An extraterrestrial 3He-based time scale for the Paleocene-Eocene Thermal Maximum (PETM) from Walvis Ridge, IODP Site 1266

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doi: 10.1016/j.gca.2010.03.039
Author(s): Murphy, B. H.; Farley, K. A.; Zachos, J. C.
Author Affiliation(s): Primary:
University of California, Santa Cruz, Earth and Planetary Sciences Department, Santa Cruz, CA, United States
California Institute of Technology, United States
Volume Title: Geochimica et Cosmochimica Acta
Source: Geochimica et Cosmochimica Acta, 74(17), p.5098-5108. Publisher: Elsevier, New York, NY, International. ISSN: 0016-7037 CODEN: GCACAK
Note: In English. Includes appendices. 44 refs.; illus., incl. 1 table
Summary: In the deep-sea, the Paleocene-Eocene Thermal Maximum (PETM) is often marked by clay-rich condensed intervals caused by dissolution of carbonate sediments, capped by a carbonate-rich interval. Constraining the duration of both the dissolution and subsequent cap-carbonate intervals is essential to computing marine carbon fluxes and thus testing hypotheses for the origin of this event. To this end, we provide new high-resolution helium isotope records spanning the Paleocene-Eocene boundary at ODP Site 1266 in the South Atlantic. The extraterrestrial 3He, 3HeET, concentrations replicate trends observed at ODP Site 690 by Farley and Eltgroth (2003). By assuming a constant flux of 3HeET we constrain relative changes in accumulation rates of sediment across the PETM and construct a new age model for the event. In this new chronology the zero carbonate layer represents 35 kyr, some of which reflects clay produced by dissolution of Paleocene (pre-PETM) sediments. Above this layer, carbonate concentrations increase for ∼165 kyr and remain higher than in the latest Paleocene until 234+48/-34kyr above the base of the clay. The new chronology indicates that minimum δ13C values persisted for a maximum of 134+27/-19kyr and the inflection point previously chosen to designate the end of the CIE recovery occurs at 217+44/-31kyr. This allocation of time differs from that of the cycle-based age model of Rohl et al. (2007) in that it assigns more time to the clay layer followed by a more gradual recovery of carbonate-rich sedimentation. The new model also suggests a longer sustained δ13C excursion followed by a more rapid recovery to pre-PETM δ13C values. These differences have important implications for constraining the source(s) of carbon and mechanisms for its subsequent sequestration, favoring models that include a sustained release of carbon after an initial pulse. Abstract Copyright (2010) Elsevier, B.V.
Year of Publication: 2010
Research Program: ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 12 Stratigraphy, Historical Geology and Paleoecology; Atlantic Ocean; C-13/C-12; Carbon; Carbonate sediments; Cenozoic; Chemical composition; Chronostratigraphy; Cosmochemistry; Cosmogenic elements; Extraterrestrial geology; Geochemistry; He-3; Helium; Isotope ratios; Isotopes; Leg 113; Leg 208; Marine sediments; Maud Rise; Noble gases; ODP Site 1266; ODP Site 690; Ocean Drilling Program; Paleocene-Eocene Thermal Maximum; Paleogene; Sediments; South Atlantic; Southern Ocean; Stable isotopes; Stratigraphic boundary; Tertiary; Walvis Ridge; Weddell Sea
Coordinates: S283300 S283200 E0022100 E0022000
S650938 S650937 E0011218 E0011218
Record ID: 2011023879
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands