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Anthropogenic Thermal Alteration of Marine Bivalves, Recrystallization, and Isotope Integrity

Author(s): Susan Larsen

Year: 2015

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Summary

Archaeologists have given little direct attention to the taphonomic effects of cooking methods for marine invertebrates, particularly the effect on shell mineralogy. Various methods of heating and steaming shellfish directly in the shell are recorded as traditional for Northwest Coast peoples and the shell samples at the Tse-Whit-Zen Village site in Port Angeles, Washington State, contain many specimens that visually appear to be thermally altered. This type of heat exposure has been shown experimentally to cause aragonitic fish otoliths to convert to calcite and become depleted in 18O and 13C, and thus become unsuitable as a source of isotope ratios for paleoenvironmental reconstruction. Biogenic aragonite in marine molluscs is known to alter in the same way, but at lower than expected temperatures. I conducted controlled heating experiments of modern specimens of four taxa of molluscs common in the site assemblage (Clinocardium, Saxidomus, Leukoma, and Ostrea) to determine the conditions (temperature, time) at which isotopic integrity was lost.

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Anthropogenic Thermal Alteration of Marine Bivalves, Recrystallization, and Isotope Integrity. Susan Larsen. Presented at The 80th Annual Meeting of the Society for American Archaeology, San Francisco, California. 2015 ( tDAR id: 395344)


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Spatial Coverage

min long: -169.717; min lat: 42.553 ; max long: -122.607; max lat: 71.301 ;

Arizona State University The Andrew W. Mellon Foundation National Science Foundation National Endowment for the Humanities Society for American Archaeology Archaeological Institute of America