Sedimentology and petrography of dredged carbonate sands from Stocking Island (Bahamas). Implications for meteoric diagenesis and aeolianite formation

Abstract

Piles of carbonate sand dredged onto Stocking Island (Exuma Chain, Bahamas) during World War II are now relatively well-lithified down to a depth of about 80 cm and may contain up to 8% of interstitial calcite cement, a volume comparable to that measured from 1000-yr-old beach ridges elsewhere in the Bahamas. Rates of meteoric diagenetic changes are thus more rapid than previously assessed in this area (∼600 cm 3 of calcite cement produced by m 3 of rock per year). Preservation of hydrodynamic sedimentary structures, footprints, and the lack of aeolian bedforms (e.g. dunes, ripples) on the surface of these sediments further show they have not been reworked by the wind at all. Therefore, the carbonate aeolianites of Holocene and Pleistocene ages forming the bulk of the islands of Bermuda and the Bahamas were likely deposited during relatively dry periods when the effects of meteoric diagenesis were limited. Reduced moisture, along with sediment availability and wind energy, appears as a key player in carbonate aeolianite genesis.