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Did intense volcanism trigger the first Late Ordovician icehouse?

Geology

By:
, , , , ,
DOI: 10.1130/G30577.1

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Abstract

Oxygen isotopes measured on Late Ordovician conodonts from Minnesota and Kentucky (United States) were studied to reconstruct the paleotemperature history during late Sandbian to Katian (Mohawkian–Cincinnatian) time. This time interval was characterized by intense volcanism, as shown by the prominent Deicke, Millbrig, and other K-bentonite beds. A prominent carbon isotope excursion (Guttenberg δ13C excursion, GICE) postdates the Millbrig volcanic eruptions, and has been interpreted to reflect a drawdown of atmospheric carbon dioxide and climatic cooling. The oxygen isotope record in conodont apatite contradicts this earlier interpretation. An increase in δ18O of 1.5‰ (Vienna standard mean ocean water) just above the Deicke K-bentonite suggests an abrupt and short-lived cooling that possibly initiated a first short-term glacial episode well before the major Hirnantian glaciation. The decrease in δ18O immediately after the mega-eruptions indicates warming before the GICE, and no cooling is shown in the GICE interval. The coincidence of the Deicke mega-eruption with a cooling event suggests that this major volcanic event had a profound effect on Late Ordovician (late Mohawkian) climate.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Did intense volcanism trigger the first Late Ordovician icehouse?
Series title:
Geology
DOI:
10.1130/G30577.1
Volume
38
Issue:
4
Year Published:
2010
Language:
English
Publisher:
GSA
Contributing office(s):
Eastern Geology and Paleoclimate Science Center
Description:
4 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
327
Last page:
330