Permian igneous clasts from the Matzitzi Formation, southern Mexico: isotopic constraints on the final amalgamation of Pangaea
Por:
Juarez-Zuniga, Sandra, Solari, Luigi A., Ortega-Obregon, Carlos
Publicada:
1 ene 2021
Resumen:
The tectonic reconstructions of southern Mexico during Late
Paleozoic-Middle Triassic time are related to the final stages of
Pangaea assembly. Petrographic analysis combined with U-Pb and Hf
isotopic analyses of zircon grains belonging to volcanic conglomerate
clasts from the Matzitzi Formation in southern Mexico allow
characterization of the magmatism at the end of Pangaea accretion.
Volcanic pebbles from the Matzitzi Formation have felsic to intermediate
compositions and ages ranging from 269 to 285 Ma, which indicate the
erosion of a Permian volcanic source. The epsilon Hf zircon values show
two groups with different isotopic signatures. Intermediate hypabyssal
samples have epsilon Hf-(t) values ranging from -7.8 to +0.2 and
two-step model ages from 1.6 to 1.7 Ga, suggesting late Paleoproterozoic
to Mesoproterozoic crustal residence times. Felsic volcanic samples have
epsilon Hf-(t) values ranging from -3.5 to +8.8 and crustal model ages
ranging from 0.7 to 1.5 Ga, suggesting Neo-Mesoproterozoic crustal
sources and a juvenile depleted mantle source. Grenvillian grains in
volcanic clasts, as well as their isotopic signatures, suggest that the
volcanic rocks were emplaced over Mesoproterozoic Oaxaquia-type crust
and are related to the Permian-Carboniferous plutonic arc in southern
Mexico, which formed along the northwestern Gondwana margin.
Filiaciones:
Juarez-Zuniga, Sandra:
Univ Nacl Autonoma Mexico, Ctr Geociencias, Campus Juriquilla, Queretaro 76001, Qro, Mexico
Solari, Luigi A.:
Univ Nacl Autonoma Mexico, Ctr Geociencias, Campus Juriquilla, Queretaro 76001, Qro, Mexico
Ortega-Obregon, Carlos:
Univ Nacl Autonoma Mexico, Ctr Geociencias, Campus Juriquilla, Queretaro 76001, Qro, Mexico
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