Mesozoic magmatic-hydrothermal iron oxide deposits (IOCG `clan') in Mexico: A review
Por:
Camprubí A., González-Partida E.
Publicada:
1 mar 2017
Resumen:
Mesozoic magmatic-hydrothermal iron oxide (MHIO) deposits in Mexico have
been identified either (1) in regions close to the paleo-Pacific
convergent margin, in Baja California and southwestern-southern Mexico,
and (2) in regions several hundreds of kilometers inland from that
margin, in Chihuahua and Sonora. The formation of these deposits started
during the transition from dominantly oceanic extensional
tectonomagmatic environments (Aptian-Albian; see Camprubl, 2013) towards
the continental thickening by means of subduction-related magmatic
processes into the Cenozoic. Despite their need for further studies, in
this paper we suggest that MHIO deposits in the type-1 regions, on the
one hand, formed possibly in intra-arc continental settings, similarly
to those that occur in the Coastal Andes Cordillera in South America. On
the other hand, deposits in the type-2 regions are likely to have formed
in back-arc continental settings, which are analogous to those in
eastern Mexico during the Cenozoic (collectively included in the Eastern
Mexico Alkaline Province). MHIO deposits in Mexico are typically
associated with intrusive sequences that include gabbros, diorites and
monzonites within plutonic ensembles that are largely granitic, where
calc-alkaline- and tholeiitic-affinity intrusions display synchronicity
at some degree and complex interactions (magma mixing or mingling). The
oldest MHIO deposits known in Mexico are those in the northern half of
the Baja California Peninsula (Early Cretaceous), in association with
the Peninsular Batholits, and delineating a relatively ephemeral
metallogenic epoch. Contrastingly, MHIO deposits in southwestern and
southern Mexico started forming during the Late Cretaceous and continued
forming during the Cenozoic, in association with the Silicic Large
Igneous Province (SLIP) of the Western and Southern Sierras Madres and
the related back-arc magmatic processes in the Eastern Mexico Alkaline
Province. The age spans for the formation of individual MHIO deposits in
southwestern and southern Mexico appear to be wider than those in the
Baja California Peninsula, a feature that is consistent with the ages of
the associated intrusions but may also explain the fact that MHIO
deposits in southwestern-southern Mexico tend to be larger than those in
Baja California. The case of the late Cretaceous to Eocene (ca. 71 to 48
Ma) multi-stage Pena Colorada deposit in Colima, the largest iron
deposit in Mexico, exemplifies a sort of telescoping process, in which
(1) stages of mineralization that formed proximal to magmatic sources
(skarns and skarnoids) were postdated by (2) distal to source stages
(Kiruna-type stages and hydrothermal veins). It may be speculated that
such evolution may occur in other MHIO deposits elsewhere that were
associated with a steady magmatism or `magmatic supply' unless rapid
exhumation `quenched', and ultimately stopped, this evolution. Such
might be the case of MHIO deposits in the Baja California Peninsula,
where intrusions migrated eastwards between 140 and 80 Ma before being
rapidly exhumed.
The formation of MHIO deposits in regions close to the paleo-Pacific
convergent margin started forming once the accretion of oceanic terranes
was complete by the Early-Late Cretaceous boundary, and such formation
is likely to have been terminated once the continental thickening
reached a critical point during the Laramide orogenic pulse. As such
pulse showed a north-to-south progression, it resulted in the
termination of the formation of `coastal' MHIO deposits earlier in the
Baja California Peninsula than in southwestern and southern Mexico (Late
Cretaceous and Eocene, respectively). (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, Querétaro, Juriquilla 76230, Mexico
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