72-10 Tectonic Inheritance and the Orogenic Architecture of the Andes

Session: Toe to Toe: Cordilleran Systems from Trench to Retroarc Domains (Posters)

Poster Booth No.: 270

Presenting Author:

Brian Horton

Authors:

Horton, Brian K.¹, Capaldi, Tomas N.², Mackaman-Lofland, Chelsea³, Perez, Nicholas D.⁴, Fuentes, Facundo⁵, Constenius, Kurt N.⁶

(1) Institute for Geophysics and Department of Earth & Planetary Sciences, Jackson School of Geosciences, University of Texas at Austin, Austin, TX, USA, (2) Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA, (3) Department of Earth, Environmental, and Planetary Sciences, University of Tennessee, Knoxville, Knoxville, TN, USA, (4) Department of Geology and Geophysics, Texas A&M University, College Station, TX, USA, (5) Independent Consultant, Buenos Aires, Buenos Aires, Argentina, (6) Department of Geosciences, University of Arizona, Tucson, AZ, USA,

Abstract:

Tectonic inheritance plays a key role in the orogenic architecture and structural styles of the Andes mountains and sedimentary basins of western South America. Retroarc structures within the orogenic belt and foreland basin are summarized by considering regional contractional fault geometries, their kinematic interactions with other structures, and the comparative involvement of crystalline basement and sedimentary cover rocks. Overall structural style is strongly influenced by precursor conditions. The concept of tectonic inheritance identifies four factors that influence Andean deformation. (1) Structural inheritance involves the reactivation of preexisting faults or basement fabrics and accompanying basin inversion. (2) Stratigraphic inheritance is exemplified by the preferential localization of interconnected thin-skinned structures above regional décollements developed in wedge-shaped stratigraphic packages versus isolated basement-involved thick-skinned faults formed in provinces with limited cover strata. (3) Rheological properties guide the activation of new structures by means of the integrated strength, composition, fluid content and pressure, and associated mechanical heterogeneities and anisotropies that define crustal and lithospheric architecture. (4) Thermal parameters in the form of initial conditions and later perturbations (such as cooling/heating episodes related to arc magmatism, subducting slab dynamics, or lithospheric removal) can promote inboard advance or outboard retreat of deformation. Spatial and temporal variations in the relative importance of these four inherited attributes resulted in a complex evolution of structural styles during Andean shortening. The major styles, which varied in time and space, include: (1) thin-skinned fold-thrust systems above regional décollements; (2) thick-skinned basement uplifts delineated by isolated high-angle reverse faults; (3) hybrid thrust systems involving interconnected thick- and thin-skinned faults; (4) pre-Andean (preorogenic) and (5) Andean (synorogenic) extensional basins inverted by fault reactivation; (6) upper-crustal backthrust belts; and (7) salt-involved contractional structures. Evaluation of the four modes of tectonic inheritance helps explain why many Andean structures do not bear simple relationships to the Mesozoic-Cenozoic history of plate convergence, subduction, and magmatism along the western margin of South America.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-10014

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