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Dinoflagellate and calcareous nannofossil response to sea-level change in Cretaceous-Tertiary boundary sections

Journal Article · · Geology; (United States)
 [1];  [2];  [3]
  1. City Univ. of New York, Flushing (United States)
  2. Geological Survey of Israel, Jerusalem (Israel)
  3. Hamilton College, Clinton, NY (United States)
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Stratigraphic sections in south-central Alabama were studied to test palynological evidence of sea-level change across the Cretaceous-Tertiary boundary. New evidence from both calcareous nannofossils and dinoflagellate cysts places the regional disconformity in Alabama (Type 1 sequence boundary) virtually at the K-T boundary. This suggests that sea-level fall may have contributed to mass-extinction event. Dinoflagellate diversity varies between systems tract components of coastal onlap. This parameter is useful for interpreting sea-level change in this part of the section, because dinoflagellates did not participate in the mass extinction. The iridium spikes in the roadcut near Braggs are of earliest Danian age and correlate in relative magnitude with the lower values reported from directly above the K-T boundary in the Gubbio stratotype section. Iridium was concentrated in marine flooding surfaces in episodes of higher productivity of algal organic matter at the time when the iridium-enriched ocean encroached on the shelf during the first Cenozoic episode of sea-level rise.

OSTI ID:
7004117
Journal Information:
Geology; (United States), Journal Name: Geology; (United States) Vol. 20:2; ISSN GLGYB; ISSN 0091-7613
Country of Publication:
United States
Language:
English

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Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
ALABAMA
ANIMALS
BIOLOGICAL EXTINCTION
BOUNDARY LAYERS
CENOZOIC ERA
CRETACEOUS PERIOD
DEVELOPED COUNTRIES
FORAMINIFERA
FOSSILS
GEOLOGIC AGES
GEOLOGIC HISTORY
GEOLOGIC STRATA
GEOLOGIC STRUCTURES
GEOLOGY
INVERTEBRATES
IRIDIUM COMPOUNDS
LAYERS
LEVELS
MESOZOIC ERA
MICROORGANISMS
NORTH AMERICA
PALYNOLOGY
PROTOZOA
REFRACTORY METAL COMPOUNDS
SARCODINA
SEA LEVEL
SEDIMENTARY BASINS
STRATIGRAPHY
TERTIARY PERIOD
TRANSITION ELEMENT COMPOUNDS
USA