Geological Institute

Sofia, Bulgaria

Geological Institute

Sofia, Bulgaria
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News Article | May 25, 2017

A new species of a fossil pliosaur (large predatory marine reptile from the 'age of dinosaur') has been found in Russia and profoundly change how we understand the evolution of the group, says an international team of scientists. Spanning more than 135 Ma during the 'Age of Dinosaurs', plesiosaur marine reptiles represent one of longest-lived radiations of aquatic tetrapods and certainly the most diverse one. Plesiosaurs possess an unusual body shape not seen in other marine vertebrates with four large flippers, a stiff trunk, and a highly varying neck length. Pliosaurs are a special kind of plesiosaur that are characterized by a large, 2m long skull, enormous teeth and extremely powerful jaws, making them the top predators of oceans during the 'Age of Dinosaurs'. In a new study to be published today in the journal Current Biology, the team reports a new, exceptionally well-preserved and highly unusual pliosaur from the Cretaceous of Russia (about 130 million years ago). It has been found in Autumn 2002 on right bank of the Volga River, close to the city of Ulyanovsk, by Gleb N. Uspensky (Ulyanovsk State University), one of the co-authors of the paper. The skull of the new species, dubbed "Luskhan itilensis", meaning the Master Spirit from the Volga river, is 1.5m in length, indicating a large animal. But its rostrum is extremely slender, resembling that of fish-eating aquatic animals such as gharials or some species of river dolphins. "This is the most striking feature, as it suggests that pliosaurs colonized a much wider range of ecological niches than previously assumed" said Valentin Fischer, lecturer at the Université de Liège (Belgium) and lead author of the study. By analysing two new and comprehensive datasets that describe the anatomy and ecomorphology of plesiosaurs with cutting edge techniques, the team revealed that several evolutionary convergences (a biological phenomenon where distantly related species evolve and resemble one another because they occupy similar roles, for example similar feeding strategies and prey types in an ecosystem) took place during the evolution of plesiosaurs, notably after an important extinction event at the end of the Jurassic (145 million years ago). The new findings have also ramifications in the final extinction of pliosaurs, which took place several tens of million years before that of all dinosaurs (except some bird lineages). Indeed, the new results suggest that pliosaurs were able to bounce back after the latest Jurassic extinction, but then faced another extinction that would - this time - wipe them off the depths of ancient oceans, forever. Fischer Valentin, Benson Roger B J, Zverkov Nikolai G, Soul Laura C, Arkhangelsky Maxim S, Lambert Olivier, Stenshin Ilya M, Uspensky Gleb N & Druckenmiller Patrick S. 2017. Plasticity and convergence in the evolution of short-necked plesiosaurs. Current Biology 27 DOI:10.1016/j.cub.2017.04.052. The research was a collaboration between the Université de Liège (Belgium), the University of Oxford (UK), the Lemonosov State University (Russia), the Geological Institute of the Russian Academy of Sciences (Russia), the Smithsonian Institution (USA), the Saratov State Technical and Saratov State universities (Russia), the Royal Belgian Institute of Natural Sciences (Belgium), the I.A. Goncharov Ulyanovsk Regional Natural History Museum (Russia), the Ulyanovsk State University (Russia) and the University of Alaska Fairbanks (USA).

Steiner B.,Spectraseis | Steiner B.,Geological Institute | Saenger E.H.,Spectraseis | Saenger E.H.,Geological Institute | Schmalholz S.M.,Institute Of Geologie Et Of Paleontologie
Geophysics | Year: 2011

Time-reverse imaging is a wave propagation algorithm for locating sources. Signals recorded by synchronized receivers are reversed in time and propagated back to the source location by elastic wavefield extrapolation. Elastic wavefield extrapolation requires a P-wave as well as an S-wave velocity model. The velocity models available from standard reflection seismic methods are usually restricted to only P-waves. In this study, we use synthetically produced time signals to investigate the accuracy of seismic source localization by means of time-reverse imaging with the correct P-wave and a perturbed S-wave velocity model. The studies reveal that perturbed S-wave velocity models strongly influence the intensity and position of the focus. Imaging the results with the individual maximum energy density for both body wave types instead of mixed modes allows individual analysis of the two body waves. P-wave energy density images render stable focuses in case of a correct P-wave and incorrect S-wave velocity model. Thus, P-wave energy density seems to be a more suitable imaging condition in case of a high degree of uncertainty in the S-wave velocity model. © 2011 Society of Exploration Geophysicists.

