Palaeoecological significance of Lithophaga borings in Albian stromatolites, SE Nigeria

Irregular stromatolitic structures within the Mfamosing Limestone in the Calabar Flank, SE Nigeria contain up to five generations of Middle to Late Albian bivalve Lithophaga borings at close spacings. The stromatolitic bodies occurring at more than one horizon are observable at the quarry type locality and other exposures fringing the Precambrian Oban massif. Shells of the boring bivalve often were preserved in their living position. Evidence of intervening erosion between the bored stromatolitic beds at any horizon is lacking. Integration of data from the Lithophaga borings with that of the stromatolites suggests that the latter formed subtidally and underwent synsedimentary lithification in a shallow (< 10 m), low-energy marine setting.