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140-2 Late Paleozoic Basin Evolution in West-Central Argentina: Response to Glaciation, Magmatism, and Pre-Andean Orogenesis

Session: Building the South American Cordillera, Paleozoic to Recent: Insights from Geo-Thermochronology

Presenting Author:

Brian Horton

Authors:

Horton, Brian K.¹, Capaldi, Tomas N.², Regier, Nicholas A.³, Starck, Daniel⁴, Fuentes, Facundo⁵

(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) Institute for Geophysics and Department of Earth & Planetary Sciences, Jackson School of Geosciences, University of Texas at Austin, Austin, TX, USA, (4) Independent Consultant, La Plata, La Plata, Argentina, (5) Independent Consultant, Buenos Aires, Buenos Aires, Argentina,

Abstract:

The pre-Andean margin of western South America evolved under diverse tectonic and climatic regimes, including mid to late Paleozoic glaciation, consolidation of Gondwana, and brief assembly then breakup of Pangea. In Argentina, considerable disagreement persists over Devonian to Triassic sedimentation and associated tectonic regimes for multiple basin systems, with variably interpreted phases of contraction, extension, strike-slip, and neutral stress conditions. We present an integrated geochronological analysis of detrital provenance and pre-Andean basin evolution with emphasis on the Sierras Pampeanas and Precordillera provinces of west-central Argentina at 30-33°S. Detrital zircon U-Pb geochronological results identify multiple sediment sources, including uplifted inboard basement provinces in the east, outboard magmatic arcs in the west, and large-scale recycling of Paleozoic basin fill. Field-based analyses of unconformities, marine and nonmarine lithofacies, and cross-cutting structural and stratigraphic relationships point to separate deformational phases with and without regional tectonic subsidence. In particular, we propose that many localized exposures of Carboniferous basin fill are not remnants of a larger regional basin, but instead represent the original narrow glacial valleys (commonly fjords) filled during the Late Paleozoic Ice Age. Detrital records record a latest Paleozoic shift from localized intraplate magmatism to subduction-related arc magmatism along an active continental margin, which was accompanied by crustal thickening during the Gondwanide orogeny. Post-orogenic extensional collapse potentially induced a shift from a regionally integrated basin of Late Carboniferous-Early Permian age to isolated, locally sourced extensional basins of Late Permian-Triassic age.

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

doi: 10.1130/abs/2025AM-7845

Late Paleozoic Basin Evolution in West-Central Argentina: Response to Glaciation, Magmatism, and Pre-Andean Orogenesis

Description

Session Format: Oral

Presentation Date: 10/20/2025

Presentation Start Time: 01:50 PM

Presentation Room: HBGCC, 304C

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