Early diagenetic microbial induced cementation in Late Pleistocene (MIS 5e) shallow-water marine deposits of the Taranto Gulf (South Italy)

A MIS 5e shallow water calcarenite containing a rich fossil macro-fauna and flora, cropping out along the Mar Piccolo (Northern Ionian Sea) coastline, was analysed. Most of the bioclasts are made of fragmented and variously micritised skeletal grains. Very early diagenetic cementation of the original sediment coeval to micritization was inferred, due to a micritic cement forming sub-millimeter wavy envelops and/or columnar bridges binding the grains, often showing clotted peloidal or aphanitic microbial fabrics, associated with micritic filaments consistent with fossil bacterial forms. This implies the occurrence of an epilithic to endolithic intergranular microbial biofilm that mediated syn-sedimentary stabilization and cementation of the incoherent sand-grade sediment.