DEPOSITIONAL HISTORY AND COASTAL EVOLUTION OF SALT PONDS, SOUTHWEST PUERTO RICO

This study recovered seven push cores from the southwestern edge of a coastal salt pond in Cabo Rojo, Puerto Rico, to examine its development over the mid to late Holocene. Because salt ponds are relatively undisturbed sediment sinks, stratigraphic analyses of these features can provide a unique record of recent depositional changes. Sedimentary facies of core material are defined based on a combination of characteristics including, bulk carbon composition, grain size, mineral composition and radiometric age. Thus far, three different sedimentary facies have been consistent throughout the cores. In stratigraphic order from bottom to top these are a carbonate mud with halimeda plates, an organic-rich mud with woody (mangrove) material and an upper laminated microbial mat. The most prominent feature of the cores is an abrupt transition from carbonate mud to organic-rich mud, dated to around 1960 cal yr BP. This transition is interpreted as a change from shallow marine backbarrier lagoon to an enclosed coastal salt pond that may have been related to a regression from the mid Holocene high stand. This study will shed light on the mechanisms of coastal dynamics (e.g., barrier development and history) and by using our combined approach, we will highlight the complex development of this coastal salt pond in response to sea level changes.