Abstract: Recent and Relict Topography of Boo Bee Patch Reef, Belize, Determined by Diver-Operated Drilling Device
A small patch reef in an area of numerous reservoir-size reefs on the Belizean shelf environment was cored with a newly developed diver-operated drilling device. The patch reef, known as Boo Bee Patch, is about 45 m in diameter and rises 15 m above the carbonate mud and silt bottom on the shelf environment behind an almost continuous reef barrier. Less than 20 percent of the patch is covered by living coral, the rest by uncemented coral rubble, carbonate sand, and sparse sea grass. The sedimentary slope of this flat-topped patch ranges from 35° to almost vertical, where coral covered. Slope sediment consists of coral fragments, primarily staghorn sticks, in a packstone matrix. Corals are absent in the surrounding muddy lagoonal sediments and the transition is abrupt. /P>
Five holes were cored into Pleistocene bedrock on and around Boo Bee Patch. The cores reveal 4 stages of development: (1) subaerial exposure of a Pleistocene "high" having about 6 m of relief, possibly a Pleistocene patch reef; (2) deposition of peat and impermeable terrigenous clay 3 m thick around the high; (3) initiation of carbonate sediment production by corals and algae on the remaining 3 m of hard Pleistocene topography and carbonate mud on the surrounding terrigenous clay; and (4) accelerated organic accumulation on the patch reef. It is estimated that about 20 percent (3 m) of the topography of this patch is inherited from the partly buried Pleistocene high and 80 percent (12.2 m) represents Holocene constructional growth.
Boo Bee Patch is representative of hundreds of patch reefs dotting the Belizean shelf-lagoon platform landward of an almost unbroken reef barrier 160 km long. Shelf-lagoon patch reefs range from a few meters to nearly 2 km in diameter and are as much as 25 m thick. They are porous and permeable, lack early marine cement, and the larger ones are clearly of commercial "reservoir" dimensions. As such, they may serve as models for reef exploration on ancient shelf lagoons.
AAPG Search and Discovery Article #90972©1976 AAPG-SEPM Annual Convention and Exhibition, New Orleans, LA