and try to come up with an explanation of why there were three,” McCarter says. “They are all related to the collapse.”
Some of the tremors in the eastern cluster are related to rescue attempts and a second collapse that killed three rescuers, but some remain unexplained, he adds.
Kubacki says most of the seismic activity before the collapse was due to mining, although scientists want to investigate whether any of those small jolts might have been signs of the impending collapse. So far, however, “there is nothing measured that would have said, ‘Here’s an event [mine collapse] that’s ready to happen,” McCarter says.
Kubacki came up with the new numbers of seismic events by analyzing the records of seismometers closest to Crandall Canyon (about 12 miles away). “We took the known seismic events already in the catalog and searched for events that looked the same,” he adds. “These new events kept popping up. There are tiny events that may show up on one station but not network-wide.”
“Any understanding we can get toward learning how and why mine collapses happen is going to be of interest to the mining community,” Kubacki says.
McCarter adds: “We are looking at the Crandall Canyon event because we have accurate logs and very extensive seismic data, and that provides a way of investigating the data to see if anything could be applied to other mines to improve safety.”
Note : The above story is reprinted from materials provided by University of Utah.
Outline of Dahalokely tokana with a human for scale, showing known bones in white and missing areas patterned after related animals. (Credit: Copyright Andrew Farke and Joseph Sertich)
The first new species of dinosaur from Madagascar in nearly a decade was announced today, filling an important gap in the island’s fossil record.
Dahalokely tokana (pronounced “dah-HAH-loo-KAY-lee too-KAH-nah”) is estimated to have been between nine and 14 feet long, and it lived around 90 million years ago. Dahalokely belongs to a group called abelisauroids, carnivorous dinosaurs common to the southern continents. Up to this point, no dinosaur remains from between 165 and 70 million years ago could be identified to the species level in Madagascar-a 95 million year gap in the fossil record. Dahalokely shortens this gap by 20 million years.
The fossils of Dahalokely were excavated in 2007 and 2010, near the city of Antsiranana (Diego-Suarez) in northernmost Madagascar. Bones recovered included vertebrae and ribs. Because this area of the skeleton is so distinct in some dinosaurs, the research team was able to definitively identify the specimen as a new species. Several unique features — including the shape of some cavities on the side of the vertebrae — were unlike those in any other dinosaur. Other features in the vertebrae identified Dahalokely as an abelisauroid dinosaur.
When Dahalokely was alive, Madagascar was connected to India, and the two landmasses were isolated in the middle of the Indian Ocean. Geological evidence indicates that India and Madagascar separated around 88 million years ago, just after Dahalokely lived. Thus, Dahalokely potentially could have been ancestral to animals that lived later in both Madagascar and India. However, not quite enough of Dahalokely is yet known to resolve this issue. The bones known so far preserve an intriguing mix of features found in dinosaurs from both Madagascar and India.
“We had always suspected that abelisauroids were in Madagascar 90 million years ago, because they were also found in younger rocks on the island. Dahalokely nicely confirms this hypothesis,” said project leader Andrew Farke, Augustyn Family Curator of Paleontology at the Raymond M. Alf Museum of Paleontology. Farke continued, “But, the fossils of Dahalokely are tantalizingly incomplete — there is so much more we want to know. Was Dahalokely closely related to later abelisauroids on Madagascar, or did it die out without descendents?”
The name “Dahalokely tokana” is from the Malagasy language, meaning “lonely small bandit.” This refers to the presumed carnivorous diet of the animal, as well as to the fact that it lived at a time when the landmasses of India and Madagascar together were isolated from the rest of the world.
“This dinosaur was closely related to other famous dinosaurs from the southern continents, like the horned Carnotaurus from Argentina and Majungasaurus, also from Madagascar,” said project member Joe Sertich, Curator of Dinosaurs at the Denver Museum of Nature & Science and the team member who discovered the new dinosaur. “This just reinforces the importance of exploring new areas around the world where undiscovered dinosaur species are still waiting,” added Sertich.
The research was funded by the Jurassic Foundation, Sigma Xi, National Science Foundation, and the Raymond M. Alf Museum of Paleontology. The paper naming Dahalokely appears in the April 18, 2013, release of the journal PLOS ONE.
Note : The above story is reprinted from materials provided by Raymond M. Alf Museum of Paleontology.
Earth’s Core provides a wealth of information for those people interested in Rocks, Gems and Minerals. it contains detailed information on hundreds of gems and minerals as well as a detail glossary of terms.
Earth’s Core is designed to be used on desktops set to 1024×768 or better, it requires 70MB of disk space.
Features
Detailed descriptions and images on 600 minerals
Detailed descriptions and images on 300 gems
Detailed descriptions and images on 200 rocks
900 glossary items
2100 pictures
Fully searchable content
PLUS, it also contains most of the features of my Periodic Table software;
Detailed information on each element, its allotropes, compounds, reactions and images.
Biographies for the important scientists and element discoverers
Screenshots
Information and pictures of the elements of the Periodic Table
