About This Item
- Full text of this item is not available.
- Abstract PDFAbstract PDF(no subscription required)
Share This Item
The AAPG/Datapages Combined Publications Database
Kansas Geological Society
Abstract
ABSTRACT: An Application of High-Resolution Marine Chemostratigraphy as a Chronostratigraphic Control for "Mid" Cretaceous Oxygen-Isotope Records in Amalgamated Nonmarine Paleosols
Ongoing sequence-stratigraphic reconstructions have led to correlation of Albian-Turonian nonmarine-marine strata in a transect perpendicular to the eastern-margin paleoshoreline of the Western Interior Seaway. In the nonmarine strata, we have developed a high-resolution palynostratigraphy and oxygen-isotope chemostratigraphy from amalgamated Albian–Cenomanian kaolinitic mudrock paleosols in Iowa and Nebraska. Our results suggest that meteorological conditions were stable in the late Albian/early Cenomanian of the midwestern U.S. However, an enrichment in δ18O values from −4.5 to −3.5‰ occurred in the late Albian, followed by a return to more depleted values of −4.5‰.
The sequence stratigraphy was used to tie detailed mid-basin geochemical profiles of %CaCO3,%TOC, HI, and Ol to nearshore geochemical profiles. Correlation of these profiles uses a model for the development of geochemically defined parasequences which provides ~100,000-year resolution. In Kansas, these parasequences interfinger with nonmarine paleosols. Here, oxygen-isotopic profiles generated from the paleosol sphaerosiderites allow us to tie the nonmarine oxygen-isotope chemostratigraphy to the geochemically defined marine parasequence. This approach allow us to better define the amalgamated nonmarine chronostratigraphy and therefore better interpret the paleoclimatological record.
Acknowledgments and Associated Footnotes
1 University of Iowa, Iowa City, Iowa
2 Iowa Department of Natural Resources–Geological Survey Bureau, Iowa City, Iowa
3 University of Iowa, Iowa City, Iowa
Copyright © 2006 by the Kansas Geological Society