Galy V.,Woods Hole Oceanographic Institution | Peucker-Ehrenbrink B.,Woods Hole Oceanographic Institution | Eglinton T.,Woods Hole Oceanographic Institution | Eglinton T.,Geological Institute
Nature | Year: 2015

Riverine export of particulate organic carbon (POC) to the ocean affects the atmospheric carbon inventory over a broad range of timescales. On geological timescales, the balance between sequestration of POC from the terrestrial biosphere and oxidation of rock-derived (petrogenic) organic carbon sets the magnitude of the atmospheric carbon and oxygen reservoirs. Over shorter timescales, variations in the rate of exchange between carbon reservoirs, such as soils and marine sediments, also modulate atmospheric carbon dioxide levels. The respective fluxes of biospheric and petrogenic organic carbon are poorly constrained, however, and mechanisms controlling POC export have remained elusive, limiting our ability to predict POC fluxes quantitatively as a result of climatic or tectonic changes. Here we estimate biospheric and petrogenic POC fluxes for a suite of river systems representative of the natural variability in catchment properties. We show that export yields of both biospheric and petrogenic POC are positively related to the yield of suspended sediment, revealing that POC export is mostly controlled by physical erosion. Using a global compilation of gauged suspended sediment flux, we derive separate estimates of global biospheric and petrogenic POC fluxes of 157-50+74 and 43-25+61 megatonnes of carbon per year, respectively. We find that biospheric POC export is primarily controlled by the capacity of rivers to mobilize and transport POC, and is largely insensitive to the magnitude of terrestrial primary production. Globally, physical erosion rates affect the rate of biospheric POC burial in marine sediments more strongly than carbon sequestration through silicate weathering. We conclude that burial of biospheric POC in marine sediments becomes the dominant long-term atmospheric carbon dioxide sink under enhanced physical erosion. © 2015, Macmillan Publishers Limited. All rights reserved.

Herman F.,Geological Institute | Rhodes E.J.,University of California | Braun J.,Joseph Fourier University | Heiniger L.,Geological Institute
Earth and Planetary Science Letters | Year: 2010

Glaciers and rivers control the shape of the high relief topography of mountain ranges. However, their relative contribution in response to climatic oscillations and tectonic forcing and whether landscapes can reach equilibrium conditions during the Quaternary are still unclear. Here we introduce a new thermochronometer of exceptionally low closure temperature (ca. 30-35°C) based on Optically Stimulated Luminescence (OSL) dating and illustrate how it may be used to measure relief evolution and exhumation rates within the last glacial cycle in the Southern Alps of New Zealand, one of the most tectonically active orogens and an area that has experienced rapid, high magnitude climate changes. We find that exhumation rates have remained steady over the last glacial cycle and match rates observed at a million year timescale. This suggests that, despite an extreme exhumation rate of the order of 800. m in 100. ka, and the fact that in the last ca. 11-18. ka most hillslope sides have changed from U to V-shape valleys and have been dissected by debris-flows, landslides and rock avalanches, the mean exhumation rates have remained nearly constant. This may imply that tectonics, not climate, has a primary control on the rates of exhumation in tectonically active and wet mountain belts. On the contrary, tectonically active mountain ranges might not attain equilibrium on similar timescales in weathering and/or transport limited landscapes as, for example, in arid regions. © 2010 Elsevier B.V.

