New age in the geological evolution of the Cerro de Mercado Iron Oxide Apatite deposit, Mexico: Implication in the Durango apatite standard (DAP) age variability
Por:
Corona-Esquivel R., Levresse G., Solé J., Henriquez F., Pi T.
Publicada:
1 dic 2018
Resumen:
Cerro de Mercado Iron Oxide Apatite deposit (CM-IOA) is known as a
classical example of an IOA deposit worldwide and is also probably the
most prolific locality in terms of gem-quality fluorapatite. The CM-IOA
deposit is located in the Chupaderos Caldera Complex (CCC), a large
rhyolitic volcanic center belonging to the Upper Volcanic Supergroup of
Oligocene age. The main Cerro de Mercado IOA mineralization body is
crosscut by a kilometer long rhyodacite dyke that acted as channelway
for the rhyodacite flow. The rhyodacite dyke crosscuts all the volcanic
sequence. K-Ar ages of this dyke range from ca. 28 to 27 Ma. Apatite in
the Cerro de Mercado deposit appears in two different positions, (1)
altered crystals intergrown with martite within massive mineralization,
with or without diopside; and (2) on martite in degassing cavities and
fracture zones, with accompanying chalcedony and calcite.
Crystallization of the apatite phase was complete prior to the eruption
of the overlying felsic flows of the Tinaja Member of the Cacaria
Formation at ca. 31.44 Ma and preserve of potential late thermal event
(McDowell et al., 2005). The mean ages reported by numerous and
different isotopic methods for the fluorapatite DAP are coincident
within the margins of uncertainty with the volcanic host rocks ages. But
DAP ages reported present a significant variability of up to 8%. Such
variability is also found in all dating technics applied in Durango
Apatite (fission-track, U/Pb and (U-Th)/He ages) and suggest a thermal
resetting related to the late volcanic event at 28-27 Ma.
Filiaciones:
Instituto de Geología, Universidad Nacional Autónoma de México, CDMX, Mexico
Centro de Geociencias, Campus, Juriquilla, UNAM, Mexico
Laboratorio Nacional Geoquímica y Mineralogía, Universidad Nacional Autónoma de México, CDMX, Mexico
Departamento de Ingeniería en Minas, Facultad de Ingeniería, Universidad de Santiago de Chile, Chile
Univ Nacl Autonoma Mexico, Inst Geol, Cdmx, Mexico
UNAM, Ctr Geociencias, Juriquilla, Mexico
Univ Nacl Autonoma Mexico, Lab Nacl Geoquim & Mineral, Cdmx, Mexico
Univ Santiago Chile, Fac Ingn, Dept Ingn Minas, Santiago, Chile
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