Western Kentucky University

Poster Title

Interpreting Trace-element and Stable Isotopic Results Recorded in a Holocene Stalagmite from Buckeye Creek Cave, West Virginia

Institution

Western Kentucky University

Abstract

Speleothems collected from Buckeye Creek Cave, Greenbrier County, WV, exhibit growth records for much of the Holocene, as has been determined through Th-230 dating of multiple specimens. Samples from growth bands were microsampled and traceelement ratios and stable isotopic data for stalagmite BCC-2 have been used to infer paleoenvironmental changes that occurred above the cave during the last ~7500 years. Mg/Ca and Sr/Ca ratios co-vary suggesting similar controls on concentration. Ba/Ca ratios vary inversely with Mg/Ca, Sr/Ca ratios and δ13C. Trace elements may be interpreted to reflect growth rate, mineral-solution reaction, and position of samples along a growth layer along with temporal changes in temperature and precipitation. Carbonate mineral morphology has been examined by SEM, and basic elemental ratios have been obtained on mineral phases using the SEM-EDS at WKU. A deviation in trace elements at ~2700 years BP to 1200 years BP may suggest climatic warming. Centuryscale oscillations in δ18O during the pre-4000 year BP period abruptly give way to less oscillatory, slightly more depleted δ18O values suggesting a significant shift in climatic conditions ~4000 year BP. The last 2000 years of the record are characterized by increasing Mg/Ca and δ13C. During the same period Ba/Ca increases and then abruptly decreases, while Sr/Ca decreases and then abruptly increases and stabilizes. These data may reflect land-use practices such as deforestation by the indigenous people inhabiting this area.

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Interpreting Trace-element and Stable Isotopic Results Recorded in a Holocene Stalagmite from Buckeye Creek Cave, West Virginia

Speleothems collected from Buckeye Creek Cave, Greenbrier County, WV, exhibit growth records for much of the Holocene, as has been determined through Th-230 dating of multiple specimens. Samples from growth bands were microsampled and traceelement ratios and stable isotopic data for stalagmite BCC-2 have been used to infer paleoenvironmental changes that occurred above the cave during the last ~7500 years. Mg/Ca and Sr/Ca ratios co-vary suggesting similar controls on concentration. Ba/Ca ratios vary inversely with Mg/Ca, Sr/Ca ratios and δ13C. Trace elements may be interpreted to reflect growth rate, mineral-solution reaction, and position of samples along a growth layer along with temporal changes in temperature and precipitation. Carbonate mineral morphology has been examined by SEM, and basic elemental ratios have been obtained on mineral phases using the SEM-EDS at WKU. A deviation in trace elements at ~2700 years BP to 1200 years BP may suggest climatic warming. Centuryscale oscillations in δ18O during the pre-4000 year BP period abruptly give way to less oscillatory, slightly more depleted δ18O values suggesting a significant shift in climatic conditions ~4000 year BP. The last 2000 years of the record are characterized by increasing Mg/Ca and δ13C. During the same period Ba/Ca increases and then abruptly decreases, while Sr/Ca decreases and then abruptly increases and stabilizes. These data may reflect land-use practices such as deforestation by the indigenous people inhabiting this area.