ABSTRACT

Trace elements (e.g., Sr, Mg, and U) in coral skeletons are widely used as a potential robust paleothermometers. However, there is little consensus among workers on the chemical pretreatment of skeletal samples, which contain small amounts of organic material and inorganic detritus enriched in many metals compared to the skeleton. We tested the analytical effects of chemical treatment on coral aragonite by comparing several chemical treatments for Mg/Ca and Sr/Ca ratios as well as oxygen and carbon isotopic ratios. Our results suggested that the Sr/Ca ratio and stable isotopic ratios are resistant to chemical treatments. However, organic matter or crystal surfaces in corals could absorb more than 40% of magnesium although 60% of magnesium in coral aragonite substitutes for calcium. Our results suggest that it is expedient to remove impurities by the method outlined here, especially before determining Mg/Ca ratios in corals for paleoenvironmental reconstruction.