Environmental influences on the formation of sedimentary fabric in a fine-grained carbonate-shelf environment: Dry Tortugas, Florida Keys

Abstract

 Sedimentological studies were undertaken in the Dry Tortugas to examine environmental influences on the formation of sedimentary fabric. ²³⁴Th, ²¹⁰Pb, grain size, porosity, and fabric analyses reveal the presence of a soft, fine-grained, well mixed surface layer underlain by compact, shelly, intensely bioturbated carbonate muds. Vertical zonation of biogenic structures indicates that deep bioturbation is advective and results in transport of fine material to the seabed surface. The impact of physical oceanographic processes appears to be restricted to the surface layer; however, potential for preservation of this layer in the sediment record is low due to intense mixing in deeper sediments. Thus, preserved sediments retain an incomplete record of the dominant benthic processes at the study area.