American Geophysical Union Become an AGU Member
Subscribe to AGU Journals		 AGU Home AGU Publications

Read Full Article (file size: 3107100 bytes)    Cited by

GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS, VOL. 8, Q12002, doi:10.1029/2007GC001784, 2007

On the duration of the Paleocene-Eocene thermal maximum (PETM)

Ursula Röhl

Center for Marine Environmental Sciences (MARUM), Bremen University, Leobener Strasse, D-28359 Bremen, Germany


Thomas Westerhold

Center for Marine Environmental Sciences (MARUM), Bremen University, Leobener Strasse, D-28359 Bremen, Germany


Timothy J. Bralower

Department of Geosciences, Pennsylvania State University, University Park, Pennsylvania 16802, USA


James C. Zachos

Earth and Planetary Sciences Department, University of California, Santa Cruz, California 95064, USA


Abstract

The Paleocene-Eocene thermal maximum (PETM) is one of the best known examples of a transient climate perturbation, associated with a brief, but intense, interval of global warming and a massive perturbation of the global carbon cycle from injection of isotopically light carbon into the ocean-atmosphere system. One key to quantifying the mass of carbon released, identifying the source(s), and understanding the ultimate fate of this carbon is to develop high-resolution age models. Two independent strategies have been employed, cycle stratigraphy and analysis of extraterrestrial helium (HeET), both of which were first tested on Ocean Drilling Program (ODP) Site 690. These two methods are in agreement for the onset of the PETM and initial recovery, or the clay layer (“main body”), but seem to differ in the final recovery phase of the event above the clay layer, where the carbonate contents rise and carbon isotope values return toward background values. Here we present a state-of-the-art age model for the PETM derived from a new orbital chronology developed with cycle stratigraphic records from sites drilled during ODP Leg 208 (Walvis Ridge, Southeastern Atlantic) integrated with published records from Site 690 (Weddell Sea, Southern Ocean, ODP Leg 113). During Leg 208, five Paleocene-Eocene (P-E) boundary sections (Sites 1262 to 1267) were recovered in multiple holes over a depth transect of more than 2200 m at the Walvis Ridge, yielding the first stratigraphically complete P-E deep-sea sequence with moderate to relatively high sedimentation rates (1 to 3 cm/ka, where “a” is years). A detailed chronology was developed with nondestructive X-ray fluorescence (XRF) core scanning records on the scale of precession cycles, with a total duration of the PETM now estimated to be ∼170 ka. The revised cycle stratigraphic record confirms original estimates for the duration of the onset and initial recovery but suggests a new duration for the final recovery that is intermediate to the previous estimates by cycle stratigraphy and HeET.

Received 9 August 2007; accepted 24 October 2007; published 11 December 2007.

Keywords: XRF core scanner; sediment chemistry; cyclostratigraphy; rapid climate change; age model; Paleocene-Eocene thermal maximum.

Index Terms: 1051 Geochemistry: Sedimentary geochemistry; 1616 Global Change: Climate variability (1635, 3305, 3309, 4215, 4513); 4948 Paleoceanography: Paleocene/Eocene thermal maximum; 3036 Marine Geology and Geophysics: Ocean drilling; 4901 Paleoceanography: Abrupt/rapid climate change (1605).

Read Full Article (file size: 3107100 bytes)    Cited by

Citation: Röhl, U., T. Westerhold, T. J. Bralower, and J. C. Zachos (2007), On the duration of the Paleocene-Eocene thermal maximum (PETM), Geochem. Geophys. Geosyst., 8, Q12002, doi:10.1029/2007GC001784.