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Intercalibration of radioisotopic and astrochronologic time scales for the Cenomanian-Turonian boundary interval, Western Interior Basin, USA

Stephen R. Meyers, Sarah E. Siewert, Brad S. Singer, Bradley B. Sageman, Daniel J. Condon, John D. Obradovich, Brian R. Jicha and David A. Sawyer
Intercalibration of radioisotopic and astrochronologic time scales for the Cenomanian-Turonian boundary interval, Western Interior Basin, USA
Geology (Boulder) (November 2011) 40 (1): 7-10

Abstract

We develop an intercalibrated astrochronologic and radioisotopic time scale for the Cenomanian-Turonian boundary (CTB) interval near the Global Stratotype Section and Point in Colorado, USA, where orbitally influenced rhythmic strata host bentonites that contain sanidine and zircon suitable for (super 40) Ar/ (super 39) Ar and U-Pb dating. Paired (super 40) Ar/ (super 39) Ar and U-Pb ages are determined from four bentonites that span the Vascoceras diartianum to Pseudaspidoceras flexuosum ammonite biozones, utilizing both newly collected material and legacy sanidine samples of J. Obradovich. Comparison of the (super 40) Ar/ (super 39) Ar and U-Pb results underscores the strengths and limitations of each system and supports an astronomically calibrated Fish Canyon sanidine standard age of 28.201 Ma. The radioisotopic data and published astrochronology are employed to develop a new CTB time scale, using two statistical approaches: (1) a simple integration that yields a CTB age of 93.89 + or - 0.14 Ma (2sigma ; total radioisotopic uncertainty) and (2) a Bayesian intercalibration that explicitly accounts for orbital time scale uncertainty and yields a CTB age of 93.90 + or - 0.15 Ma (95% credible interval; total radioisotopic and orbital time scale uncertainty). Both approaches firmly anchor the floating orbital time scale, and the Bayesian technique yields astronomically recalibrated radioisotopic ages for individual bentonites, with analytical uncertainties at the permil level of resolution, and total uncertainties below 2 per mil. Using our new results, the duration between the Cenomanian-Turonian and the Cretaceous-Paleogene boundaries is 27.94 + or - 0.16 Ma, with an uncertainty of less than one-half of a long eccentricity cycle.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 40
Serial Issue: 1
Title: Intercalibration of radioisotopic and astrochronologic time scales for the Cenomanian-Turonian boundary interval, Western Interior Basin, USA
Affiliation: University of Wisconsin-Madison, Department of Geoscience, Madison, WI, United States
Pages: 7-10
Published: 20111118
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 24
Accession Number: 2012-009974
Categories: GeochronologyStratigraphy
Document Type: Serial
Bibliographic Level: Analytic
Annotation: With GSA Data Repository Item 2012017; accessed on Dec. 1, 2011
Illustration Description: illus. incl. 1 table, strat. col.
N31°15'00" - N37°00'00", W115°00'00" - W109°00'00"
N37°00'00" - N41°00'00", W109°00'00" - W102°00'00"
N40°00'00" - N43°00'00", W104°04'60" - W95°19'60"
N31°30'00" - N37°00'00", W109°04'60" - W103°00'00"
Secondary Affiliation: Northwestern University, USA, United StatesBritish Geological Survey, GBR, United KingdomU. S. Geological Survey, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201205
Program Name: USGSOPNon-USGS publications with USGS authors
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