Bonev N.,Sofia University | Spikings R.,University of Geneva | Moritz R.,University of Geneva | Marchev P.,Geological Institute | Collings D.,University of Leeds
Lithos | Year: 2013

We quantify the timing of the Tertiary crustal extension in the eastern Rhodope Massif of south Bulgaria using 40A{cyrillic}r/39A{cyrillic}r geochronology to constrain the temporal evolution of exhumation of the metamorphic domes. 40A{cyrillic}r/39A{cyrillic}r analyses of mineral phases with different closure temperatures extracted from metamorphic rocks collected in the footwall and the hanging wall of the extensional system reveal the low-temperature cooling history towards shallow crustal levels. The results reveal that subsequent to regional amphibolite facies metamorphism (i) the hanging wall gradually cooled between 500 and 300°C during the Paleocene to Late Eocene (64-34Ma), starting at a low rate of 25°C/Ma and increasing to 50-67°C/Ma during 38-34Ma, (ii) cooling below 400-300°C of the footwall beneath the extensional detachments occurred in the Middle-Late Eocene (39-35.5Ma) at an average rate of 35°C/Ma. 40A{cyrillic}r/39A{cyrillic}r data from the metamorphic basement has been combined with 40A{cyrillic}r/39A{cyrillic}r data from the volcanic and hydrothermal rocks in the vicinity to the extensional domes, to determine the temporal relationships between extensional tectonics, ore-forming and magmatic processes in the region. Extension of the high-grade basement, the ore-formation and volcanism overlaps within a 5Ma lasting time interval, especially during the cooling and exhumation of the footwall. The eastern Rhodope Massif records an early stage of Eocene extension within the Aegean extensional province, where distinct crustal-scale processes occurred simultaneously implying the presence of cause and effect processes, and thus represents a key example of coeval continental extension, magmatism and hydrothermal activity in the late-stage evolution of the orogens. © 2013 Elsevier B.V.

Bonev N.,Sofia University | Spikings R.,University of Geneva | Moritz R.,University of Geneva | Marchev P.,Geological Institute
Tectonophysics | Year: 2010

In the northeastern Rhodope Massif, the Kulidzhik nappe exposes a unique juxtaposition of a high-grade basement allochthon onto a low-grade Mesozoic unit, and the counterpart Pelevun extensional allochthon belonging to the same unit. The Kulidzhik nappe tectonostratigraphy comprises structurally upward: (i) a lower unit consisting of high-grade basement orthogneisses; (ii) a low-grade greenschist-phyllite unit consisting of Jurassic extrusive rocks and metasedimentary rocks; (iii) the nappe allochthon built by the lower high-grade basement unit orthogneisses; and (iv) Eocene sedimentary rocks and Oligocene volcanic cover rocks. The Pelevun extensional allochthon is heterogeneous, and consists of Mesozoic low-grade unit marbles and greenschists and the upper high-grade basement unit. We have combined structure and kinematics, with lithological information and 40Ar/39Ar geochronology to constrain the tectonic evolution and regional significance of the Kulidzhik nappe and the Pelevun extensional allochthon. Mineral chemistry reveals igneous phases of the granitic protolith of the allochthonous orthogneisses with textures related to ductile deformation and metamorphism higher than 500°C. Their trace element patterns are indistinguishable from the high-grade basement orthogneisses in the eastern Rhodope. Mineral chemistry of the metamorphic assemblage in the underlying greenschists is consistent with medium-grade greenschist-facies metamorphism at temperatures well below 450°C, whose geochemistry defines transitional MORB to IAT affinities with a strong arc imprint. The greenschist's composition is extremely similar to the composition of a supra-subduction zone Jurassic arc extrusive suite that occurs in the low-grade unit of the eastern Rhodope. The structural elements in all of the tectono-metamorphic units and the nappe surface indicate top-to-the NNE tectonic transport. Deformation evolved from ductile to brittle conditions coevally with a progressive decrease from lower amphibolite to weak greenschist-facies metamorphism towards the structural top. Two klippen gave plateau 40Ar/39Ar mica ages of 154.23±0.66Ma and 156.70±0.81Ma, respectively, which reflect cooling following the greenschist-facies event below ~350°C, during shallow crustal level thrust emplacement and exhumation of the Kulidzhik allochthon. The hanging-wall Pelevun extensional allochthon preserves an internal NNE-directed ductile tectonic transport trend, but is underlain by a SSW-directed ductile-brittle extensional detachment and has experienced NE-SW brittle extension on high-angle normal faults. An amphibole 40Ar/39Ar inverse isochron age of 156.58±0.60Ma constrains a Late Jurassic upper greenschist-facies tectono-metamorphic event, whereas a white mica plateau age of 39.66±0.47Ma provides evidence for Middle Eocene cooling and exhumation of the Pelevun extensional allochthon in the hanging wall of the detachment. We relate the Kulidzhik nappe to Late Jurassic crustal deformation during arc-continental margin collision that involved NNE-directed nappe staking and metamorphism of continental margin basement and island arc units. The nappe shares a tectono-metamorphic history with the nappes of the adjacent Strandzha Massif, implying a region-wide early Alpine orogenic system. Our results reveal a record of early Alpine thrust tectonics and show the significance of crustal accretion-related assembly for the tectonic evolution of the Rhodope Massif. Both the Late Jurassic thrusting event and the subsequent Cretaceous thrusting event thickened the Rhodope crust creating crustal instability, which influenced Tertiary crustal extension. © 2010 Elsevier B.V.

