Geochemistry of periplatform carbonate sediments, Leg 115, Site 716 Maldives Archipelago, (Indian Ocean)

Abstract

Site 716 is a continuous sequence (upper Miocene to Holocene) of periplatform oozes and chalks from the Maldives Ridge, Indian Ocean. Mineralogical and geochemical studies of these carbonate sediments indicate that submarine burial diagenesis has played an important role in the induration of sediments at this site. Metastable carbonates, high-magnesium calcite (HMC) and aragonite, convert to low-maganesium calcite (LMC) rapidly, within 1.1 and 6.0 Ma, respectively. Positive shifts in oxygen isotopic composition record episodes of cementation during burial diagenesis. Intervals with increased accumulation rates of metastable components have undergone more rapid diagenesis than intervals with predominantly pelagic deposition. -from Authors