--> ABSTRACT: Redeposited Cretaceous Calcareous Nannofossils as a Tool for the Recognition of the Third Order Depositional Highstands in the Middle and Lower Miocene of the Northern Gulf of Mexico, by Mark M. Jiang; #91020 (1995).

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Redeposited Cretaceous Calcareous Nannofossils as a Tool for the Recognition of the Third Order Depositional Highstands in the Middle and Lower Miocene of the Northern Gulf of Mexico

Mark M. Jiang

Redeposited Cretaceous calcareous nannofossils in the middle and lower Miocene sections of the northern Gulf of Mexico vary in occurrence and abundance. The high abundance peaks are found to correspond to the highstands of the third order sequences TB2.1, TB2.3, TB2.4, TB2.5, and TB2.6, and to traditional foram markers Siphonina davisi, Saracenaria schencki, Cibicides opima, Bigenerina humblei, and Globorotalia fohsi robusta, respectively (Jiang, 1993). Because indigenous calcareous nannofossils are normally rare and foram markers are sometimes depressed in these third order depositional highstands, the upper boundaries of these sequences are empirically more easily recognized by their corresponding redeposited Cretaceous coccolith pulses.

These redeposited Cretaceous coccoliths are basically mixed assemblages, but markers of Albian and Cenomanian age are more frequently seen in the pulses corresponding to the middle Miocene Globorotalia fohsi robusta and Bigenerina humblei intervals. Progressively younger Late Cretaceous calcareous nannofossil markers are found in significant numbers in older Miocene sections. The upper Miocene section of the study area normally contains sporadic redeposited Cretaceous calcareous nannofossils that are derived primarily from the Aptian and Neocomian.

This poster illustrates plots of the redeposited Cretaceous coccolith pulses in the middle and lower Miocene of the northern Gulf of Mexico. Wells in this study are from the High Island and Cameron offshore areas, and from Cameron Parish, Louisiana.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995