نتایج جستجو برای: late paleocene

تعداد نتایج: 196317  

2003
D. V. Kent B. S. Cramer L. Lanci D. Wang R. Van der Voo

We hypothesize that the rapid onset of the carbon isotope excursion (CIE) at the Paleocene/Eocene boundary (V55 Ma) may have resulted from the accretion of a significant amount of 12C-enriched carbon from the impact of a V10 km comet, an event that would also trigger greenhouse warming leading to the Paleocene/Eocene thermal maximum and, possibly, thermal dissociation of seafloor methane hydrat...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2016
Alexander Gehler Philip D Gingerich Andreas Pack

The Paleocene-Eocene Thermal Maximum (PETM) is a remarkable climatic and environmental event that occurred 56 Ma ago and has importance for understanding possible future climate change. The Paleocene-Eocene transition is marked by a rapid temperature rise contemporaneous with a large negative carbon isotope excursion (CIE). Both the temperature and the isotopic excursion are well-documented by ...

ژورنال: :پژوهش های دانش زمین 0
سعیده سنماری دانشگاه بین المللی امام خمینی (ره)، قزوین

در این تحقیق، زیست چینه نگاری سازند پابده در شمال ایلام مورد مطالعه قرار گرفته است. مطالعه نانو فسیلهای آهکی منجر به تشخیص 77 گونه و 29 جنس گردید. مطابق با اولین حضور گونه­های شاخص و گسترش تجمعات فسیلی، بایوزونهای heliolithus kleinpellii zone (np6), discoaster  mohleri zone (np7), heliolithus riedelii zone (np8), discoaster  multiradiatus zone (np9), tribrachiatus contortus zone (np10), discoas...

Journal: :Sedimentary Geology 2023

The Paleogene evolution of the NW margin African Plate (Western External Rif Zone) was studied by means multidisciplinary analyses twenty-one stratigraphic logs, including tectofacies recognition, petro-mineralogical results, and thicknesses analysis. Four intervals were recognized separated three unconformities coarsely aligned with Cretaceous–Paleogene, Eocene–Oligocene Oligocene–Miocene boun...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2009
Jon J Smith Stephen T Hasiotis Mary J Kraus Daniel T Woody

Soil organisms, as recorded by trace fossils in paleosols of the Willwood Formation, Wyoming, show significant body-size reductions and increased abundances during the Paleocene-Eocene Thermal Maximum (PETM). Paleobotanical, paleopedologic, and oxygen isotope studies indicate high temperatures during the PETM and sharp declines in precipitation compared with late Paleocene estimates. Insect and...

Journal: :Alcheringa 2021

Calcareous nannofossil biostratigraphy reveals a continuous depositional record through the Upper Cretaceous‒Paleocene succession in Zagros Basin; southwest Iran (southeastern part of Neo-Tethys), especially Cretaceous‒Paleogene and Danian‒Selandian boundaries. The upper Gurpi Formation lower Pabdeh were investigated. assemblages from these formations are characterized by abundant, diverse mode...

Journal: :Geosphere 2022

Abstract The Cretaceous-Paleogene (K-Pg) contact interval is constrained by vertebrate fossil sites at seven in the Tornillo Group and lies within an 80–100-m stratigraphic section between top of Javelina Formation base “log jam sandstone” marker bed Black Peaks Formation. In western exposures this interval, highest occurrence situ dinosaur specimens lowest Paleocene mammal are separated unusua...

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