Researchers commonly have assumed that petrographically and mineralogically pristine aragonitic fossils represent original chemical compositions which, therefore, can be used to obtain paleoenvironmental information. However, a recent study indicates that substantial chemical changes have occurred in pristine- appearing, Holocene-age fossils prior to any aragonite/calcite transformation. Given the occurrence of these chemical changes, information is needed regarding both the chemical diagenetic effects of specific environments and the chronologic progression of such chemical changes. To delineate the chemical effects of a common diagenetic environment, to provide a detailed chronologic framework for early diagenetic changes, and to characterize the diagenetic integrity of various chemical species in aragonite, intraspecies comparisons will be make of the stable isotopic and elemental compositions of dated, wholly aragonitic Holocene corals that have been exposed only to the submarine diagenetic environment. Coral samples already have been obtained from submarine cores, taken off the coasts of St. Croix and Puerto Rico, providing a unique opportunity to study a progressive record of the exposure of aragonite to submarine conditions over the past 10,000 years. This detailed information regarding progressive chemical changes in wholly aragonitic fossils will contribute not only to the understanding of early chemical diagenesis, but will provide critical information for improving the reliability of paleoenvironmental interpretations based on the chemical compositions of fossils.
