Plant wax biomarkers informing mid-late Holocene hydroclimate variability from an inland sinkhole in the Northern Caribbean
Abstract
Geological and archaeological records indicate extreme droughts in the Caribbean, resulting in socioeconomic collapse (e.g. Mayans in the Yucatan and smaller populations in the Dominican Republic). Severe droughts have not been documented within the instrumental record for the Caribbean and available paleoclimate records in the northern Caribbean are few. We are therefore reconstructing regional hydroclimate variability from sediment cores taken from three coastal sinkhole basins in the northern Bahamas in order to understand the regional drivers of precipitation. Sinkholes and blueholes are ubiquitous across the carbonate landscapes of the Caribbean, and organic rich sediments accumulated within these basins record environmental variability through time. Plant wax biomarkers preserved within sedimentary organic matter carry a record of past precipitation isotopes. We have learned that terrestrial plant wax markers (n-alkanoic acids) preserved within these coastal sinkhole systems can indeed record regional hydroclimate variability through a 3000-year-old record (Blackwood sinkhole). Yet, when sedimentary inputs are dominated by coastal mangroves, the vegetation in these saline systems are known to impart a different fractionation which complicates interpretations of precipitation. Preliminary plant wax isotope data (measured at a centennial-scale resolution) from an inland sinkhole not currently surrounded by mangroves (Emerald Pond) reveals shifts in the isotopic composition of plant wax compounds (dDC28acid ranges from -178‰ to -93‰). Additional plant wax measurements, combined with other proxies, will be used to infer changing climate dynamics and, in particular, past regional rainfall patterns in the Caribbean, the results of which will be presented at this meeting.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.B51C..07T
- Keywords:
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- 0424 Biosignatures and proxies;
- BIOGEOSCIENCES;
- 0473 Paleoclimatology and paleoceanography;
- BIOGEOSCIENCES;
- 4912 Biogeochemical cycles;
- processes;
- and modeling;
- PALEOCEANOGRAPHY;
- 4924 Geochemical tracers;
- PALEOCEANOGRAPHY