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Chronostratigraphy of Plio-Pleistocene Sequences, Offshore Louisiana

SCOTT, ROBERT W., Amoco Production Company, Tulsa, OK

Plio-Pleistocene cool stages correlate with sequence boundaries in the Gulf of Mexico, offshore Louisiana. The cool/warm stages are defined by planktonic foram assemblages in the Vema 16-205 core in the eastern tropical Atlantic. The mean duration of each climatic stage was 230,000 years. These climatic stages were incorporated into a composite standard section with oxygen isotope events, planktonic foraminiferal and nannofossil datums, and magnetostratigraphic events from oceanic core holes: DSDP 502 in the Columbia basin, Caribbean; DSDP 552 on the Rockall Plateau, northeast Atlantic; DSDP 572C in the equatorial Pacific; Vema 28 core 219 on the Solomon Rise, west Pacific; and the Eureka 57 core 135 in DeSoto Canyon, off-shore Florida. These results are similar to those of Martin et l. (1990).

The oxygen isotope events and the paleontologic datums were identified in two exploration wells in the Green Canyon block, offshore Louisiana, and correlated with seismic sequence boundaries. Iterative graphic correlation with the composite standard refines the positions of the tops of the isotope events where data noise makes the pick equivocal providing a precise, high-resolution correlation tool. Each oxygen isotope event represents approximately 31,000 years. The sequences in the Green Canyon area are from 300 m to 800 m thick, and were deposited at rates from 800 to 1500 cm/ka. The duration of the hiatuses at the sequence boundaries range from 27,000 to 200,000 years. These seismic/depositional sequences were deposited during the later parts of the cool stage and the warm climate , which indicate rising sea level to highstand. The ages of the sequence boundaries are approximately 500,000 years, 900,000 years, 1.5 Ma, 2.0 Ma, 2.7 Ma, 3.0 Ma, and 3.75 Ma.


AAPG Search and Discovery Article #91004 © 1991 AAPG Annual Convention Dallas, Texas, April 7-10, 1991 (2009)