Progressive Shoaling of Plio-Pleistocene Margins Little Bahama Bank
Study of four cores taken across Little Bahama Bank has revealed a facies evolution characterized by general shoaling of the bank margins. Following flooding of an early Pliocene(?) shallow bank margin, a 40 to 60 m (130 to 195 ft) deep fore-reef slope, was buried by a marginal reef and capped by bedded, non-skeletal grainstones. This shoaling sequence represents a change in bank character from a flooded, flat-topped bank with sloping margins, through an atoll-like stage of raised reef rims and deeper interior, to a shallow, flat-topped configuration similar to the present.
Three additional findings include: (I) identification of a major bankwide change from predominantly skeletal to non-skeletal deposition; (2) addition of a third, deeper style of deposition to the previously known “awash” and atoll-like stages of the Bahamas; and (3) discovery of a bankwide body of young, well-developed dolomite in the shallow subsurface of western Little Bahama Bank.
Figures & Tables
Carbonate buildups have long been a focus of intense geological study. An underlying reason is the importance of carbonate buildups as significant hydrocarbon reservoirs. This core workshop is intended to provide a “hands on” look at the subsurface geologic record created by carbonate buildups with emphasis on lithofacies, stratigraphy of buildups and their surrounding deposits, geometry, “reef”-building and sediment-producing organisms, and diagenesis and porosity evolution