Foreland Basin Record of Uplift and Exhumation of the Eastern Cordillera, Northwest Argentina

Abstract

The style, tempo, and timing of orogenic plateaus such as the Altiplano‐Puna in South America are actively debated. Foreland basin strata in northwestern Argentina preserve a record of the eastward propagation, uplift, and erosion of the eastern margin of the high topography of the Puna plateau and Eastern Cordillera. Herein, we present new sedimentologic and geochronologic data from the Neogene foreland basin strata and modern fluvial sediments at 23°S to reveal the timing of growth and erosion of the modern plateau margin. Traditional sedimentologic approaches, including conglomeratic clast counts and sandstone point‐counts, combined with detrital zircon U‐Pb age distributions preserve robust signatures that track changes in sediment provenance over the past 12 Ma. Growth of the modern plateau edge commenced between 12 and 7 Ma and erected a topographic barrier that cut off the supply of sediment from more westerly sources. Erosion of this rising block has progressively dissected a cover of early Paleozoic sediments of the Mesón and Santa Victoria Groups, leading to deep incision into the pre‐Cambrian metasediments of the Puncoviscana Formation that continues today. Detrital apatite and zircon fission track data from the both the Neogene strata and modern streams document erosion of the frontal block at a rate of about 0.6 mm/a.

The geologic interpretation of the detrital thermochronology record within a stratigraphic framework, with examples from the European Alps, Taiwan and the Himalayas

“…However, sedimentary successions often record major provenance changes (Clift et al, 2006;Tatzel et al, 2017;Rahl et al, 2018), whereby provenance indicates all characteristics of the source area from which clastic sediments and sedimentary rocks are derived, including relief, weathering and source rocks (Ingersoll, 2014). A reliable provenance assessment may require a multiple-method approach to single-grain analysis (Carter, 2019;Danišík, 2019) and a careful inspection of thermochronologic age trends along the analyzed stratigraphic succession (e.g., Glotzbach et al, 2011).…”

“…Potential provenance changes may be further supported by the analysis of framework minerals and heavy mineral suites in the stratigraphic units already analyzed by detrital thermochronology techniques (e.g., Baldwin et al, 1986;Garver and Brandon, 1994;Lonergan and Johnson, 1998;Ruiz et al, 2004;Tatzel et al, 2017;Rahl et al, 2018).…”

Drainage Reorganization Across the Puna Plateau Margin (NW Argentina): Implications for the Preservation of Orogenic Plateaus

“…Conversely, in unstable segments fluvial external fluvial erosion rates are several times higher than rates on the Puna Plateau. TCN‐based external erosion rates in segments 6 and 8 range between ∼80 and 120 mm/kyr (Bookhagen & Strecker, 2012; Schildgen et al., 2016), while long‐term (∼10 Ma) apatite and zircon fission track‐based external erosion rates in segment 10 are ∼600 mm/kyr and sediment yield‐based estimates are an order of magnitude larger (∼3,000–6,000 mm/kyr; COREBE, 1999; Rahl et al., 2018).…”

Constraining Andean Propagation of Exhumation at the Limit of the Eastern Cordillera, NW Argentina, Using Low‐Temperature Thermochronology in a Structural Context

“…The Mesón Group consists of up to 3,000 m thick marine siliciclastic rocks (Aceñolaza, 2003; Moya, 1998; Sanchéz & Salfity, 1999), although thickness varies locally, and is divided into upper and lower coarse‐grained, cliff‐forming quartzite units, and the middle, finer‐grained Campanario Formation. An unconformity exists between the Mesón Group and the overlying upper Cambrian‐lower Ordovician Santa Victoria Group (Rahl et al., 2018; Vaucher et al., 2020). The Santa Victoria Group consists of alternating quartz‐rich sandstones and shales with a thickness of a few thousands meters (Aceñolaza, 2003; Moya, 2015).…”