37 Cordilleran Margin Evolution and Supercontinent Tectonics: From Pangea Assembly to North American Orogenesis (Posters)

This session integrates tectonics, petrology, geochronology, stratigraphy, and paleontology to illuminate how Paleo-Pacific plates drove subduction dynamics, crustal evolution, and paleogeographic reconstructions across the complex geological architecture of the American Cordilleras.

Friday, 24 April 2026
8:00 AM - 5:30 PM
LMH, 5th Floor Chapel

U-Pb ZIRCON GEOCHRONOLGY AND Lu-Hf ISOTOPIC CONSTRAINTS ON LATE PALEOZOIC PLUTONS FROM THE ALTOTONGA AREA, VERACRUZ, MEXICO.

Paper number: 37-10
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

Abstract

The Altotonga area in Veracruz state, represents one of the few exposures of the Paleozoic crystalline basement rocks in westernmost Gulf of Mexico region and is crucial because is inferred to be located near the boundary between the Maya Yucatan Block and the Sierra Madre (Guachuchil) terranes. The studied rocks comprise a metasedimentary low-grade sequence intruded by dioritic to granodioritic plutonic suite. Previous K-Ar and Ar-Ar ages have been reported in igneous rocks approximately in 252 Ma and 268 Ma. New U-Pb single zircon data from five samples constrain the metasedimentary protoliths in a maximum age deposition around ~493.6 Ma; subsequently, Late Paleozoic magmatism yields crystallization ages of ~264-276 Ma for diorite, ~278-280 Ma for granodiorite, and ~277-287 Ma for granite. In addition, a granitic drill core records early Triassic ages of ~247-255 Ma. Whereas Lu-Hf zircon isotopic analyses yields ɛHf values between -12.2 and -2.9; Hf176/Hf177 ratios from 0.282416 to 0.282585; such data corresponding to Hf model ages ranging from 969 to 1741 Ma, indicating involvement of ancient continental crust. Integration of U-Pb and Lu-Hf results indicate that basement of the Tampico-Misantla and Veracruz basins exhibits close affinity with the Maya Terrane. Permian tectonothermal events between (~281 and 258) Ma and Early Triassic activity near (~251 Ma) correlate with events documented in the Chiapas Massif. The new data indicates Mesoproterozoic to Neoproterozoic crustal inheritance-recycling during magma generation and supports development of a Permo-Triassic magmatic arc once Pangea was assembled.

Geological Society of America Abstracts with Programs. Vol. 58, No. 3

doi: 10.1130/abs/2026CD-410840

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