40 The western equatorial Pangea: Geological, geophysical, geochronological, and paleoecological insights on the youngest supercontinent assembly and breakup on Earth (Part 2)

This session welcomes studies in Mexico, southwestern North America, and northwestern South America investigating the Pangea’s supercontinent cycle from tectonic, stratigraphic, paleoecologic, geophysical, geochronologic, and paleogeographic perspectives to offer insights into its assembly and breakup.

Friday, 24 April 2026
1:30 PM - 5:30 PM
LMH, Isla Carmen

Carboniferous to Triassic magmatism in the Las Delicias Terrane (northeastern Mexico) and its implication for the evolution of western Pangea

Paper number: 40-2
Program: Technical Sessions
Time: 1:55 PM – 2:15 PM

Authors

Abstract

The Las Delicias Terrane (Coahuila, Mexico), comprising the Las Delicias Formation and the crosscutting Acatita Intrusive Suite, records distinct stages of Carboniferous to Triassic magmatism, which potentially reflect a complete orogenic cycle associated with the evolution of western Pangea. This study integrates geological mapping, petrography, whole-rock major and trace element geochemistry, zircon U–Pb geochronology, and zircon Lu–Hf isotopic data from key igneous units.

The Las Delicias Formation includes deformed volcaniclastic deposits, rhyolites, and basalt–andesite rocks with zircon U–Pb ages between ~327 and ~273 Ma. MORB-like geochemical signatures, together with an isotopic shift from negative εHf values (−9) toward more juvenile values (+11), suggest development of a Permian back-arc basin setting. In contrast, the Triassic Acatita intrusive suite (~223–211 Ma) includes intermediate (granodiorites and tonalites) and mafic facies (gabbros and diorites), mafic enclaves (gabbros, diorites, monzodiorites, etc.), and dikes, recording magma mixing from different sources as well as fractional crystallization. The results indicate that the Las Delicias Terrane experienced arc and back-arc volcanism, followed by basin inversion due to crustal thickening, and subsequent plutonism during orogenic collapse. This sequence of events would have resulted from the interactions between Laurentia and Gondwana during the cycle of Pangea.

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

doi: 10.1130/abs/2026CD-410903

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