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Integrated chronostratigraphic calibration of the Oligocene-Miocene boundary at 24.0+ or -0.1 Ma from the CRP-2A drill core, Ross Sea, Antarctica

Gary S. Wilson, Mark Lavelle, William C. McIntosh, Andrew P. Roberts, David M. Harwood, David K. Watkins, Giuliana Villa, Steven M. Bohaty, Chris R. Fielding, Fabio Florindo, Leonardo Sagnotti, Timothy R. Naish, Reed P. Scherer and Kenneth L. Verosub
Integrated chronostratigraphic calibration of the Oligocene-Miocene boundary at 24.0+ or -0.1 Ma from the CRP-2A drill core, Ross Sea, Antarctica
Geology (Boulder) (November 2002) 30 (11): 1043-1046

Abstract

An expanded Oligocene-Miocene boundary interval recovered in the Cape Roberts Project CRP-2A core from beneath the Ross Sea, Antarctica, has yielded a high-resolution integrated chronostratigraphy that has, in turn, enabled a new, more direct, calibration of magnetic polarity and biostratigraphic events. The Oligocene-Miocene boundary interval in the CRP-2A core comprises three approximately 60-m-thick, rapidly deposited (>0.5 m/k.y.) sedimentary sequences (sequences 9, 10, and 11). In sequences 10 and 11, single-crystal, laser-fusion (super 40) Ar/ (super 39) Ar analyses of anorthoclase phenocrysts from two tephra horizons independently calibrate the CRP-2A magnetic-polarity stratigraphy and age model. Sequences 10 and 11 encompass subchron C6Cn.3n, which is dated as 24.3+ or -0.1 to 24.16+ or -0.1 Ma. Sequence 9 is interpreted to encompass subchron C6Cn.2n and the Oligocene-Miocene boundary, which is dated as 24.0+ or -0.1 Ma. These ages are approximately 0.2 m.y. older than those of the geomagnetic polarity time scale calibrated from seafloor-spreading ridges and approximately 0.9-1.3 m.y. older than the newly proposed astronomically calibrated ages. We contend that the discrepancy with the astronomically calibrated ages arises from a mismatch of three 406 k.y. eccentricity cycles or a 1.2 m.y. modulation of obliquity amplitude in the astronomical calibration of the Oligocene-Miocene time scale.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 30
Serial Issue: 11
Title: Integrated chronostratigraphic calibration of the Oligocene-Miocene boundary at 24.0+ or -0.1 Ma from the CRP-2A drill core, Ross Sea, Antarctica
Affiliation: University of Otago, Geology Department, Dunedin, New Zealand
Pages: 1043-1046
Published: 200211
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 28
Accession Number: 2002-079189
Categories: Stratigraphy
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: sect., 1 table, sketch map
S77°00'00" - S77°00'00", E163°41'60" - E163°41'60"
Secondary Affiliation: British Antarctic Survey, GBR, United KingdomNew Mexico Institute of Mining and Technology, USA, United StatesUniversity of Southampton, GBR, United KingdomUniversity of Nebraska, USA, United StatesUniversita di Parma, ITA, ItalyUniversity of California at Santa Cruz, USA, United StatesUniversity of Queensland, AUS, AustraliaIstituto Nazionale di Geofisica e Vulcanologia, ITA, ItalyInstitute of Geological and Nuclear Sciences, NZL, New ZealandNorthern Illinois University, USA, United StatesUniversity of California at Davis, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 200224
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