New geological and geochronological data of the Placer de Guadalupe uplift, Mexico: a new piece of the Late Triassic-Jurassic Nazas Arc?
Por:
Villarreal-Fuentes, J, Levresse, G, Nieto-Samaniego, AF, Corona-Esquivel, R
Publicada:
10 dic 2014
Categoría:
Geology
Resumen:
Basement exposed in the Placer de Guadalupe-Plomosas uplift in northern
Mexico provides important clues for the geologic evolution of the
region. The stratigraphic units form stacked thrust sheets of psammitic
and calcareous formations, interlayered with magmatic rock. The eastern
calcareous and quartzite formations exhibit structures associated with
ductile deformation, whereas the upper stratigraphic units only contain
structures formed via younger brittle deformation. Porphyry interlayered
in the upper Plomosas Formation has a U-Pb zircon age of 171 +/- 1Ma.
This age is consistent with its stratigraphic position, interbedded
quartzarenites with a maximum depositional age of ~168Ma. Granite
flakes within the Horquilla Formation are dated at 209 +/- 3Ma, and the
La Vinata quartzite exhibits a maximum age of ~193Ma. The Upper
Plomosas Formation correlates well with the arc-related Middle Jurassic
Nazas Formation of northeastern Mexico, constituting the first report of
a Jurassic continental margin arc outcrop in the `Central Mexican Gap
zone'. We document Late Norian to Bajocian ages for the stratigraphic
units cropping out in the Placer de Guadalupe area. The Jurassic age
cluster indicates that the Nazas Arc magmatism in the region occurred
during the Late Triassic and ended in the Middle Jurassic times. Permian
ages previously assigned to these rocks and the occurrence of a
Permo-Triassic deformation event have to be dismissed.
Filiaciones:
Villarreal-Fuentes, J:
Univ Nacl Autonoma Mexico, Ctr Geociencias, Queretaro, Mexico
Levresse, G:
Univ Nacl Autonoma Mexico, Ctr Geociencias, Queretaro, Mexico
Nieto-Samaniego, AF:
Univ Nacl Autonoma Mexico, Ctr Geociencias, Queretaro, Mexico
Corona-Esquivel, R:
Univ Nacl Autonoma Mexico, Inst Geol, Mexico City 04510, DF, Mexico
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