PALEOENVIRONMENTAL ANALYSIS OF THE HOLOCENE SEDIMENTS OF PIGEON CREEK, SAN SALVADOR, BAHAMAS

The focus of this study is three soft sediment cores (UPC-99-1, UPC-00-1 and UPC-00-2) taken from the northern arm of Pigeon Creek on San Salvador, Bahamas. Pigeon Creek comprises two elongate arms of a tidally-influenced carbonate lagoon bounded by dune ridges.

Core UPC-99-1 is 1.94 m in length and was extracted from the northernmost portion of Pigeon Creek. Cores UPC-00-1 (3.0 m) and UPC-00-2 (1.57 m) were located further to the south. UPC-00-1 and UPC-00-2 were taken in the middle of the lagoon while UPC-99-1 was taken nearer the lagoon's edge. UPC-99-1 and UPC-00-2 both contain Pleistocene bedrock at the base of the core. Peat was found in UPC-99-1 at 1.5m. The peat was C-14 dated to be less than 3500 years old making the sediments Holocene in age. The rate of sedimentation of the core is calculated to be 43 cm/1000yrs.

Within the southern cores, there are two distinct zones. The bottom zone is a peloidal packstone with minor skeletal debris. The coral Porites porites occurs in the lower portion of this zone in UPC-00-2. The upper zone in both cores is also a peloidal packstone but contains more mud, skeletal debris and organic material. Five zones were recognized in UPC-99-1. The base of this core (Zone 1) contains clasts of oolitic Pleistocene bedrock. The next two zones are very muddy (peloidal wackestone to packstones). The peat is found in Zone 2 which is very organic-rich. Zones 4 and 5 are muddy with skeletal material much like the upper zone in UPC-00-1 and UPC-00-2.

A preliminary analysis indicates that the southern portion of the lagoon was less restricted during the early history of Pigeon Creek. Later restriction could be due to the build up of the tidal delta at the mouth of Pigeon Creek. The northern portion of Pigeon Creek was very restricted early on (possibly even an interior lake) and later became as open as the southern portion.