Mineralogical Study of the Seafloor Diagenesis of Carbonate Sediments Near DryTortugas, Gulf of Mexico, Using Rietveld Method of Crystal Structure Refinement

摘要

The carbonate sediments from Fort Jefferson National Monument area were studiedfor mineralogy using X-ray powder diffraction (XRD) in order to evaluate the effects of seafloor diagenesis on sediment structure. Cementation is suggested at the depths of 120 cm and below by the increase in high-Mg/low-Mg calcite ratio within fine-grained matrix. The relative amounts of calcium carbonate phases were determined by the Rietveld crystal structure refinement. Seafloor diagenesis may be significant at the sediment depths which are not affected by bioturbation and storm mixing.