--> Abstract: Sedimentology and Diagenesis of the Miocene Liuhua Carbonate Platform, Pearl River Mouth Basin, South China Sea, by R. D. Boutell and E. P. Moldovanyi; #91012 (1992).

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ABSTRACT: Sedimentology and Diagenesis of the Miocene Liuhua Carbonate Platform, Pearl River Mouth Basin, South China Sea

BOUTELL, ROBERT D., and EVA P. MOLDOVANYI,* Amoco Production Company, Houston, TX

The depositional and diagenetic history of the Miocene Zhujiang Formation carbonates from the Liuhua platform in the Pearl River Mouth basin has been reconstructed from seismic facies and well data. Two contrasting stages of Liuhua platform development are defined by margin geometries and by regional distribution of prograding, mounded, high-amplitude continuous, and parallel-discontinuous seismic facies. Earliest, or "lower", carbonates developed on a regionally extensive low-angle ramp-style platform resembling the Holocene Persian Gulf complex, while younger, or "upper," carbonates developed on a narrower, high-relief tract similar to the modern Bahamas Bank.

Irregular high-amplitude internal seismic reflectors (termed "chaotic" seismic facies) are evident in upper and lower carbonate platforms, but are absent from adjacent clastic intervals. Association of chaotic facies with truncated reflectors, apparent erosional surfaces, and concave structures analogous to collapse features in karstified terrains, suggests that chaotic seismic facies are the result of subaerial exposure of the carbonates. Abundant vugs and carbon isotopic composition of calcite cements support the model. Increased presence of dolomite in areas of chaotic facies suggests a relationship between subaerial exposure, dolomitization, and chaotic facies. Two principal periods of subaerial exposure, related to eustatic sea level falls, are interpreted from the data and corre pond closely with major changes in platform geometry. The development and diagenesis of the Liuhua carbonate platform parallels that of Miocene reefs in southeast Asia.

 

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)