Rolland Y.,University of Nice Sophia Antipolis | Sosson M.,University of Nice Sophia Antipolis | Adamia S.,Institute of Geophysics | Sadradze N.,Geological Institute
Gondwana Research | Year: 2011

Variscan to Alpine magmatic activity on the North Tethys active Eurasian margin in the Caucasus region is revealed by 40Ar/39Ar ages from rocks sampled in the Georgian Crystalline basement and exotic blocs in the Armenian foreland basin. These ages provide insights into the long duration of magmatic activity and related metamorphic history of the margin, with: (1) a phase of transpression with little crustal thickening during the Variscan cycle, evidenced by HT-LP metamorphism at 329-337Ma; (2) a phase of intense bimodal magmatism at the end of the Variscan cycle, between 303 and 269Ma, which is interpreted as an ongoing active margin during this period; (3) further evolution of the active margin evidenced by migmatites formed at ca. 183Ma in a transpressive setting; (4) paroxysmal arc plutonic activity during the Jurassic (although the active magmatic arc was located farther south than the studied crystalline basements) with metamorphic rocks of the Eurasian basement sampled in the Armenian foreland basin dated at 166Ma; (5) rapid cooling suggested by similar within-error ages of amphibole and muscovite sampled from the same exotic block in the Armenian fore-arc basin, ascribed to rapid exhumation related to extensional tectonics in the arc; and finally (6) cessation of 'Andean'-type magmatic arc history in the Upper Cretaceous. Remnants of magmatic activity in the Early Cretaceous are found in the Georgian crystalline basement at c. 114Ma, which is ascribed to flat slab subduction of relatively hot oceanic crust. This event corresponds to the emplacement of an oceanic seamount above the N Armenian ophiolite at 117Ma. The activity of a hot spot between the active Eurasian margin and the South Armenian Block is thought to have heated and thickened the Neo-Tethys oceanic crust. Finally, the South Eurasian margin was uplifted and transported over this hot oceanic crust, resulting in the cessation of subduction and the erosion of the southern edge of the margin in Upper Cretaceous times. Emplacement of Eocene volcanics stitches all main collisional structures. © 2011 International Association for Gondwana Research.

