A LATE HOLOCENE PALEOCLIMATE RECONSTRUCTION FROM PUERTO RICO BASED ON A CAVE SPELEOTHEM

We developed a late Holocene record of Caribbean paleoclimate based on a 47 cm long speleothem from Cueva Juan Nieves in Puerto Rico. Four uranium/thorium ages and visual examination suggest uninterrupted deposition from ~5000 to 500 years BP. 468 stable oxygen isotope measurements along the speleothem growth axis yield a decadal resolution record, which we interpret primarily as a proxy for rainfall amount. Combined with a previously published Puerto Rican speleothem record spanning the last 800 years (Winter et al., 2011), the data suggest no long-term trend in precipitation during the mid-to-late Holocene. There is considerable centennial-scale variance, however, which may reflect Atlantic Multidecadal Oscillation-like variability. The most remarkable feature in the record is a long period of drought from 1400 years BP to 1000 years BP, which may correspond with dry conditions seen in speleothem records from Cuba and Mexico. Overall, there is a notable lack of correlation between this record and other regional proxy records from the Caribbean, suggesting either considerable spatial variability in paleorainfall or additional drivers of δ¹⁸O overprinting the precipitation signal.