T136 The Andes from Top to Bottom

Monday, 16 October 2023
1:30 PM - 5:30 PM
326

PRE-ANDEAN TECTONICS AND BASIN EVOLUTION DURING LATE PALEOZOIC GLACIATION IN WEST-CENTRAL ARGENTINA

Paper number: T136-15
Program: Technical Sessions
Time: 4:55 PM – 5:10 PM

Authors

Abstract

The late Paleozoic Paganzo Basin of SW Gondwanaland comprises a disconnected series of clastic outcrop belts distributed across the Precordillera and Sierras Pampeanas regions of Argentina. To address debates over the tectonic conditions and depositional environments during basin evolution, we integrate lithofacies, provenance, stratigraphic, and structural relationships for the Sierra Chica de Zonda with a regional detrital zircon U-Pb geochronological dataset. Carboniferous outcrops within the Sierra Chica de Zonda recorded extensive erosional incision and clastic marine deposition within a glacial paleovalley. Stratigraphic correlations across the Paganzo Basin show similar facies filling other paleovalleys, with a wide range in the thickness of individual stratigraphic packages. These relationships paired with a detrital zircon U-Pb geochronological dataset (generated by LA-ICPMS analyses) of 30 new regional Paleozoic sandstone samples from across the Precordillera and Pampean regions are key to understanding the connectivity of depocenters across the basin and their sediment source regions. Detrital zircon age distributions for isolated Carboniferous outcrop belts reveal contrasting sediment sources throughout the basin, with sediment contributions principally from local sources. In the west, Precordilleran samples display a wide range of U-Pb ages, likely due to local derivation from Precambrian Laurentian basement associated with the Cuyania terrane. In the east, Pampean samples have age distributions that show detrital input from the Ordovician Famatinian magmatic arc and the Neoproterozoic Pampean belt. These signatures suggest deposition in discrete subbasins that may reflect the effects of selective glacial incision and/or intrabasinal deformation along the SW Gondwanan convergent margin.

Geological Society of America Abstracts with Programs. Vol. 55, No. 6

doi: 10.1130/abs/2023AM-391401

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