Search results for " depositional environment"
showing 10 items of 129 documents
Depositional model in subglacial cavities, Killiney Bay, Ireland. Interactions between sedimentation, deformation and glacial dynamics
2012
Subglacial meltwater drainage and sedimentary processes play a major role in ice-sheet dynamic but there is a lack of study of subglacial environment because modern ice-sheet beds remain inaccessible. Previous authors already intended to provide diagnostic criterion and recent investigations suggest that fluid pressure variations are a key factor in subglacial environment. This paper investigated the late Devensian sedimentary record in order to describe subglacial sedimentological facies associations and deformation features related to fluid overpressures. We used an integrated approach, based on stratigraphy, sedimentology and deformations styles to demonstrate a subglacial depositional m…
Materiales del Paleolítico Superior en Cova Negra (Xàtiva) y su interés para establecer los procesos de su secuencia estratigráfica
2017
En este trabajo se analizan los materiales líticos adscritos al Paleolítico Superior obtenidos en Cova Negra a lo largo de las campañas de excavación de los años 30, 50 y 80 del pasado siglo y en las campañas de 2013-2016. La atención se centra en el estudio de los soportes, los núcleos y el material retocado, y se efectúa una primera aproximación con respecto a la cronología y periodos a los que remiten las piezas retocadas. El principal interés de estos materiales reside en confirmar que la ocupación de la cavidad no se limitó al Paleolítico Medio, ni a momentos iniciales de la secuencia del Paleolítico Superior, lo que facilita una evaluación del alcance de los procesos de alteración pos…
Observations of atmospheric chemical deposition to high Arctic snow
2017
Abstract. Rapidly rising temperatures and loss of snow and ice cover have demonstrated the unique vulnerability of the high Arctic to climate change. There are major uncertainties in modelling the chemical depositional and scavenging processes of Arctic snow. To that end, fresh snow samples collected on average every 4 days at Alert, Nunavut, from September 2014 to June 2015 were analyzed for black carbon, major ions, and metals, and their concentrations and fluxes were reported. Comparison with simultaneous measurements of atmospheric aerosol mass loadings yields effective deposition velocities that encompass all processes by which the atmospheric species are transferred to the snow. It is…
Textural features and isotope geochemistry of the Scillato travertine (north-central Sicily): genetic implications.
2015
The travertine deposit, outcropping near the Scillato town (north-central Sicily), was originated by precipitation of calcium carbonate from the Scillato springs, documented as bicarbonate-enriched waters due to dissolution of the Madonie mountains carbonate rocks. This deposit is today well represented by the Travertine Cave, essentially constituted by stalactites and stalagmites in which travertine typically appears laminated with alternation of light and dark laminae. Mineralogical analysis have revealed the almost exclusive presence of calcite and observation under the polarized-light microscope showed different textural features, like presence of debris and porous portions, micritic po…
Deep-water stromatolites andFrutexites Maslov from the early and Middle Jurassic of S-Germany and Austria
1993
Despite extensive discussions during the last 20 years stromatolites are still used by many geologists as unequivocal indicators of very shallow-water conditions. We investigated four stratigraphic units from the Lower and Middle Jurassic of southern Germany (Posidonien-Schiefer, Amaltheen-Ton) and of the Northern Calcareous Alps (Adneter Kalk, Klauskalk), which were formerly interpreted as shallow marine sediments by some authors due to the occurrence of stromatolites. Our interpretations of the macro-, micro- and ultrafacies of these sediments are not compatible with shallow-water settings. We therefore propose a deep-marine, aphotic origin of these stromatolites. Former interpretations o…
Microtomographic Quantification of Hydraulic Clay Mineral Displacement Effects During a CO2 Sequestration Experiment with Saline Aquifer Sandstone
2013
We combined a noninvasive tomographic imaging technique with an invasive open-system core-flooding experiment and compared the results of the pre- and postflooded states of an experimental sandstone core sample from an ongoing field trial for carbon dioxide geosequestration. For the experiment, a rock core sample of 80 mL volume was taken from the 629 m Stuttgart Formation storage domain of a saline sandstone aquifer at the CCS research pilot plant Ketzin, Germany. Supercritical carbon dioxide and synthetical brine were injected under in situ reservoir p/T-conditions at an average flow rate of 0.1 mL/min for 256 h. X-ray computed microtomographic imaging was carried out before and after the…
Fossil wood in Middle–Upper Jurassic marine sedimentary cycles of France: relations with climate, sea-level dynamics, and carbonate-platform environm…
1998
Abstract Vegetation, climate, and sea-level oscillations interact in complex ways. Intuition suggests that climatic variations are recorded in geological deposits by both fossil phytoclasts and sediments. Therefore investigation of palaeobotanical remains within a precise sedimentological framework may help to decipher this much-debated interaction. A database of 129 Jurassic (Bathonian–Oxfordian) fossil wood samples from France is used here as a case study. The palaeoenvironment (freshwater swamp, carbonate lagoon, shoreface, argillaceous offshore) and the second-order relative sea-level phases were determined for each datum. There is no correlation between the wood genera distribution and…
One My scale subsidence of carbonate sedimentary bodies and the viscosity of the lower crust
2004
Abstract The possibility of flow of the lower crust under the load produced by carbonate sedimentary accumulations is investigated through the example of the Paris basin during the Middle Jurassic (i.e. Bathonian). Depositional geometries, water depths and sedimentary environments have been estimated and correlated for 164 sites spread over a surface of 380 per 220 km for three successive periods lasting each less than 0.8 My. A signal of relative vertical displacement has been extracted from water-depth and sedimentary thickness. Data have then been interpolated to produce maps of velocity of vertical displacement, sedimentation rate, water depth, and water-depth variation between two peri…
Genesis of the Lower Triassic bonebeds from Gogolin (S Poland): The impact of microbial mats on trapping of vertebrate remains
2017
Three bone-bearing horizons, consis ting of seven bone-bearing beds with fi sh and reptile remains, were recently discovered in the Uppermost Röt (Buntsandstein, Lower Tri assic) peritidal and shallow marine carbonates in the vi- cinity of Gogolin (S Poland). The aim of this study is to reco gnize the genesis and deposi tional environments of the bonebeds. Detailed fi eldwork, microfacies analysis, and SEM-EDS anal ysis reveal that the vertebrate remains occur to a great extent alongside evidence for former microbial activity. The reptile remains represent at least Dactylosaurus and Nothosaurus (Sauropterygia) genera, while the fi sh remains belong to the Chondrichthyes and Actinopterygii. …
Sedimentology and sequence stratigraphy of wedge-top clastic successions: Insights and open questions from the upper Tortonian Terravecchia Formation…
2013
Abstract An up to 1250 m-thick clastic succession, the upper Tortonian Terravecchia Formation (TRV), has been analysed in detail in the middle–late Miocene Scillato wedge-top Basin grown above an already deformed tectonic stack in the northern Sicilian fold-and-thrust belt. The study involved field-based sedimentological and stratigraphic analyses aimed to determine to what extent both the depositional and sequence stratigraphic evolution of the Scillato Basin have been ruled by syn-sedimentary compressional to transpressional tectonics. Widespread intraformational angular unconformities associated with sudden change of palaeocurrents pattern and successive source area shifting suggest that…