High-resolution temporal record of holocene ground-water chemistry: Tracing links between climate and hydrology

Jay L. Banner, Mary Lynn Musgrove, Yemane Asmerom, R. Lawrence Edwards, John A. Hoff

Research output: Contribution to journalArticlepeer-review

77 Scopus citations

Abstract

Strontium isotope analysis of precisely dated calcite growth layers in Holocene speleothems from Barbados, West Indies, reveals high-resolution temporal variations in ground-water composition and may provide a new approach to documenting the links between climate variability and fluctuations in the hydrologic cycle such as recharge rates and flow paths. The speleothems grew in a cave that developed in a fresh-water aquifer in uplifted Pleistocene reef limestones. Three periods of ground-water Sr isotope evolution are observed: 87Sr/86Sr values decreased from 6 to 4 ka, increased from 4 to 1 ka, and decreased again after 1 ka. The Sr isotope oscillations appear to record periodic variations in the relative Sr fluxes to ground water from exchangeable soil sites vs. carbonate mineral reactions, as reflected in 87Sr/86Sr values of modern Barbados ground waters. A hydrologic model that explains changes in ground-water flow routes in karst aquifers as a function of amount of rainfall recharge can account for the speleothem Sr isotope record. Independent Holocene climate records that indicate a major period of aridity at around 1.3-1.1 ka in the American tropics correspond with periodic variations in rainfall on Barbados that are predicted by this hydrologic model.

Original languageEnglish (US)
Pages (from-to)1049-1053
Number of pages5
JournalGeology
Volume24
Issue number11
DOIs
StatePublished - Nov 1996

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