Organic-walled microplankton paleoecology and biostratigraphy of the Upper Cretaceous Ripley Formation, southwestern Georgia

dc.contributor.authorDegnan, Keith Terenceen
dc.contributor.departmentGeological Sciencesen
dc.description.abstractThis study documents the occurrence of dinoflagellate, chlorophyte, and acritarch cysts from the Upper Cretaceous upper Cusseta, Ripley, and lower Providence Formations in the USGS Fort Gaines core, drilled in Clay County, Georgia. A total of 75 taxa were identified, consisting of 36 genera, 61 species, and 5 subspecies of dinoflagellates, 3 genera and 4 species of chlorophytes, 3 genera and 4 species of acritarchs, and 1 problematical protozoan. 15 of these taxa are unpublished. The study's cyst assemblage was statistically analyzed to ascertain paleoecologic patterns. The results from cluster analysis and detrended correspondence analysis indicate the presence of four cyst associations. The <i>Deflandrea pannucea</i> association is interpreted as indicative of low salinity related to nearby river discharge. The <i>Deflandrea</i> sp. A association is confined to the inner shelf. The <i>Exochosphaeridium bifidum</i> and <i>Glaphyrocysta reticulosa</i> associations alternate under normal marine conditions. The associations correlate well with observed lithologies and lithologic change. Comparison of this study's assemblage with other Late Cretaceous assemblages provides limited information, since many biostratigraphically-important species are not present in this study. However, comparisons with Wilson's (1974), Benson's (1976), and Firth's (1984) zonations suggest a Lower Maastrichtian age for all strata in this study.en
dc.format.extentvii, 200 leavesen
dc.publisherVirginia Polytechnic Institute and State Universityen
dc.relation.isformatofOCLC# 16653401en
dc.rightsIn Copyrighten
dc.subject.lccLD5655.V855 1987.D43en
dc.subject.lcshDinoflagellates, Fossilen
dc.subject.lcshGeology -- Georgia -- Clay Countyen
dc.subject.lcshPlankton, Fossilen
dc.titleOrganic-walled microplankton paleoecology and biostratigraphy of the Upper Cretaceous Ripley Formation, southwestern Georgiaen
dc.type.dcmitypeTexten Sciencesen Polytechnic Institute and State Universityen


Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
19.59 MB
Adobe Portable Document Format