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Stable isotopic response to late Eocene extraterrestrial impacts

Aimee E. Pusz; Kenneth G. Miller; James D. Wright; Miriam E. Katz; Benjamin S. Cramer; Dennis V. Kent

Title:
Stable isotopic response to late Eocene extraterrestrial impacts
Author(s):
Pusz, Aimee E.
Miller, Kenneth G.
Wright, James D.
Katz, Miriam E.
Cramer, Benjamin S.
Kent, Dennis V.
Date:
Type:
Articles
Department:
Lamont-Doherty Earth Observatory
Permanent URL:
Part Number:
452
Book/Journal Title:
The Late Eocene Earth—Hothouse, Icehouse, and Impacts
Book Author:
Koeberl, Christian
Publisher:
Geological Society of America
Publisher Location:
Boulder, Colo.
Abstract:
We evaluated the age of two Upper Eocene impact ejecta layers (North American microtektites linked to the Chesapeake Bay impact structure and clinopyroxene [cpx] spherules from the Popigai crater) and the global effects of the associated impact events. The reported occurrence of cpx spherules from the Popigai impact structure at South Atlantic ODP Site 1090 within the middle of magnetochron C16n.1n yields a magnetochronologic age of 35.4 Ma. We generated high-resolution stable isotope records at Sites 1090, 612 (New Jersey slope), and Caribbean core RC9-58 that show: (1) a 0.5‰ δ13C decrease in bulk-carbonate at Site 1090 coincident with the Popigai cpx spherule layer, and (2) a 0.4‰-0.5‰ decrease in deep-water benthic foraminiferal δ13C values across the Popigai impact ejecta layer at Site 612 and core RC9-58. We conclude that the δ13C excursion associated with Popigai was a global event throughout the marine realm that can be correlated to magnetochron C16n.1n. The amplitude of this excursion (~0.5‰) is within the limits of natural variability, suggesting it was caused by a decrease in carbon export productivity, potentially triggered by the impact event(s). North American microtektites associated with the Chesapeake Bay impact occur stratigraphically above the Popigai cpx spherules at Site 612 and core RC9-58. We found no definite evidence of a δ13C anomaly associated with the North American microtektite layer, though further studies are warranted. High-resolution bulk-carbonate and benthic foraminiferal δ18O records show no global temperature change associated with the cpx spherule or North American microtektite layers.
Subject(s):
Physical geography
Publisher DOI:
http://dx.doi.org/10.1130/2009.2452(06)
Item views:
137
Metadata:
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