The Late Palaeocene - Early Eocene and Toarcian (Early Jurassic) carbon isotope excursions: A comparison of their time scales, associated environmental changes, causes and consequences

Cohen, A. S. and Coe, A. L. and Kemp, D. B. (2007) The Late Palaeocene - Early Eocene and Toarcian (Early Jurassic) carbon isotope excursions: A comparison of their time scales, associated environmental changes, causes and consequences. Journal of the Geological Society, 164 (6). pp. 1093-1108. DOI 10.1144/0016-76492006-123

[img] PDF
Kemp_J_GeolSoc_164.pdf
Restricted to Registered users only

Download (493kB)

Abstract

Although the Earth's environment is constantly changing, there have been a few unusual episodes over the last c. 200 Ma when change was extreme in terms of its rapidity, severity, long-lasting consequences and unpredictability. The geochemical and biotic records for two of these episodes, the Palaeocene-Eocene thermal maximum and the Toarcian Oceanic Anoxic Event (Early Jurassic), possess many significant similarities. Each event was associated with a major carbon isotope excursion, significant levels of biotic extinctions, severe global warming, an enhanced hydrological cycle, and evidence for widespread seawater anoxia. Both carbon isotope excursions can be subdivided into distinct stages with broadly similar characteristics and durations; based on a detailed comparison, the Palaeocene-Eocene thermal maximum may have been an incipient Oceanic Anoxic Event. The geochemical and biotic changes during these two events are most readily explained by the abrupt, large-scale dissociation of methane hydrate that followed a period of more gradual environmental change linked to the emplacement of a large igneous province. Carbon release rates at those times were of the same order of magnitude as the current anthropogenic release rate of carbon to the atmosphere, indicating that ancient events such as these may usefully serve as analogues for present-day environmental change.

Item Type: Article
Subjects: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Divisions: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Journal or Publication Title: Journal of the Geological Society
Volume: 164
Page Range: pp. 1093-1108
Identification Number: 10.1144/0016-76492006-123
Depositing User: Sarah Humbert
Date Deposited: 23 Jan 2010 00:41
Last Modified: 23 Jul 2013 09:56
URI: http://eprints.esc.cam.ac.uk/id/eprint/1306

Actions (login required)

View Item View Item

About cookies