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

The Early Cretaceous transgression in the Tlaxiaco Basin: Evidence from the Tonalá and San Miguel Papalutla formations, Santo Domingo Tonalá, Oaxaca, Mexico.

Paper number: 37-12
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

Abstract

 

The Tlaxiaco Basin in southern Mexico preserves one of the most complete stratigraphic records of crustal extension (rift) and sea-floor spreading (post-rift) during the breakup of Pangea. While Jurassic units have been extensively studied as key archives of rifting processes and transgressive cycles during the Early and Middle Jurassic, post-rift processes during the Late Jurassic and Early Cretaceous remain poorly understood.

This study provides new insights into Early Cretaceous paleoenvironmental evolution and transgressive processes in the Tlaxiaco Basin. We present a detailed sedimentological analysis of the Tonalá (new name) and San Miguel Papalutla formations in Santo Domingo Tonalá, Oaxaca, Mexico. Our dataset includes facies and microfacies analyses, gamma-ray profiling, U-Pb detrital zircon geochronology, and ammonoid biostratigraphy.

The Tonalá and San Miguel Papalutla formations record a major marine transgression, evolving from tidal coastal environments to deeper basinal facies. We interpret this paleoenvironmental evolution as a response to passive-margin development during the post-rift stage of the breakup of Pangea. Furthermore, the occurrence of the Neocomites neocomiensiformis ammonite assemblage in the San Miguel Papalutla Formation constrains this transgression to the early Valanginian and allows correlation with the global third-order sequence KVa2. Together, these results constrain the relationship between sedimentation and Tethyan marine circulation in the Tlaxiaco Basin.

Overall, this study refines the stratigraphic and paleoenvironmental framework of the Tlaxiaco Basin and improves our understanding of Early Cretaceous transgressive cycles during post-rift evolution associated with the breakup of Pangea in southern Mexico.

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

doi: 10.1130/abs/2026CD-410830

© Copyright 2026 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.