COMPREHENSIVE MODEL FOR MODERN LAGOONAL PATCH REEF SYSTEMS IN DISCOVERY BAY, JAMAICA, AND APPLICATION TO INTERPRETING ANCIENT PALEOZOIC BIOHERMS

Marie Maher

Baylor University; Department of Geology

Waco, Tx

[email protected]

Modern reefs have served as the basis for interpretation of ancient carbonate buildups for more than 100 years. Carbonate organic structures, primarily mounds and bioherms, have been associated with the modern forereef environment of fringing or barrier reefs. However, data collected over the past thirty years suggests that lagoonal patch reefs may serve as a more useful model for Paleozoic bioherms than the traditionally used fringing or barrier reef model.

Beginning in the summer of 1974, preliminary observations were made of the lagoonal patch reefs in Discovery Bay, Jamaica. Surveys suggested that lagoonal patch reefs contain a unique biotic zonation that is characteristic of greater depths on the forereef of the fringing-barrier reef model. Geologists have essentially ignored lagoonal patch reefs in bioherm studies because they are hosted on a muddy substrate in areas of low visibility. This unique mud association results in the use of lagoonal patch reefs as models for many Paleozoic bioherms of economic importance.

This project seeks to examine, in detail, modern lagoonal patch reefs in Discovery Bay, Jamaica, with particular attention to documenting historical bathymetric changes, biotic zonation, and sedimentological history. A comprehensive model will be created in the hopes of providing a greater understanding of the genesis of ancient bioherms and their potential as hydrocarbon reservoirs. The similarity of lagoonal reefs to ancient Paleozoic carbonate bioherms may increase understanding of facies relationships in oil and gas exploration.

AAPG Search and Discovery Article #90060©2006 AAPG Foundation Grants-in-Aid