Publication Date

8-2013

Advisor(s) - Committee Chair

Jason Polk (Director), John Andersland, Joshua Durkee, Jennifer Cole

Degree Program

Department of Geography and Geology

Degree Type

Master of Science

Abstract

Barbados is the easternmost island in the Caribbean region, and is uniquely situated between the Atlantic Ocean and Caribbean Sea. Being an isolated island with a karstified aquifer providing the majority of the nation’s water resources, Barbados has found itself in water scarce situations in recent years. In order to better understand natural shifts in groundwater recharge (which is determined by shifts in precipitation), longer records of precipitation are needed than are available from modern measurements. This study presents a paleoclimate reconstruction for the late Holocene on Barbados using stable and radiogenic isotope ratios in speleothem lamina as proxies. In addition, it introduces the use of novel mineralogical analyses using Raman spectroscopy and large chamber-scanning electron microscopy to supplement the oxygen isotope record. For the past 1,500 years, the speleothem record indicates average δ18O values near -4.1 0/00, maximum δ18O values around -3.2 0/00 that coincide with the Little Ice Age climate event, while minimum δ18O values around -5.3 0/00 occur during the Medieval Climate Anomaly. Raman spectral analysis shows a recent period of increased Mg substitution, which potentially represents anthropogenic changes to the island’s epikarst aquifer caused by European settlement and sugar cane cultivation on Barbados. Electron imaging revealed chemically distinct layers of detritus within the stalagmite sample, facilitating precise sampling for U-series dating while also providing some information on the nature of weathering on the island. Additionally, time series analysis of the isotope record indicates multidecadal and multicentennial periodicities that conform well to that of the Atlantic Multidecadal Oscillation exerting influence on rainfall variability at the decadal scale, and the Intertropical Convergance Zone modulating rainfall at the multicentennial scale. Collectively, these data provide a climate reconstruction for the island of Barbados that is useful for better understanding change in cyclic precipitation patterns, as well as non-destructive methods for speleothem analysis that complement the isotopic study, while allowing sample preservation.

Disciplines

Geochemistry | Geology | Hydrology

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