The late Palaeocene-early Eocene and Toarcian (Early Jurassic) carbon isotope excursions; a comparison of their time scales, associated environmental changes, causes and consequences

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doi: 10.1144/0016-76492006-123
Author(s): Cohen, Anthony S.; Coe, Angela L.; Kemp, David B.
Author Affiliation(s): Primary:
Open University, Department of Earth Sciences, Centre for Earth, Planetary, Space and Astronomical Research, Milton Keynes, United Kingdom
Volume Title: Journal of the Geological Society of London
Source: Journal of the Geological Society of London, 164(6), p.1093-1108. Publisher: Geological Society of London, London, United Kingdom. ISSN: 0016-7649 CODEN: JGSLAS
Note: In English. 141 refs.; illus., incl. chart, sketch map
Summary: 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.
Year of Publication: 2007
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Aliphatic hydrocarbons; Alkanes; C-13/C-12; Carbon; Cenozoic; Climate change; Eocene; Expedition 302; Global change; Global warming; Hydrocarbons; Integrated Ocean Drilling Program; Isotope ratios; Isotopes; Jurassic; Leg 171B; Leg 208; Lower Eocene; Lower Jurassic; Mechanism; Mesozoic; Methane; ODP Site 1051; ODP Site 1262; Ocean Drilling Program; Oceanic anoxic events; Organic carbon; Organic compounds; Paleocene; Paleocene-Eocene Thermal Maximum; Paleoenvironment; Paleogene; Paleogeography; Stable isotopes; Tertiary; Toarcian; Upper Liassic; Upper Paleocene
Record ID: 2007120637
Copyright Information: GeoRef, Copyright 2017 American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States, Reference includes data from The Geological Society, London

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