Current Research
The Cretaceous Chronostratigraphic Database - CRETCSDB1 is a compilation of more than 3400 fossil taxa and marker beds calibrated to a numerical mega-annum scale (Fig. 1). These events are integrated from numerous published worldwide sections that span from the Jurassic/Cretaceous boundary to the Cretaceous/Paleogene boundary (Appendix 1). The numerical ages of the ranges have been interpolated by graphic correlation of the sections listed in (Appendix 2). The ranges of first and last occurrences (FO/LO) are presented in mega-annums calibrated to Global Stratotype and Section Points or to standard reference sections where GSSPs are not yet designated (Appendix 3). The ages of the taxa and marker beds are preliminary because ranges of some taxa are constrained by very few sections so that their ages may extend as new sections are added to the database. (read more)
We announce the completion of the Cretaceous Chronostratigraphic Database - CRETCSDB.1, that integrates ammonites, foraminifers, nannofossils, dinoflagellates, and other selected bioevents with magnetochrons, radiometrically dated beds, geochemical events, and sequence stratigraphic horizons in a numeric age scale. More than 150 locales and more than 3000 events compose this database. The middle to Late Cretaceous part of this database is available on this website as MIDK42, which was prepared for the upcoming SEPM Special Publication 91 on Cretaceous Oceanic Redbeds. The complete database will be uploaded to this site soon.
Dr. Scott was involved in planning the final meeting of IGCP 555 "Rapid Environmental/Climate Change in the Cretaceous Greenhouse World: Ocean-Land Interactions." This international collaboration between Chinese and Western geologists will meet at the October 2010 Geological Society of America convention in Denver. The completely cored Cretaceous lacustrine section in the Songliao Basin, China, will be compared to the Western Interior mixed marine to brackish epicontinental seaway.
The collaborative study of the middle Cretaceous section in the U.S. Western Interior funded by the National Science Foundation was completed in 2005. A number of papers report the results and can be downloaded from this website. The latest Albian-earliest Cenomanian multiple sea-level rises deposited brackish to marine lithofacies and shoreline trends are delineated by palynofacies. The sequence stratigraphic framework of this interval in Montana, Wyoming, Colorado, western Kansas, western Oklahoma, and northeastern New Mexico correlate with the upper part of the Washita Group in North Texas. One unexpected result is that the cosmopolitan dinoflagellates correlate the Albian-Cenomanian boundary defined in France with the Clay Spur Bentonite Bed, which was dated at 97.17+/-0.69 Ma by J.D. Obradovich.
Collaboration with Dr. Carlos Gonzalez-Leon at the Instituto de Geologia, Hermosillo, Mexico, resulted in detailed correlation of the Aptian-Albian section in Sonora with that in Arizona and Texas. A new radiometric date is related to Upper Aptian ammonites.
Study of cores of the Albian section at the Texas shelf margin and of Permian sections continues.
RUDISTS OF TIBET AND TARIM BASIN, CHINA: Significance Of Requieniidae Phylogeny
ABSTRACT—Rudists are a principal biotic component of Cretaceous carbonates in Tibet and in the Western Tarim Basin. Barremian to Maastrichtian carbonate units are widespread on the northern margin of the Indian Plate and in Tethyan tectonic slices that were welded onto Eurasia in successive stages during the Late Cretaceous and Paleogene. In far northwestern Tibet, Barremian-Cenomanian endemic rudists and cosmopolitan orbitolinid foraminifera occupied isolated carbonate platforms in the eastern Tethys. Rudists, corals, and stromatoporoids composed bioherms up to 10 m thick and several kilometers in lateral extent. A unique endemic requieniid rudist, Rutonia, is compared to morphologically similar but older, less derived genera. (read more)