Mesozoic volcanogenic massive sulfide (VMS) deposits in Mexico
Por:
Camprubí A., González-Partida E., Torró L., Alfonso P., Canet C., Miranda-Gasca M.A., Martini M., González-Sánchez F.
Publicada:
1 mar 2017
Resumen:
Volcanogenic massive sulfide (VMS) deposits are the most conspicuous
type of deposits that formed during the Mesozoic in Mexico. Many Mexican
VMS deposits display ``classical'' Kuroko-type mineral zonation and
structure, and some of them, as Cuale and La Minita formed in shallow
submarine environments. The most prospective time window for the
formation of VMS deposits in Mexico comprises the Late Jurassic and the
Early Cretaceous. VMS stopped forming during the progressive
continentalization of Mexico, since its metallotectonic processes
(dominated by extensive tectonics) changed giving way to compression
during the late Early Cretaceous; new VMS deposits did not form until
after the opening of the Gulf of California.
Mesozoic VMS deposits in Mexico occur in submarine volcano-sedimentary
sequences that deposited essentially in association with back-arc basins
(now found roughly along the boundaries between tectonostratigraphic
terranes) or within juvenile and slightly evolved arcs (at the internal
parts of the terranes), while few others occur on the epicontinental
seafloor and hinterlands of eastern Mexico. VMS deposits are especially
abundant in the Guerrero composite terrane, and are also present in the
Alisitos and Parral terranes. However, new evidence referred in this
paper indicate the western continental edge of the cratonic block of
Oaxaquia as a promising, new prospective region for VMS deposits.
Interestingly, no VMS deposits are found in the northern part of the
Guerrero composite terrane despite the occurrence of marine
volcano-sedimentary sequences similar to those in the south; such
absence can be related to differential extensional unroofing, much
larger in the southern part of the Guerrero composite terrane than in
the northern part. Many VMS deposits occur along or close to terrane
boundaries, especially around the Guerrero composite terrane. This
distribution reflects the association between VMS deposits and back-arc
basins, which represented the frontal part of terranes or sub-terranes
that were ultimately accreted to the Oaxaquia cratonic block. As a
consequence, VMS deposits usually display strong deformation and
thrusting, and their mineral and compositional zonation can be found
overturned. Due to such common association between these deposits and
terrane boundaries that reactivated during the Cenozoic, VMS deposits
are especially susceptible to overprinting by later metallogenic
processes, unrelated to VMS-producing environments. This susceptibility
may be held accountable for the complex mineral associations found in
the Francisco I. Madero deposit.
The inclusion fluids in the Cuale, La Minita, El Rubi, Tizapa and Campo
Morado deposits have salinities that range from 2.5 to 20.0 wt.% NaCl
equiv. and temperatures of homogenization from 110 degrees to 420
degrees C, although a particular fluid inclusion assemblage (with
daughter halite and sylvite) from a stockwork at the Tizapa deposit
ranged salinities from 39.7 to 64.7 wt.% NaCl and from 35.9 to 43.5
wt.% KCl, and temperatures of homogenization from 440 degrees to 550
degrees C. The general characteristics listed above may account for
mineralizing fluids from magmatic, marine, and modified marine sources.
The entrainment of cool and oxidizing seawater within upwelling fluids
increased as the paleohydrothermal systems waned. The waning stages are
normally represented by barite-rich mineralizations and, in the case of
the La Minita deposit, this notoriously outlasted by Mn oxide
mineralization that reflects even more oxidizing conditions. A similar
evolution is deduced in Cuale, which is the only known Mesozoic VMS
deposit in Mexico that formed in a shallow-submarine environment
together with La Minita. The shallower the formation of VMS deposits is,
the more quickly mineralizing fluids evolve into highly oxidized
end-members, once the paleohydrothermal systems cooled down. The
extremely high-salinity and hot inclusion fluids in Tizapa, despite the
unavailability of further geochemical data, are likely to represent
magmatic brines that did not undergo significant mixing with seawater.
As for the temporal evolution of the studied deposits, they generally
exhibit (1) an increasing magmatic contribution from early to middle
stages for both fluids (as mineralizing fluids grew hotter and more
saline) and sulfur, and (2) the waning of hydrothermal activity towards
the last stages on mineralization, which is characterized by the
prevalence of seawater (as fluids grew cooler, and more diluted and
oxidizing), thus reflecting quite a typical evolution for most VMS
deposits elsewhere. New delta S-34 values for the same VMS deposits
reflect multiple sources of sulfur in the mineralizing fluids: magmatic,
sedimentary/metasedimentary, and marine. Different degrees of dominance
of either source for sulfur in these deposits and in their stages of
mineralization have been inferred, in a way that also responds to a
schematic evolution from magmatic- to seawater-dominated
paleohydrothermal systems. (C) 2015 Elsevier B.V. All rights reserved.
Filiaciones:
Camprubí A.:
Univ Nacl Autonoma Mexico, Inst Geol, Ciudad Univ, Mexico City 04510, DF, Mexico
Instituto de Geología, Universidad Nacional Autónoma de México, Ciudad Universitaria, México, D.F. 04510, Mexico
González-Partida E.:
Univ Nacl Autonoma Mexico, Ctr Geociencias, Blvd Juriquilla 3001, Juriquilla 76230, Queretaro, Mexico
Centro de Geociencias, Universidad Nacional Autónoma de México, Boulevard Juriquilla 3001, Juriquilla, Querétaro 76230, Mexico
Torró L.:
Univ Barcelona, Fac Geol, Dept Cristallog Mineral & Diposits Minerals, Marti & Franques S-N, Barcelona 08028, Catalonia, Spain
Departament de Cristal·lografia, Mineralogia i Dipòsits Minerals, Facultat de Geologia, Universitat de Barcelona (UB), Martí i Franquès s/n, Barcelona, Catalonia 08028, Spain
Alfonso P.:
Univ Politecn Cataluna, Dept Engn Minera & Recursos Nat, Av Bases Manresa 61-73, Manresa 08242, Catalonia, Spain
Departament d Enginyeria Minera i Recursos Naturals, Universitat Politècnica de Catalunya, Av. de les Bases de Manresa 61-73, Manresa, Catalonia 08242, Spain
Canet C.:
Univ Nacl Autonoma Mexico, Inst Geofis, Ciudad Univ, Mexico City 04510, DF, Mexico
Instituto de Geofísica, Universidad Nacional Autónoma de México, Ciudad Universitaria, México, D.F. 04510, Mexico
Miranda-Gasca M.A.:
Minas GRC SA CV Cloncurry Met Ltd, Andador 101 L17 M306, Cuernavaca 62398, Morelos, Mexico
Minas GRC S.A. de C.V.—Cloncurry Metals Ltd., Andador 101 L17 M306, Col. Ce. Chapultepec, Cuernavaca, Morelos 62398, Mexico
Martini M.:
Univ Nacl Autonoma Mexico, Inst Geol, Ciudad Univ, Mexico City 04510, DF, Mexico
Instituto de Geología, Universidad Nacional Autónoma de México, Ciudad Universitaria, México, D.F. 04510, Mexico
González-Sánchez F.:
Inst Tecnol Super Tacambaro, Av Tecnol 201, Tacambaro 61650, Michoacan, Mexico
Instituto Tecnológico Superior de Tacámbaro. Av. Tecnológico 201, Zona El Gigante, Tacámbaro, Michoacán 61650, Mexico
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