نتایج جستجو برای: cretaceous rocks
تعداد نتایج: 30195 فیلتر نتایج به سال:
The paleobiogeography of the theropod clade Compsognathidae is here reaccessed in order to test the hypothesis of this taxon being adapted specifically to inhabit semi-arid environments. Data about localities where these fossils were collected and their paleoenvironments were gathered from the literature. Compsognathids seem to be found especially in sedimentary deposits known as Fossil Lagerst...
Based on a review of troodontid specimens from the territories of the former Soviet Union, including new discoveries from Uzbekistan, two dental morphotypes can be distinguished among Troodontidae from the Cretaceous of Asia: (1) unserrated teeth, present in Mei from Lujiatun (China; Early Cretaceous: Hauterivian-Barremian), an unnamed taxon from Hövöör (Mongolia; Early Cretaceous: Aptian-Albia...
Abstract The Zagros orogen, formed by the collision of Arabian and Eurasian continental margins, represents one largest richest oil gas provinces in world. fold-thrust belt records convergence along Neotethys suture zone. By coupling field observations, sandstone modal analysis, U-Pb zircon dating, Hf isotopic data from Upper Cretaceous to Pliocene sedimentary succession Neyriz region, this pap...
The Upper Cretaceous Lokoja Formation of southern Niger Basin in Nigeria is a dominantly sandy facies comprising of two distinctive members, the Lokoja and Patti Siltstone. The fluvial sandstone of the Lokoja Sandstone is petrologically defined as dominantly poorly sorted angular to sub-angular, fine to aly skewed, immature lithic arkose to sub-litharenite with a detrital clayey matrix of over ...
The growth rate and composition of cave calcite deposits (speleothems) are often used as proxies for past environmental change. There is, however, the potential for bias in the speleothem record due to seasonal fluctuations in calcite growth and dripwater chemistry. It has been proposed that the growth rate of speleothem calcite in Texas caves varies seasonally in response to density-driven flu...
The Durkan Complex is a key tectonic element of the Makran accretionary prism (SE Iran) and it has been interpreted as representing continental margin succession. We present here multidisciplinary study western Complex, which based on new geological, stratigraphic, biostratigraphic data, well geochemical data volcanic meta-volcanic rocks forming this complex. Our show that complex consists dist...
In most rocks, Natural Remanent Magnetization (NRM) can involve two or more superimposed components. Demagnetizations hopefully result in the separation of these components, which may then be resolved using least-squares regression methods. In a study of Cretaceous redbed sites from Qaidam (China), thermal demagnetization of most specimens revealed 3 rectilinear segments in orthogonal plots, gi...
The trace fossil Gyrochorte is common in Upper Jurassic siliciclastic rocks of the Kachchh Basin, western India. In the Kimmeridgian Katrol Formation, Gyrochorte comosa Heer, 1865 is tied to storm-generated fine-grained sandstones and exhibits an internal structure composed of double arches in cross-section, confirming the three-dimensional nature of the trace fossil and its interpretation as p...
The first broad program of scientific shallow drilling on the U.S. Atlantic continental shelf has delineated rocks of Pleistocene to Late Cretaceous age, including phosphoritic Miocene strata, widespread Eocene carbonate deposits that serve as reflective seismic markers, and several regional unconformities. Two sites, off Maryland and New Jersey, showed light hydrocarbon gases having affinity t...
Brittle deformation can saturate the Earth's crust with faults and fractures in an apparently chaotic fashion. The details of brittle deformational histories and implications on, for example, seismotectonics and landscape, can thus be difficult to untangle. Fortunately, brittle faults archive subtle details of the stress and physical/chemical conditions at the time of initial strain localizatio...
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