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• Silurian deep-marine foreland basin with distinct mass-transport deposits. • Carboniferous paleo-fjord filled by delta, fan delta, and subglacial fan deposits. • Detrital zircon U-Pb provenance data reveal Pampean and local eastern sources. • Paleozoic deformation & glaciation altered sediment dispersal & basin configuration. The Precordillera of western Argentina displays a complex pre-Andean stratigraphic record related to Paleozoic convergence along the SW margin of Gondwana. Sedimentologic and U-Pb detrital zircon geochronological results for the Silurian Rinconada Formation and Carboniferous Jejenes Formation of the eastern Precordillera provide insight into sediment provenance, drainage reorganization, and climatic/tectonic interactions during Paleozoic deformation and glaciation. Measured sections and lithofacies analyses indicate sediment gravity flow and mass-transport deposition in a Silurian submarine fan during shortening in the adjacent Famatinian orogenic belt. This foreland basin was deformed during the Late Devonian Chanic orogeny, prior to glacial incision of remnant topography during the Late Paleozoic Ice Age. Analyses of unconformities, cross-cutting relationships, and lithofacies within a Carboniferous paleovalley (Quebrada Grande, Sierra Chica de Zonda) indicate four facies associations (fjord-head delta, distal fjord, fan delta, and subglacial fan) within a fjord setting governed by glacial advance and retreat. U-Pb results for Carboniferous sandstones (7 samples, 840 analyses) indicate derivation from Western Pampean basement with progressive drainage expansion to include the Famatinian magmatic arc and Eastern Sierras Pampeanas. Evolution from a Silurian marine foreland basin to an isolated Carboniferous fjord reflects major orogenic and climatic transitions in SW Gondwana. Ordovician-Silurian (Famatinian) and Late Devonian (Chanic) shortening generated topography that was subsequently beveled by glacial erosion during the Carboniferous. We suggest that Paleozoic deformation related to subduction and terrane collision helped drive changes in sediment dispersal and basin configuration, while climate changes during regional glaciation regulated erosion/deposition and the spatial extent of sediment accommodation.
Regier et al. (Mon,) studied this question.