Testing the astronomical time scale for oceanic anoxic event 2, and its extension into Cenomanian strata of the Western Interior Basin (USA)

Research Article| July 01, 2014 Testing the astronomical time scale for oceanic anoxic event 2, and its extension into Cenomanian strata of the Western Interior Basin (USA) Chao Ma; Chao Ma 1Department of Geoscience, University of Wisconsin–Madison, 1215 West Dayton Street, Madison, Wisconsin 53706, USA Search for other works by this author on: GSW Google Scholar Stephen R. Meyers; Stephen R. Meyers † 1Department of Geoscience, University of Wisconsin–Madison, 1215 West Dayton Street, Madison, Wisconsin 53706, USA †E-mail: smeyers@geology.wisc.edu. Search for other works by this author on: GSW Google Scholar Brad B. Sageman; Brad B. Sageman 2Department of Earth and Planetary Sciences, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, USA Search for other works by this author on: GSW Google Scholar Brad S. Singer; Brad S. Singer 1Department of Geoscience, University of Wisconsin–Madison, 1215 West Dayton Street, Madison, Wisconsin 53706, USA Search for other works by this author on: GSW Google Scholar Brian R. Jicha Brian R. Jicha 1Department of Geoscience, University of Wisconsin–Madison, 1215 West Dayton Street, Madison, Wisconsin 53706, USA Search for other works by this author on: GSW Google Scholar GSA Bulletin (2014) 126 (7-8): 974–989. https://doi.org/10.1130/B30922.1 Article history received: 05 May 2013 rev-recd: 17 Jan 2014 accepted: 11 Feb 2014 first online: 08 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Chao Ma, Stephen R. Meyers, Brad B. Sageman, Brad S. Singer, Brian R. Jicha; Testing the astronomical time scale for oceanic anoxic event 2, and its extension into Cenomanian strata of the Western Interior Basin (USA). GSA Bulletin 2014;; 126 (7-8): 974–989. doi: https://doi.org/10.1130/B30922.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract The development of integrated astronomical and radioisotopic time scales from rhythmic strata of the Western Interior Basin (WIB) has played a fundamental role in the refinement of Late Cretaceous chronostratigraphy. In this study, X-ray fluorescence (XRF) core scanning is utilized to develop a new elemental data set for cyclostratigraphic investigation of Cenomanian-Turonian strata in the WIB, using material from the Aristocrat-Angus-12-8 core (north-central Colorado). The XRF data set yields the first continuous 5-mm-resolution analysis of lithogenic, biogenic, and syngenetic-authigenic proxies through the uppermost Lincoln Limestone Member, the Hartland Shale Member, and the Bridge Creek Limestone Member, including oceanic anoxic event 2 (OAE 2). The 40Ar/39Ar ages from ashes in three biozones, including a new age from the Dunveganoceras pondi biozone (uppermost Lincoln Limestone Member), provide geochronologic constraints for the cyclostratigraphic analysis. Astrochronologic testing of the 5-mm-resolution XRF weight percent CaCO3 data via average spectral misfit analysis yields strong evidence for astronomical influence on climate and sedimentation. Results from the Bridge Creek Limestone Member are consistent with the previously published astrochronology from the U.S. Geological Survey #1 Portland core (central Colorado), and identification of an astronomical signal in the underlying Hartland Shale Member now permits extension of the WIB astrochronology into the earlier Cenomanian, prior to OAE 2. High rates of sedimentation in the Angus core during the interval of OAE 2 initiation, as compared to the Portland core, allow recognition of a strong precessional control on bedding development. As a consequence, the new results provide a rare high-resolution chronometer for the onset of OAE 2, and the timing of proposed hydrothermal trace metal enrichment as observed in the 5 mm XRF data. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.