Facies characterization and sedimentological scenario of the Messinian stromatolites from Western Mediterranean (Northern Bajo Segura Basin)

CÓNSOLE-GONELLA, CARLOS; VILLAFAÑE PATRICIO GUILLERMO; CORBÍ, HUGO; RUIZ-SÁNCHEZ, FRANCISCO JAVIER

Paris

Congreso; 5th International Paleontological Congress; 2018

International Paleontological Association

The Messinian stromatolites intimately related to the Messinian Salinity Crisis (TerminalCarbonate 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 relationshipbetween the morphologies of the stromatolites and their depositional context in order toreconstruct the paleoenvironmental conditions for their growth, a detailed study of theirarchitecture, external morphology, and internal morphology (macrofabric/general internalstructure and microfabric) was carried out. The studied sequence presents a highly de-veloped stromatolitic level whose macrostructure consists of domical and interdome formsarranged parallel to the coast and acting as a palaeogeographic barrier. The analysis offacies relationships enable us to infer that the stromatolites were formed in a restricted,subtidal-intertidal to supratidal environment. The variation in internal morphology oververtical stromatolite growth provides evidence of minor changes in the physical environmentduring the development of each stromatolitic subfacies. The upper part of subfacies 1 marksthe beginning of a subtidal environment with conditions of constant humidity and low hydro-dynamic energy, which is maintained throughout the development of subfacies 2. Subfacies3 represents a sudden loss of depth and an increase in hydrodynamic wave energy, and thetransition to subfacies 4 indicates the begins of a progressive increase of depth begins thatcontinues until reaching its maximum in subfacies 5. The transition from subfacies 5 to 6indicates a gradual decrease in depth and during the formation of subfacies 7, shallowingcontinued and puts an end to stromatolite growth. Finally, domes and interdome llingmaterial undergo sub-aerial exposure and are shaped by an erosive process, as representedby the late-Messinian unconformity.