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Climate of the Past An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/cp-2017-74
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
14 Jun 2017
Review status
This discussion paper is under review for the journal Climate of the Past (CP).
Synchronizing early Eocene deep-sea and continental records – new cyclostratigraphic age models from the Bighorn Basin Coring Project
Thomas Westerhold1, Ursula Röhl1, Roy Wilkens2, Philip D. Gingerich3, Will Clyde4, Scott Wing5, Gabe Bowen6, and Mary Kraus7 1MARUM – University of Bremen, Bremen, 28359, Germany
2Hawaii Institute of Geophysics & Planetology, University of Hawaii, Honolulu, HI, 96822, USA
3Museum of Paleontology, University of Michigan, Ann Arbor, Michigan 48109-1079, USA
4Department of Earth Sciences, University of New Hampshire, 56 College Rd., Durham, NH 03824, USA
5Department of Paleobiology, P.O. Box 37012; National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20013, USA
6Department of Geology & Geophysics, University of Utah, Salt Lake City, UT, 84112, USA
7Department of Geological Sciences, University of Colorado at Boulder, UCB 399; Boulder, CO80309, USA
Abstract. A consistent stratigraphic framework is required to understand the effect of major climate perturbations of the geological past on both marine and terrestrial ecosystems. Transient global warming events in the early Eocene, 56–54 Ma ago, show the impact of large scale input of carbon into the ocean-atmosphere system. Here we provide the first time-scale synchronization of continental and marine deposits spanning the Paleocene-Eocene Thermal Maximum (PETM) and the interval just prior to the Eocene Thermal Maximum 2 (ETM-2). Cyclic variations in geochemical data come from continental drill cores of the Bighorn Basin Drilling Project (BBCP, Wyoming, USA) and from marine deep-sea drilling deposits retrieved by the Ocean Drilling Program (ODP). Both are dominated by eccentricity modulated precession cycles that are used to construct a common cyclostratigraphic framework. Integration of age models results in a revised astrochronology for the PETM in deep-sea records that is now generally consistent with independent 3He age models. The duration of the PETM is estimated at ~ 200 kyr for the CIE and ~ 120 kyr for the pelagic clay layer. A common terrestrial and marine age model shows a concurrent major change in marine and terrestrial biotas ~ 200 kyr before ETM-2. In the Bighorn Basin, the change is referred to as Biohorizon B, and it represents a period of significant mammalian turnover and immigration, separating the upper Haplomylus-Ectocion Range Zone from the Bunophorus Interval Zone and approximating the Wa-4–Wa-5 land mammal zone boundary. In sediments from ODP Site 1262 (Walvis Ridge), major changes in the biota at this time are documented by the radiation of a 2nd generation of apical spine-bearing sphenoliths species (e.g., S. radians and S. editus), the emergence of T. orthostylus, and the marked decline of D. multiradiatus.

Citation: Westerhold, T., Röhl, U., Wilkens, R., Gingerich, P. D., Clyde, W., Wing, S., Bowen, G., and Kraus, M.: Synchronizing early Eocene deep-sea and continental records – new cyclostratigraphic age models from the Bighorn Basin Coring Project, Clim. Past Discuss., https://doi.org/10.5194/cp-2017-74, in review, 2017.
Thomas Westerhold et al.
Thomas Westerhold et al.

Data sets

Synchronizing early Eocene deep-sea and continental records from the Bighorn Basin Coring Project. Unpublished dataset #875685
T. Westerhold
https://doi.pangaea.de/10.1594/PANGAEA.875685
Thomas Westerhold et al.

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Short summary
Here we present a high-resolution time-scale synchronization of continental and marine deposits for one of the most pronounced global warming events, the Paleocene-Eocene Thermal Maximum, that occurred 56 million years ago. New high-resolution age models for the Bighorn Basin Coring Project (BBCP) drill cores help to improve age models for climate records from deep-sea drill cores and for the first time point to a concurrent major change in marine and terrestrial biotas 54.25 million years ago.
Here we present a high-resolution time-scale synchronization of continental and marine deposits...
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