Life in a Shell. Using Archaeological Shell Assemblages for Palaeoenvironmental Reconstruction: Preliminary Isotope Analysis of Polymesoda (Geloina) coaxans (Gmelin, 1791) from Bentinck Island, Gulf of Carpentaria

21st April 2013

Jane Hinton TA AA76Jane Hinton

BA(Hons), School of Social Science, The University of Queensland, November 2012

Archaeological interpretations in Australia and the Pacific have increasingly emphasised past climate change as a key driver of Holocene cultural change. Many studies, however, have relied on palaeoclimate data sets from locations geographically removed from the archaeological materials under investigation. Local high-resolution proxy climate data correlated with high-resolution archaeological data at similar spatial and temporal scales are essential to build cogent models of past human-environment interactions. Given the scarcity of local proxy palaeoclimate archives for north Australia, this study explores the potential for using archaeological shell assemblages for palaeoenvironmental reconstruction using the estuarine bivalve, Polymesoda (Geloina) coaxans from Bentinck Island, Gulf of Carpentaria.

Throughout their lifetimes, bivalves record information in shell structures about the ambient environment in which they grew. Precipitated into shell carbonates, stable isotope profiles can be used to determine periodicities and amplitudes of past climate conditions. Although many successful shell stable isotope studies have been conducted internationally, few have been attempted in Australia. This research applies high-resolution sampling and high-precision spectrometry methods not previously employed in Australian archaeological contexts. Results demonstrate that high-resolution stable oxygen and carbon isotope profiles of modern and archaeological specimens of P. coaxans track broad seasonal variability of wet and dry seasons owing to variations of rainfall and tidal systems in the estuary. The methods and findings provide the basis for using archaeological shellfish assemblages to build an understanding of past climate variability beyond instrumental records using sclerochemical techniques.

Image caption: In May 2009, Site 46A Mosquito Story, a dense 1 m2 surface scatter of P. coaxans was excavated under the auspices of the Wellesley Region Ancient Cultural History Project (photograph courtesy of Daniel Rosendahl).
Jane Hinton
Life in a Shell. Using Archaeological Shell Assemblages for Palaeoenvironmental Reconstruction: Preliminary Isotope Analysis of Polymesoda (Geloina) coaxans (Gmelin, 1791) from Bentinck Island, Gulf of Carpentaria
June 2013
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Thesis Abstracts
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