Determination of the temperature of precipitation of aragonite in shells of Anadara brasiliana (Lamarck, 1819) from Playa Norte, Cazones de Herrera (Holocene, Veracruz, Mexico) by means of trace element analysis

摘要

In this work, data on the precipitation temperatures of aragonite were evaluated from the analysis of three shells of the bivalve species Anadara brasiliana (Lamarck, 1819). The material was collected in the locality known as Playa Norte, belonging to the municipality of Cazones de Herrera, Veracruz, Mexico.The LA-ICP-MS method was applied to determine the concentrations of the elements Mg, Sr and Li in the calcareous matrix of the shells, in order to assess their distribution along them, and to obtain values of the temperature of precipitation of aragonite, taking into account the arrangement of the clear and dark bands of the shell. Concurrently, 25 oxygen stable isotope values were determined for the shells via mass spectrometry to obtain quantitative data regarding the same variable. Finally, the values obtained by both methods were compared. Temperature data from Sr/Li ratios vary between 22.48 degrees C and 25.39 degrees C, while delta O-18 temperatures range from 26.2 degrees C and 33.1 degrees C. Sr/Li temperatures are in strong agreement with data from the Coastal Ocean Observation Lab (COOL), while delta O-18 are not. Possible causes for this include the influence of salinity and evaporation rates on delta O-18 values for the Gulf of Mexico. We conclude that the analysis of the Sr/Li ratio via LA-ICP-MS can be applied reliably to obtain data of precipitation temperatures in this bivalve species, and subsequently in other bivalve species from the Gulf of Mexico. delta O-18 is not a reliable proxy for interpreting temperature values in bivalves from this basin. In addition, we come to the conclusion that Sr/Li ratios can be effectively used as delta O-18-independent temperature proxies for biogenic aragonite.