The investigator proposes to study diagenetic modifications in transgressive-regressive depositional sequences. This systematic study will include three major components: a) detailed geochemical and petrographic characterization of transgressive-regressive Tertiary sequences of Northern Puerto Rico; b) geochemical modelling of transgressive-regressive diagenetic settings using the empirical data to constrain models; and c) detailed geochemical and petrographic study of a Paleozoic sequence in the central North American midcontinent to test applicability of such models and usefulness of Tertiary analogues for the Paleozoic. Petrographic characterization will include conventional petrographic examination of polished slabs and thin sections under binocular microscopes and polarizing microscopes, examination of polished thin slabs and thin sections using cathodoluminescence and fluorescence microscopy, and examination by scanning electron microscopy. The geochemical characterization of selected componenets will include minor, trace and ultra-trace element determinations, carbon and oxygen stable isotope compositions and 87Sr/86Sr determinations. Modelling will include geochemical modelling of fluid chemistry and mineral stability of the systems to assess the thermodynamic limitations of the system, and diagenesis-sea level oscillation models to evaluate a broad range of scenarios that could be present in the gologic record.
