Pleistocene Shallowing-Upward Sequences in New Providence, Bahamas: Signature of High-Frequency Sea-Level Fluctuations in Shallow Carbonate Platforms

Abstract

ABSTRACT Examination of several closely spaced cores from western New Providence, Bahamas, shows a classic shoaling-upward progression of facies. Refined age constraints from magnetostratigraphy indicate that since the Brunhes/Matuyama boundary (0.78 Ma), only three sea-level highstands have flooded this part of the platform. The reefal-skeletal-oolitic-peloidal facies sequence, probably representing deposition during fourth-order highstands, show lateral facies changes and perhaps regional climatic influences. This skeletal-to-nonskeletal transition is common in other Bahamian platform records, and appears to be youngest near the edges of the platform. Estimates of sea level during the reversed-polarity Matuyama, without subsidence corrections, show that it reached within about 10 m below pre ent sea level. During the Brunhes chron, at least one highstand came to within 6-7 m of present mean sea level. The uppermost part of a core, containing beach facies, is now about 6 m above sea level and is thought to represent the 0.13 Ma sea-level event.