Estratigrafía, sedimentología y evolución isotópica del tránsito Podolskiense-Myachkoviense (sector Lois-Ciguera, Cuenca Carbonífera Central, Zona Cantábrica)

Abstract

It has been studied the stratigraphy, sedimentology and isotopical geochemistry of the Podolskian-Myachkovian interval in the Lois-Ciguera sector (Central Coal Basin, Cantabrian Zone), formed by Bachende limestones (late Kashirian-late Podolskian /Myachkovian), Dueñas sandstones, shales and limestones (Myachkovian) and Ciguera limestones (Myachkovian), that had been correlated with Lena Group. The main mineralized level of the Salamón gold deposit is near the boundary between the units of Bachende and Dueñas, and consists in black silicificated and laminated shales, that are sometimes brecciated. There have been realized 72 analyses of stable isotopes (13C and 18O), 68 in micrite and 4 in cements. The Podolskian-Myachkovian boundary could be reflected in the isotopical sign. This succession was deposited in a carbonate ramp, that was occasionally invaded by terrigenous materials which disabled, totally or partially, the production of carbonate, giving place to the development of a siliciclastic-mixed shelf. The main production of carbonate was focused in the mid- and outer-ramp and was controlled by calcareous algae buildups and mud mounds.