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The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract


Volume: 46 (1962)

Issue: 2. (February)

First Page: 269

Last Page: 269

Title: Molluscan Biofacies in Calcareous Sediments of Gulf of Batabano, Cuba: ABSTRACT

Author(s): C. W. Hoskins

Article Type: Meeting abstract

Abstract:

The Gulf of Batabano is a shallow embayment approximately 16,000 square miles in area on the south side of Cuba. It is covered with a veneer of carbonate sediments, and the water is generally no more than 25 or 30 feet deep. Reefs rim the Gulf on the southeast margin.

Calcareous sediments range in composition from clean oolitic sand, composite grain sand, and skeletal sand to a sediment consisting almost entirely of carbonate mud and skeletal debris. Some of these sediment types can be characterized by specific associations of mollusks.

The invertebrate fauna of the Gulf is principally molluscan, and comprises 194 named species and sub-species of gastropods, pelecypods, and scaphopods. Molluscan faunules were used from 119 gravity core and grab samples, which are more or less evenly spaced over the Gulf. Semi-quantitative methods were employed in analyzing the faunal data.

Mollusks are most abundant on areas of carbonate mud along the north margin of the Gulf, particularly in the northeastern part of the Gulf where brackish-water influences are greatest. They are least abundant in high-energy areas along the seaward Gulf margin.

The energy of the water mass and salinity appear to be the two most important environmental factors affecting the distribution of the mollusks. Accordingly, two major ecological molluscan assemblages may be recognized: (1) the Northern Gulf assemblage and (2) the Southeastern Gulf and Gulf Margin assemblage. The Northern Gulf assemblage is best developed in low-energy areas on grassy sediments that contain more than 50 per cent carbonate mud. The Southeastern Gulf and Gulf Margin assemblage is found on relatively clean sandy sediments along the seaward margin of the Gulf, and in the waters of higher energy found in the eastern part of the Gulf. Subordinate faunal associations are recognizable within each assemblage, but these reflect local variations in sediment type, salinity, and ab ndance of marine grasses.

Characteristic species of each of these major assemblages are: (1) Northern Gulf assemblage: Anomalocardia brasilina, Corbula swiftiana, Brachidontes exustus, Alabina sp., Batillaria minima, Tegula fasciata; (2) Southeastern Gulf and Gulf Margin assemblage: Ervilia nitens, Divaricella quadrisulcata, Tellina candeana, Lucina pennsylvanica, Cerithium litteratum, Olivella nivea.

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