EFFECT OF BIOGEOCHEMICAL DIAGENESIS ON SEDIMENT FABRIC IN SHALLOW MARINE CARBONATE SEDIMENTS NEAR THE DRY TORTUGAS, FLORIDA

Shallow marine carbonate sediments near the Dry Tortugas undergo exten sive biogeochemical diagenesis upon deposition, resulting in postdepos itional fabric comprised of micritic aggregates of clay-sized particle s, a matrix of peloidal mud, and intraparticular cementation. Freshly deposited primary skeletons, mostly Halimeda fragments, yield micritic aggregates of clay-sized particles, which then form peloidal mud fabr ic upon compaction. The cryptocrystalline particles produced by micrit ization are later replaced by high magnesian calcite. Cementation is o bserved in the intra-particular microenvironment. However, no inter-pa rticular, grain-binding cement was detected throughout the gravity cor e samples investigated.