Cretaceous/Tertiary boundary event, El Kef Tunesia: a foraminiferal response

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

OSTI ID:6613894

Chi, W R; Keller, G

The Cretaceous/Tertiary boundary extinction event affected benthic communities less than planktonic faunas. Only 9% of benthic species comprising 20% in relative abundance of the total population became extinct, but most species declined in abundance. Only one species, Gavelinella eriksdalensis rapidly increased in abundance through the Danian and Loxostomum and Alabamian dorsoplanata are common in the boundary clay. Two further extinction events of lesser magnitude are observed in the upper A. mayaroensis Zone where 2% of the species go extinct, or 9% of the population, and in the Globigerina engubina Zone where also 2% of the species go extinct or 4% of the population. Significant species abundance changes also accompany these extinction events. Similar stepwise extinction events are also observed in the planktonic foraminifers. Benthic foraminifers indicate that the C/T boundary event was accompanied by a shallowing environment from middle slope to outer shelf. Reducing conditions prevailed during deposition of the boundary clay as suggested by the abundance of pyrite. The authors study of the El Kef section suggests that the observed population turnovers in benthic and planktonic communities could be explained by a sea level fall and/or geotectonically induced changes in oceanic circulation accompanied by temperature and salinity fluctuations. Although they cannot rule out the possibility of impact induced extinction events, have found no evidence of microtektite-like spherules in the boundary clay.

• Research Organization: Princeton Univ., NJ (USA)
• OSTI ID: 6613894
• 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
580100* -- Geology & Hydrology-- (-1989)
ANIMALS
AQUATIC ORGANISMS
ASIA
BENTHOS
BIOLOGICAL EXTINCTION
CENOZOIC ERA
CHALCOGENIDES
CLAYS
CRETACEOUS PERIOD
DEVELOPING COUNTRIES
FORAMINIFERA
FOSSILS
GEOLOGIC AGES
GEOLOGIC HISTORY
INDONESIA
INVERTEBRATES
IRON COMPOUNDS
IRON SULFIDES
ISLANDS
LEVELS
MESOZOIC ERA
MICROORGANISMS
MINERALS
PALEONTOLOGY
PLANKTON
POPULATION DYNAMICS
PROTOZOA
PYRITE
ROCKS
SARCODINA
SEA LEVEL
SEDIMENTARY ROCKS
SULFIDE MINERALS
SULFIDES
SULFUR COMPOUNDS
TERTIARY PERIOD
TRANSITION ELEMENT COMPOUNDS