Resumo

TRITLLA, Jordi et al. Depósitos de Pb-Zn-Cu-Ba-F-Sr epigenéticos estratoligados en series sedimentarias en relación con salmueras de cuenca: depósitos de tipo “Mississippi Valley” (MVT) y similares en México. Bol. Soc. Geol. Mex [online]. 2006, vol.58, n.1, pp.103-139. ISSN 1405-3322.  https://doi.org/10.18268/bsgm2006v58n1a4.

The low temperature, epigenetic and stratabound Pb-Zn-Cu-Ba-F-Sr-bearing ore deposits enclosed within sedimentary series have been one of the major sources of metals in history. Presently, exploration companies still find these deposits a profitable target due to its simple mineralogy as well as the large tonnage they can present, always considering the mineral disctricts as a whole.

In north-east Mexico, several non-magmatic, low-temperature Pb-Zn-F-Ba deposits have been sistematically considered to represent magmatic-related typologies (skarns, high-temperature replacement deposits, epithermal deposits, etc.). Recently, these deposits have been re-studied and placed within an scenario of deep fluid circulation of basinal brines through the Mesozoic sedimentary series, being enriched in Ba, F and metals during its transit. These fluids gave rise to a series of stratabound epigenetic ore deposits scattered throughout the whole Mesozoic carbonate platform. These deposits are not related with any magmatic period whatsoever; do not cause an intense alteration to the host rocks; oftenly, they present a close association with organic matter, either liquid hydrocarbons or bitument; they display a very simple mineralogy (barite, celestite, fluorite, sphalerite, galena) and present low formation temperatures (90-105 °C) coupled with variable salinities. All these characteristics make these deposits similar to the Mississippi Valley-Type Deposits, Alpine-Apalachian subtype.

In this paper firstly we pretend to perform a revision on the global knowledge of the MVT tipology and, subsequentely, to discuss the presence of this type of deposits within the Mesozoic sedimentary series in Mexico.

Palavras-chave : MVT deposits; general characteristics; geochemistry; deposits in Mexico; state of the art.