Subaerial explosive deposition of magnetite-apatite mineralization: The Artillero deposit, Pena Colorada district, Colima, Mexico
Por:
Levresse, Gilles, Tornos, Fernando, Velasco, Francisco, Corona-Esquivel, Rodolfo
Publicada:
1 nov 2020
Resumen:
The Artillero magnetite deposit is a satellite orebody within the Pena
Colorada iron district, Mexico. The mineralization consists of a
stratiform orebody formed of subaqueous pyroclastic magnetite
interbedded with welded rhyodacite. This was likely deposited in a
shallow maar crater, capping breccia pipes and feeder dikes, all hosted
by coherent Cretaceous rhyodacite. All of these features suggest that
this mineralization was formed by the crystallization of iron-rich melts
in a subaerial environment. The formation of the magnetite ore in
Artillero and Pena Colorada at 90 +/- 11 Ma and 81 +/- 3 Ma (U-Pb zircon
and apatite), respectively, is coeval with the deposition of the
rhyodacite host rocks (84 +/- 1 Ma; U-Pb zircon). The likely source of
the iron-rich melts was the mantle wedge, having a small but noticeable
crustal contamination due to the input of fluids derived from
dehydrating slab or continental crust incorporated via subduction
erosion, which is reflected in an increase in the Sr-87/Sr-86 values of
the Guerrero volcanic arc. Iron-rich melts ascended through strike-slip
structures related to compression/extension processes caused by the
post-Laramide inversion. The shallow emplacement of the melts favored
the separation of large amounts of low-density aqueous fluids, which
increased wetting properties of the iron rich magma, favored explosive
extrusion, and formed maar-diatreme complexes.
Filiaciones:
Levresse, Gilles:
Univ Autonoma Mexico, Ctr Geociencias, Queretaro, Mexico
Tornos, Fernando:
Inst Geociencias CSIC UCM, Madrid, Spain
Velasco, Francisco:
Univ Basque Country, Dept Mineral Petrol, UPV EHU, Leioa 48940, Spain
Corona-Esquivel, Rodolfo:
Univ Autonoma Mexico, Inst Geol, Cu, Mexico
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