News Article | March 17, 2016

Experts examined a Pleistocene puppy that had been frozen for 12,400 years, and a scientific team wants to clone it back to life. Among the experts present at the observation is South Korean scientist Hwang Woo-suk, who is best known for his interest in cloning woolly mammoths. Now, he plans to include the ancient canid in his "resurrection" project. In 2011, experts were able to unearth what is believed to be the sibling of the frozen Pleistocene puppy. However, the latter is better preserved hence, scientists are hoping to get more valuable data, says researcher Sergey Fedorov from North-East Federal University. Woo-suk also seemed pleased with the way the puppy was preserved. In fact, he was excited. The team looked at the carcass comprehensively, touched the soft tissues and looked at the best-preserved body parts. Woo-suk then took samples of the ear cartilage, muscles and skin. Another remarkable finding is that the brain of the puppy is also preserved well. Dr. Pavel Nikolsky from the Geological Institute in Moscow even made fairly high estimates. "The degree of preservation is about 70 to 80 percent," he says. As of now, the parts are yet to be extracted. What are available now are results of magnetic resonance imaging scans. Although the brain has dried out, obviously, vital parts like the cerebellum, pituitary gland and both parencephalon are still observable. Nikolsky said it can be confirmed that this is the first time that they have collected a brain of a Pleistocene dog — the first predator's brain from the said period. The team also obtained samples from the ground surrounding the carcass, hoping to discover bacteria present. In the future, they will compare the specimen to the intestines of the puppy and see if it also thrives inside the animal. They also took samples to determine parasites such as fleas and ticks that are characteristics of this type of puppy. The puppy was unearthed in an icy grave near the village of Tumat in the Ust-Yansky district of the Sakha Republic, Russia. The location was close to signs of possible early human activities. When the experts found the puppy, Fedorov says they knew they got a perfect find with the well-reserved nose, tail and even hair. Experts believe that the puppy died in a landslide. The animals were then sealed in the permafrost and subsequently mummified. Initial DNA tests revealed that the animal was a dog and not a wolf, as previously thought. However, scientists will perform more work to establish the truth as the genetic makeup of the two animals are highly similar.

Yaneva M.,Geological Institute | Shanov S.B.,Bulgarian Geophysical Society
8th Congress of the Balkan Geophysical Society, BGS 2015 | Year: 2015

The sedimenthological model of Lom Lignite Basin (North Bulgaria) is represented by a set of maps, elaborated for the principal geological layers (sedimentary complexes) on the base of integrated analysis of data from boreholes, seismic profiling, seismic well logging, and vertical electrical sounding.

News Article | March 11, 2016

Tanzania’s Olduvai Gorge is considered one of the most important paleoanthropological sites.  Toiling in the dirt for decades, paleoanthropologists Mary and Louis Leakey found many mammalian fossils and stone tools at the site. In 1959, however, Mary Leakey found hominin skull fragments and teeth. The find proved that hominins were present in early East Africa. Now, in the early 21st century, scientists have reconstructed what life might have been like for the human ancestors occupying the site some 1.8 million years ago. The team published their work in the journal Proceedings of the National Academy of Sciences. ”It was tough living,” said study co-author Gail M. Ashley, of Rutgers Univ.’s Dept. of Earth and Planetary Sciences, in a statement. “It was a very stressful life because they were in continual competition with carnivores for their food.” Ashley has performed research at the Olduvai Gorge site since 1994. Her co-authors include colleagues from the Geological Institute in Zurich, Univ. of Madrid, and Pennsylvania State Univ. By analyzing the soils in one geological bed, the researchers were able to reconstruct the ancient plants and landscape that surrounded the fossilized hominin remains. The two species found at the site included Paranthropus boisei and Homo habilis. While both species measured between 4.5 and 5.5 feet tall, Paranthropus boisei was robust and small-brained and Homo habilis was lighter-boned with a bigger brain, according to Rutgers Univ. Each species had a lifespan between 30 and 40 years. Based on the analysis, the researchers found the site was shaded by palm and acacia trees, had a freshwater spring, and wetlands and grasslands. “We don’t think they were living there,” Ashley said. “We think they were taking advantage of the freshwater source that was nearby.” Additionally, the site had a substantial amount of fossils from giraffes, elephants, and wildebeests, among other mammals. Whether the hominins killed or scavenged for meat, the researchers believe they feasted under forest cover to ensure their safety from predators. The researchers believe meat consumption played an important role in the evolution of hominins. According to Ashley, increase in human brain size is linked to increased protein.

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