Foraminiferal and calcareous nannofossil paleoecology across the Cenomanian/Turonian boundary in the western interior of North America
The Cenomanian-Turonian boundary is noted by a global positive excursion in the carbon isotopic signature. Sediments deposited during this interval in Europe are rich in organic carbon this interval in Europe are rich in organic carbon. These data suggest unusually high productivity which should be expressed within the composition of the plankton. The authors have examined samples from three sections in the Western Interior Seaway from Manitoba, Colorado, Arizona, that represent nearshore and offshore calcareous litho facies. They analyzed the foraminifera and calcareous nannofossils to determine how biostratigraphic and paleoecologic events affected the makeup of faunal and floral assemblages. The extinction of the calcareous nannofossil P. albianus occurs at the first appearance of the planktonic foraminifer W. archeocretacea, which marks the base of the boundary interval. Nearshore foraminiferal assemblages that include planktonic taxa, characteristically contain a benthic fauna composed of both arenaceous and calcareous species. During these blooms though, planktonics disappear as does the calcareous component of the benthic fauna, most notably the nodosariids. Co-occurring shifts in the relative abundance of the planktonic foraminifera and the calcareous nannofossils in the more offshore facies are also evident. Finally when the authors compare the faunal data with the record of carbon and oxygen isotopes, they find that the timing of the biostratigraphic events already described is coincident with the positive excursion of the carbon isotope.
- Research Organization:
- Univ. of Colorado, Boulder (USA)
- OSTI ID:
- 6874418
- Report Number(s):
- CONF-8510489-
- Journal Information:
- Geol. Soc. Am., Abstr. Programs; (United States), Journal Name: Geol. Soc. Am., Abstr. Programs; (United States) Vol. 17; ISSN GAAPB
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
580400* -- Geochemistry-- (-1989)
ANIMALS
AQUATIC ORGANISMS
ARIZONA
CANADA
CARBON ISOTOPES
CHEMICAL ANALYSIS
CHEMICAL COMPOSITION
CHEMISTRY
COLORADO
FEDERAL REGION IX
FEDERAL REGION VIII
FORAMINIFERA
FOSSILS
GEOCHEMISTRY
GEOLOGY
INVERTEBRATES
ISOTOPE RATIO
ISOTOPES
LITHOLOGY
MANITOBA
MICROORGANISMS
NORTH AMERICA
PALEONTOLOGY
PLANKTON
PRODUCTIVITY
PROTOZOA
QUANTITATIVE CHEMICAL ANALYSIS
ROCKS
SARCODINA
SEDIMENTARY ROCKS
STRATIGRAPHY
USA