The base metal deposit at Molango, Hidalgo, Mexico: structure and mineralogy

Abstract

The base metal mineralization in Molango (Eastern Mexico) is made up of two types of mineralization that lie in the Huayacocotla Formation dating from the Lower Jurassic: In Molango, the first mineralization is of the stratiform type with Pb - Zn, lies in shale and black boards; meanwhile, the second mineralization is predominant, and is of the filonian type with stockwork-type conduction channels in sandstones and high silicification with Cu, consistent with the underlying sandstones.
In the phyllonian mineralization, through XRD, it was possible to identify pyrite, chalcopyrite, pyrrhotite, small amounts of sphalerite and Co-Ni arsenides. In addition, small amounts of selenides and tellurides of Bi, Ag and Pb were found at the detection limit of the equipment. Meanwhile, the stratiform mineralization is more restricted, and there is a zonal structure, in which it is possible to observe with a hand lens a predominance of pyrite at the base and opaque minerals possibly of galena and sphalerite towards the top. On the other hand, it is worth mentioning that in the study area, the Proto-Jurassic rocks are deformed by thrusts, perhaps due to a period of reactivation of normal faults. Likewise, based on the extensional geodynamic context in which the observed sedimentary series and the mineralization studied here were formed, it is inferred that the association of stratiform facies assembled with sedimentary sequences rich in black shales with exhalative roots, allows us to propose a SEDEX model here. (Exhalative Sedimentary) for these mineralizations.