High resolution stratigraphy at the Cenomanian/Turonian boundary and the timing of paleoceanographic events

Conference · Tue Jan 01 04:00:00 EST 1985 · Geol. Soc. Am., Abstr. Programs; (United States)

OSTI ID:6649789

Bralower, T J; Diner, R

The Cenomanian/Turonian (Mid-Cretaceous) boundary interval is a time of widespread deposition of organic carbon-rich sediments, marked enrichment of deltaC/sup 13/ measured in carbonates and quite dramatic plankton extinctions. Calcareous nannofossil biostratigraphy has been studied in boundary sections from Arizona, Colorado, Manitoba, DSDP Sites 549 and 551 and several sections from Italy. A consistent set of twelve first and last appearance datum levels have been determined yielding a resolution of approximately 100,000 years. This stratigraphy allows a precise comparison of the timing of the various black shale layers in DSDP and European land section and the carbon isotopic shift as observed in the Western Interior Basin. The single black shale horizons found at DSDP Sites 549 and 551 appear to be exactly contemporaneous with those at the Cismon and Monte Petrano sections of Italy. Nannofossils observed in the black shale at Site 549 indicate that it was deposited shortly prior to the carbon isotopic shift. This timing supports the conclusion of other studies that the carbon shift was a direct result of massive organic carbon removal from the oceanic system. The authors stratigraphic study also indicates that the black shales record an anoxic event in the latest Cenomanian which lasted approximately 100,000 years. The oceanic carbon reservoir, however, required three times this duration to return to its steady state.

• Research Organization: Scripps Institution of Oceanography, La Jolla, CA (USA)
• OSTI ID: 6649789
• Report Number(s): CONF-8510489-
• Conference Information: Journal Name: Geol. Soc. Am., Abstr. Programs; (United States) Journal Volume: 17
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580400* -- Geochemistry-- (-1989)
580500 -- Oceanography-- (1980-1989)
AQUATIC ORGANISMS
ARIZONA
ATLANTIC OCEAN
BIOLOGICAL EXTINCTION
BITUMINOUS MATERIALS
BLACK SHALES
CANADA
CARBON 13
CARBON ISOTOPES
CARBONACEOUS MATERIALS
CHATTANOOGA FORMATION
CHEMICAL ANALYSIS
CHEMICAL COMPOSITION
CHEMISTRY
COLORADO
CRETACEOUS PERIOD
ENERGY SOURCES
EUROPE
EVEN-ODD NUCLEI
FEDERAL REGION IX
FEDERAL REGION VIII
FOSSIL FUELS
FOSSILS
FUELS
GEOCHEMISTRY
GEOLOGIC AGES
GEOLOGIC FORMATIONS
GEOLOGY
ISOTOPE RATIO
ISOTOPES
ITALY
LIGHT NUCLEI
MANITOBA
MATERIALS
MESOZOIC ERA
NORTH AMERICA
NUCLEI
OCEANOGRAPHY
OIL SHALES
PLANKTON
QUANTITATIVE CHEMICAL ANALYSIS
SEAS
SEDIMENTS
STABLE ISOTOPES
STRATIGRAPHY
SURFACE WATERS
USA
WESTERN EUROPE