نتایج جستجو برای: depositional sequence
تعداد نتایج: 409161 فیلتر نتایج به سال:
Detection of sedimentary cycles is difficult in fine-grained or homogenous sediments but is a prerequisite for the interpretation of depositional environments. Here we use a new autocorrelation analysis to detect cycles in a homogenous sediment core, E602, from the northern shelf of the South China Sea. Autocorrelation coefficients were calculated for different mean grain sizes at various depth...
U–Pb ages of individual detrital zircon grains from deltaic and turbidite sandstones of the lower to middle Pennsylvanian Haymond Formation (Marathon basin, west Texas) range from 320 Ma to 3 Ga, indicating a mixed provenance broadly similar to that of Ouachita Carboniferous turbidites and related fluvio-deltaic facies of Arkansas–Oklahoma. Differences with the Ouachita assemblage are attribute...
*Correspondence: Davide Tiranti, Hydrology and Natural Hazards, Department of Forecasting Systems, Regional Agency for Environmental Protection of Piemonte, Via Pio VII n. 9, 10135 Turin, Italy e-mail: davide.tiranti@ arpa.piemonte.it A method to predict the most probable flow rheology in Alpine debris flows is presented. The methods classifies outcropping rock masses in catchments on the basis...
Remains of hominoid primates collected by Yale Peabody Museum Geological Survey of Pakistan expeditions to the Siwalik Group rocks of the Potwar Plateau, Pakistan, are described. They consist of facial, gnathic, dental, and postcranial remains of Ramapithecus, Sivapithecus, and Gigantopithecus. They are discussed anatomically and without precise taxonomic attributions. The hominoids come from 2...
We have studied the REE distribution in shallow marine continental platform carbonates belonging to two late Neoproterozoic basins of India. Their REE abundance patterns normalized by chondrite display well defined W-type tetrad effect. Based on chondrite-normalized Gd/Ho, La/Nd ratios, the REE abundance patterns have been classified into three groups. (Y/Ho) and (Y/Dy) concentration ratios ref...
Typhoons have a significant effect on the marine depositional environment and depositional process. In this paper, we used the high-resolution Chirp sonar sub-bottom profiler and radioisotope detection techniques to examine the storm-deposited layer formed in the seawater near the path of Typhoon Saola along the coast of Fujian, China. The thickness of the typhoon-deposited layer acquired using...
Sandbody distribution patterns and controls are the most important foundation for petroleum exploration development, particularly in a lacustrine basin with rapid changes sedimentary environment. To provide sedimentologists geologists around world an analogue sandstone reservoir prediction, facies of fourth member Shahejie Formation (Sha-4 Member) Huimin Depression Bohai Bay Basin were analyzed...
Many negative δ(13)C excursions in marine carbonates from the geological record are interpreted to record significant biogeochemical events in early Earth history. The assumption that no post-depositional processes can simultaneously alter carbonate and organic δ(13)C values towards more negative values is the cornerstone of this approach. However, the effects of post-depositional alteration on...
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