Early-mid-Cretaceous evolution in Tethyan reef communities and sea level

Conference · Fri Jan 01 04:00:00 EST 1988

OSTI ID:5955689

Scott, R W

The replacement of corals by rudists in Early Cretaceous reefal communities spanned a 30-m.y. period when sea level rose and drowned continental shelves. During this time corals formed communities in the deeper parts of reefs and rudists occupied the shallow, high-energy habitats. By Aptian time rudists dominated reefs that fringed interior shelf basins and corals formed reefs with rudists on the outer shelf margins. By late Albian coral communities had virtually disappeared, presumably because of complex environmental changes and cycles of organic productivity. Two important events of eustatic sea level rise are represented by unconformities separating carbonate depositional sequences on the Arabian platform that correlate with sequence boundaries on the Gulf Coast platform. Graphic correlation techniques test the synchroneity of these events. A composite standard time scale dates these sea level rises at 115.8 Ma and 94.6 Ma; a third, intra-Albian event at 104.3 Ma is present in many places and may also be eustatic. Associated with these sea level rises were apparent changes in ocean water chemistry as evidenced by changes in isotopes and trace elements, where diagenetic effects can be discounted. During this time the climate became more humid and atmospheric CO/sub 2/ increased. The concomitant environmental changes in the oceanic conditions presumably stressed the deeper coral communities on reefs. The emergence of rudists as reef contributors had a profound effect on Late Cretaceous depositional conditions and the development of hydrocarbon reservoirs.

• OSTI ID: 5955689
• Report Number(s): CONF-880301-
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
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& Exploration
03 NATURAL GAS
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& Exploration
AGE ESTIMATION
ARABIAN SEA
ATLANTIC OCEAN
ATMOSPHERIC CHEMISTRY
CARBONATE ROCKS
CARIBBEAN SEA
CATAGENESIS
CHEMISTRY
CNIDARIA
CORALS
CRETACEOUS PERIOD
DEPOSITION
EXPLORATION
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC HISTORY
GEOLOGIC STRUCTURES
GEOLOGY
GULF OF MEXICO
INDIAN OCEAN
ISOTOPE DATING
LEVELS
MESOZOIC ERA
MINERAL RESOURCES
NATURAL GAS DEPOSITS
ORIGIN
PETROLEUM DEPOSITS
PETROLEUM GEOLOGY
REEFS
RESOURCES
ROCKS
SEA LEVEL
SEAS
SEDIMENTARY ROCKS
SURFACE WATERS