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Foster W.J.,University of Plymouth | Foster W.J.,Natural History Museum in London | Danise S.,University of Plymouth | Danise S.,University of Georgia | And 4 more authors.
Palaeogeography, Palaeoclimatology, Palaeoecology | Year: 2015

Climate warming during the late Permian is associated with the most severe mass extinction event of the Phanerozoic, and the expansion of hypoxic and anoxic conditions in shallow shelf settings. It has been hypothesised that wave aeration provided a 'habitable zone' in the shallowest environments that allowed the survival and rapid recovery of benthic invertebrates during the Early Triassic. We test this hypothesis by studying the rock and fossil records of the Aggtelek Karst, Hungary. Nearshore settings recorded in the Bódvaszilas Sandstone Formation and units A and D of the Szin Marl Formation are characterised by taxonomically homogenous fossil assemblages of low diversity and low evenness. Ecological and taxonomic recovery in this environmental setting was hampered by persistent environmental stress. This stress is attributed to increased runoff related to climate warming during the Early Triassic that resulted in large salinity fluctuations, increased sedimentation rates and eutrophication that led to seasonal hypoxia and an environment only favourable for opportunistic taxa. In contrast, shoal and mid-ramp settings further offshore are characterised by high diversity faunas with a greater functional complexity. Prior to the late Spathian Tirolites carniolicus Zone, the shelly fossils and trace fossils are limited to settings aerated by wave activity, which supports the habitable zone hypothesis. In the Tirolites carniolicus Zone, however, the oxygen minimum zone retreats offshore and the habitable deeper shelf settings are rapidly colonised by shallow water taxa, evidenced by the highest levels of diversity and bioturbation recorded in the study. Locally, full recovery of marine ecosystems is not recorded until the Illyrian, with the establishment of a sponge reef complex. © 2015.

Szanyi G.,MTA CSFK GGI | Suranyi G.,Geophysical and Space Science Research Group | Leel-ossy S.,Eotvos Lorand University
Quaternary Geochronology | Year: 2012

Several thermal karstic caves are known in the Rózsadomb area of Budapest, Hungary. On a small, 5-6 km2 territory more than 50 km of cave passages were mapped and documented to host significant cave raft deposits. Cave rafts precipitate at the surface of karst water lakes, and are potential indicators of former karst water levels.Thirty-two samples of cave rafts collected from different elevations in Pál-völgy Cave and five from Szemlo{doubleacute}-hegy Cave were dated by U-series methods using single-collector ICP-MS. Nine samples were older than 450 ka, the upper limit of U-series age determination. Uplift of the area and the associated history of karst paleo-water levels was assessed using the age and present-day elevation above sea level of the cave rafts.A two-phase uplift history was revealed. A slow emergence of the area was succeeded by more rapid uplift. Its beginning varies from cave to cave, suggesting differential movements of 0.15-0.32 mm/y. © 2012 Elsevier B.V.

Kiss G.,Eotvos Lorand University | Molnar F.,Eotvos Lorand University | Palinkas L.A.,University of Zagreb | Kovacs S.,Geophysical and Space Science Research Group | Horvatovic H.,Geological Survey of Bosnia and Herzegovina
International Journal of Earth Sciences | Year: 2012

Comparative volcanological, mineralogical, petrological, and geochemical studies of blocks of Triassic submarine basalt occurrences hosted by the Jurassic mélange have been carried out. The studied localities are located in displaced parts of the Dinarides in NE-Hungary (Darnó Unit), in the Dinarides (Kalnik Mts., Croatia and Vareš-Smreka, Bosnia and Herzegovina), and in the Hellenides (Stragopetra, Greece). The common characteristic of the studied occurrences is the well observable result of the lava-water-saturated sediment mingling, i. e., the presence of the so-called carbonate peperitic facies. Mixing of the basaltic lava with pelagic lime mud (representing the unconsolidated stage of the red, micritic limestone), as well as fluid inclusion and chlorite thermometry data support that the carbonate peperite was formed above CCD and at the Bosnian locality, a shallower water, about 1.4 km depth is proven. The igneous rocks show mainly within-plate basalt geochemical characteristics; MORB signatures are not common. Low temperature (<200°C) hydrothermal alteration is characteristic to the pillow basalt blocks with peperitic facies. The similarities in the volcanological, geochemical, and textural characteristics observed at the different localities support a strong genetic connection among them. The results of this study suggest to the advanced rifting stage origin of the Triassic basaltic suits and their distinction from the true oceanic basalt pillow units of the Dinarides can be based on the occurrences of the peperite facies. © 2011 Springer-Verlag.

Economically important black shale-hosted manganese carbonate deposits occur in certain parts of the Transdanubian Range in Hungary. These ore deposits were formed in a short interval coinciding with the Early Toarcian global anoxic and mass extinction event that was associated with drastic perturbations of the oceanographic conditions. During the Early Jurassic the Transdanubian Range Unit was located between two ocean basins. Simultaneous opening of these two basins created an extensional regime resulting in a complex topography with tectonically-controlled small scale basins above an attenuated continental lithosphere. Sluggish circulation led to the development of layered water masses in certain parts of these basins, with oxygenated upper and oxygen-depleted lower reservoirs. This paleogeographic and paleoenvironmental setting favoured the microbially-mediated accumulation of manganese and iron. © 2011 Elsevier B.V..

Leel-Ossy S.,Eotvos Lorand University | Szanyi G.,HAS Geodetic and Geophysical Research Institute | Suranyi G.,Geophysical and Space Science Research Group
International Journal of Speleology | Year: 2011

With the discovery of the József-hegy Cave, a cave of hydrothermal origin with an abundance of minerals unknown so far in Hungary came to light. Diversity and the frequency of the occurrence of crystals make this cave similar to the Lechuguilla Cave, even if the dimensions of the mineral precipitations and the passages do not compare in scale. The variety and mass of carbonates and sulphates are surprising. This paper describes the minerals and speleothems of the József-hegy Cave, their occurrence and genesis, including determined ages. The 41 U/Th measurements suggest that speleothems begun to develop in the upper level of the cave more than 350 ka ago. Some of these dated old speleothems were developing in dry passages, thus the uppermost passages of the József-hegy Cave have been dry at least for 350 ka. The karst water level was still at the main passage 200 ka ago and dropped to 120 m asl by the time of ~100 ka before present.

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