نتایج جستجو برای: lower paleogene

تعداد نتایج: 692919  

Journal: :Journal of South American Earth Sciences 2023

The rise of the Andes and associated propagation retroarc foreland basin during Mesozoic Cenozoic in western South America shaped paleogeography paleoenvironmental settings Western Amazonia. Much attention has been paid to Neogene evolution Amazonian Basin, but few studies have investigated detail paleoenvironments Amazonia Paleogene. We present a multi-proxy study that includes new biostratigr...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2011
Nicholas R Longrich Tim Tokaryk Daniel J Field

The effect of the Cretaceous-Paleogene (K-Pg) (formerly Cretaceous-Tertiary, K-T) mass extinction on avian evolution is debated, primarily because of the poor fossil record of Late Cretaceous birds. In particular, it remains unclear whether archaic birds became extinct gradually over the course of the Cretaceous or whether they remained diverse up to the end of the Cretaceous and perished in th...

2011
Reinhard Kozdon D. Clay Kelly Noriko T. Kita John H. Fournelle John W. Valley

[1] Cool tropical sea surface temperatures (SSTs) are reported for warm Paleogene greenhouse climates based on the dO of planktonic foraminiferal tests. These results are difficult to reconcile with models of greenhouse gas–forced climate. It has been suggested that this “cool tropics paradox” arises from postdepositional alteration of foraminiferal calcite, yielding erroneously high dO values....

2013
Intizar H. Khan William C. Clyde

Analysis of lithofacies, paleoflow directions, and sandstone petrography of upper Paleocene-lower Eocene paralic and continental sediments exposed along the transpressional suture zone of the western margin of the Indian plate indicate that the process of deformation and uplift of the carbonate shelf in this area had started by late Paleocene time. This tectonic uplift and deformation is docume...

2014
Ellen Thomas Laia Alegret Eustoquio Molina

We studied Upper Cretaceous and Lower Paleogene benthic foraminifera from the Agost section (southeastern Spain) to infer paleobathymetrical changes and paleoenvironmental turnover across the Cretaceous/Paleogene (K/P) transition. Benthic foraminifera indicate uppermost bathyal depths at Agost during the Abathomphalus mayaroensis Biochron (from about 400 kyr before the K/P boundary) through the...

2003
Laia Alegret Eustoquio Molina Ellen Thomas

We studied Upper Cretaceous and Lower Paleogene benthic foraminifera from the Agost section (southeastern Spain) to infer paleobathymetrical changes and paleoenvironmental turnover across the Cretaceous/Paleogene (K/P) transition. Benthic foraminifera indicate uppermost bathyal depths at Agost during the Abathomphalus mayaroensis Biochron (from about 400 kyr before the K/P boundary) through the...

Journal: Geopersia 2019

This study presents calcareous nannofossils biostratigraphy of the Campanian‒Danian interval at the Gurpi Formation in the southwest of Ilam Province, in the Zagros Basin. The studied sequence of the Gurpi Formation mainly consists of marly shale and limestones. The thickness of Gurpi Formation was measured as approximately 230 m. Forty-five species belonging to twenty-eight genera were recorde...

2014
Jacob A. McCartney Nancy J. Stevens Patrick M. O’Connor

The extant snake fauna has its roots in faunal upheaval occurring across the Paleogene-Neogene transition. On northern continents, this turnover is well established by the late early Miocene. However, this transition is poorly documented on southern landmasses, particularly on continental Africa, where no late Paleogene terrestrial snake assemblages are documented south of the equator. Here we ...

Journal: :Acta Geologica Polonica 2023

The Szamotuly Graben covers the southernmost part of Permo-Mesozoic Poznan–Szamotuly Fault Zone. Along this regional discontinuity there are several salt structures, including diapir, over which an extensional graben formed in Paleogene and Neogene. is located north Poznan central-western Poland, NW–SE-trending, ~20 km long, 3–5.5 wide, up to 160 m deep. It filled with Lower Oligocene Neogene s...

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