14 Lost Oceans, Shifting Continents: Interdisciplinary Records of Paleo-Pacific Plate Histories in the American Cordilleras

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.

Wednesday, 22 April 2026
1:30 PM - 4:00 PM
LMH, Meeting Room

Review of gabbroic and ultramafic rocks in the northern segment of the Colombian Andes: dismembered ophiolites versus subduction complexes

Paper number: 14-4
Program: Technical Sessions
Time: 2:50 PM – 3:10 PM

Authors

Abstract

Fundamental issues for the reconstruction of the tectonic history of accretionary orogens include the identification of ophiolite formation and emplacement and the evaluation of the upper versus lower plate contribution to subduction complexes.The Northern Andes have been considered as a typical accretionary orogen in which oceanic terranes and supra subduction ophiolites were accreted to the continental margin during the Mesozoic. Whereas the existence of high-pressure metamorphic complexes in the southwestern segment of the Central Cordillera of Colombia have allow to recognized several aspects of the Cretaceous subduction history, lower crust and mantle remnants found associated to metamorphic complexes or as isolated fragments have recently shown its potential to a more complicated Triassic to Cretaceous tectonic history.

As part of a hydrogen exploration project in ophiolites supported by Colombian research agencies ANH-Minciencias (project 047-2025), we are currently reviewing the field, petrographic, geochemical and geochronological characteristics of some of these oceanic remnants in the northern segment of the Central Cordillera. Preliminary results have shown that gabbroic and ultramafic units that can vary in length between 10 to 32 Km and width between 3 and 7 Km, are found serpentinized and metamorphosed in the greenschist to amphibolite facies, and interspersed with low or middle grade meta volcano-sedimentary rocks, or as isolated bodies that preserve an unmetamorphosed stratigraphy. This relations and available geological constraints suggest that the tectonic settings for these occurrences can be related to a Triassic to Cretaceous history of back-arc opening and closure, the evolution of the Cretaceous subduction probabbly link to warm conditions, and the Late Cretaceous to Paleocene arc continent collision that extensively re-organized the margin adding upper and lower plate oceanic fragments. The additional understanding the metamorphic record and new geochronological constraints are expected to provide more in-depth evaluation of these tectonic scenarios.

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

doi: 10.1130/abs/2026CD-411045

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