The Messinian stromatolites of the Sierra del Colmenar (Western Mediterranean): facies characterization and sedimentological interpretation

The Messinian stromatolites belonging to the Terminal Carbonate Complex unit, from the northern sector of the Bajo Segura Basin (CAM section, Sierra del Colmenar, SE Spain) have been studied. To understand the direct relationship between the morphologies of the stromatolites and their deposition context in order to reconstruct the environmental conditions for their growth, a detailed study of their architecture, external morphology and internal morphology was carried out (macrofabric and microfabric). The stromatolites are made up of domic bodies laterally linked to each other, generating a macrostructure (bioherms) with lateral continuity. This stromatolitic macrostructure presents variations in its internal morphology, giving rise to seven subfacies product of the environmental changes experienced during the growth of the microbial bushes. The stromatolites are arranged parallel of coastline acting as paleogeographic barriers to reduce the physical stress of the environment. Although in general lines suggests a coastal environment, restricted and shallow for the formation of the whole level, the variation in internal morphology is evidence of minor changes in the physical environment.