5 The southern margin of the North American cordillera through time

This session deals with the geologic evolution of the southeastern Cordillera of the North American Plate, its role during ancient orogenic cycles, opening of the Gulf of Mexico, and its interaction with the Caribbean Plate.

Wednesday, 22 April 2026
8:00 AM - 12:00 PM
LMH, Meeting Room

Lithospheric boundaries of southernmost Mexico and the connection between the Mexican fold-thrust belt and the Chiapas orogen.

Paper number: 5-4
Program: Technical Sessions
Time: 9:10 AM – 9:30 AM

Authors

Abstract

The geology of Chiapas and Oaxaca is crucial to understanding the tectonic evolution of the southern margin of the North American plate. This region preserves a geological record spanning from the Proterozoic to the present, with a wide variety of lithological units and deformation structures, including faults, shear zones and fold belts. One characteristic feature is the frequency of lithospheric faults, which have been reactivated over time, influencing the formation of tectonic elements and geological processes since the amalgamation of Rodinia and Pangea, to the opening of the Gulf of Mexico, Paleogene shortening, Neogene sinistral faulting and active faulting and volcanism. This study presents an overview of the most important tectonic features of Chiapas and Oaxaca, combining geophysical data (crustal models from magnetotelluric soundings) with surface geological observations, geochronological and petrological studies. The results reveal the continuity of structures at depth and allow the definition of the boundaries between lithospheric blocks, shedding light on the role they play in the structural discontinuity of the Mexican fold-thrust belt front to the south, despite the fact that Paleogene structures develop in the Chiapas fold belt in Mexico and Guatemala, further south.

We present an updated geological map of the state of Chiapas, which shows the distribution of the main lithostratigraphic and structural elements of the region, as well as geological sections through lithospheric structures of the area, and an updated review of the stratigraphy of this important region of Mexico. In particular we review the influence of these regional faults in the apparent disconnection between the Mexican and the Chiapas fold thrust belts, in the distribution of active faults of Chiapas, and in the development of the triple junction between the North American, Cocos and Caribbean plates.

 

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

doi: 10.1130/abs/2026CD-410985

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