Response of larger benthic foraminifera to the Paleocene-Eocene thermal maximum and the position of the Paleocene/Eocene boundary in the Tethyan shallow benthic zones: Evidence from south Tibet

The Paleocene-Eocene thermal maximum (PETM) is one of the most pronounced global warming events in the Cenozoic. This event was associated with a large negative carbon isotope excursion (CIE) and with major changes in the atmosphere hydrosphere and biosphere. However how the larger benthic foraminif...

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Bibliographic Details
Published in:GSA Bulletin
Main Authors: Zhang, Qinghai, Willems, Helmut, Ding, Lin, Xu, Xiaoxia
Format: Report
Language:English
Published: GEOLOGICAL SOC AMER 2019
Subjects:
CARBON-ISOTOPE EXCURSION
SPATIOTEMPORAL PATTERNS
STABLE-ISOTOPES
METHANE HYDRATE
EVOLUTION
CLIMATE
OCEAN
BIOSTRATIGRAPHY
TEMPERATURE
COLLISION
Geology
Geosciences
Multidisciplinary
Methane hydrate
Online Access:http://ir.nigpas.ac.cn/handle/332004/16158
http://ir.nigpas.ac.cn/handle/332004/16159
https://doi.org/10.1130/B31813.1
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Summary:The Paleocene-Eocene thermal maximum (PETM) is one of the most pronounced global warming events in the Cenozoic. This event was associated with a large negative carbon isotope excursion (CIE) and with major changes in the atmosphere hydrosphere and biosphere. However how the larger benthic foraminifera (LBFs) in the shallow Tethyan Ocean responded to the PETM remains controversial. In this study we investigate two shallow-marine LBF-rich carbonate sections from south Tibet aiming to locate the position of the Paleocene/Eocene (P/E) boundary in the Tethyan shallow benthic zones (SBZs) and to examine the response of the LBFs to the PETM. Carbon isotope compositions of bulk carbonate were measured to constrain the stratigraphic position of the CIE onset marking the P/E boundary in the sections and the LBFs were studied in rock thin sections in order to assess their biostratigraphy and to construct the SBZs. The combination of the carbon isotope data and constructed SBZs shows that the P/E boundary is located within SBZS not at the SBZ4/SBZ5 transition as proposed in the Western Tethyan domain. At the P/E boundary no evident compositional change in LBF assemblages can be observed. However a major compositional change in LBF assemblages occurs in the CIE recovery characterized by the sudden disappearance of Miscellanea Ranikothalia Setia Orbitosiphon and the initial dominance of porcellaneous-walled Alveolina and Orbitolites together with small miliolids and rotaliids. We tentatively speculate that this compositional change in LBF assemblages may be related to a eutrophication event likely resulting from intensified continental weathering during the CIE recovery of the PETM.

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