Geochemical analysis of Tequesta calcretes

Abstract

Members of the Tequesta, a pre/proto-historic indigenous group of South Florida, cut thousands of postholes into the shallow limestone bedrock of the Metropolitan Square site, located in present-day Miami. Calcrete (limestone soil crust) formations found in and around these postholes serve as a geochemical repository attesting to various human and natural processes at the site. We present here the results of petrographic, total organic carbon (TOC), X-ray diffraction (XRD), X-ray fluorescence (XRF), and stable-isotope analysis, which were used in an attempt to relatively date posthole excavation and to identify patterns of changing site use. Ultimately, the combination of these methods yielded useful insights into paleoenvironment and proposed changes in site use, while failing to provide desired information on chronology. A combined geochemical approach such as that employed here would seem to hold potential for future study of sites located in calcareous/karstic contexts.