SPELEOTHEM-BASED PALEOCLIMATE RECONSTRUCTION FOR PUERTO RICO, CARIBBEAN REGION

In order to better understand and reconstruct the climate of the Caribbean region, stalagmites from two caves in Puerto Rico have been collected. The speleothems were sampled from the northern karst of the island, which provides much of Puerto Rico's freshwater and contains the island's most extensive cave systems. The aim of this study is to provide a thorough, speleothem-based paleoclimate record for the island. Because of its geographic location the island's climate is influenced and controlled by different global coupled ocean-atmosphere phenomena such as the variable intensity of El Niño Southern Oscillation, changes in the relative position of the Intertropical Convergence Zone and variations in the North Atlantic Oscillation.

Precipitation and cave-drip waters have been collected each month for an entire year. This water will be analyzed for its stable isotopic composition (O and H). Temperature and relative humidity parameters inside and outside each cave were measured every hour using data loggers. Six precise U/Th ages were obtained using a Neptune multi-collector inductively coupled plasma mass spectrometer. Preliminary results show a continuous, Late Pleistocene to Early Holocene (77 ka to 7 ka) stable isotope record of stalagmite growth. Variations in the δ¹³C composition revealed possible abrupt changes in paleo-vegetation for the area. A slight variation in the δ¹⁸O values did not revealed significant changes.