The Neuquén group: The reconstruction of a Late Cretaceous foreland basin in the southern Central Andes (35–37°S)

Cretaceous and Eocene Rapid Cooling Phases in the Southern Andes (36°–37°S): Insights From Low‐Temperature Thermochronology, U‐Pb Geochronology, and Inverse Thermal Modeling From Domuyo Area, Argentina

“…The oldest cooling age and the thermal histories of Choiyoi Group samples reflect and Albian-Campanian cooling episode, lasting since ∼110 to 75 Ma (Table 1, Figures 8a, 8b, and 10c, and stage 1B in Figure 9c). This cooling episode is consistent with: (i) the onset of the Andean orogeny interpreted by provenance studies in the foreland of the Southern Andes between 34°S and 39°S Borghi et al, 2019;Di Giulio et al, 2012Gómez et al, 2019;Tunik et al, 2010) (Figures 2 and 3); (ii) the beginning of exhumation and magmatism in the fore-arc (Glodny et al, 2008;Tapia et al, 2020); and (iii) a major change in plate's configuration and spreading rates at a global scale (Matthews et al, 2012;Müller et al, 2016;Somoza & Zaffarana, 2008). Assuming the geothermal gradient of ∼51 °C/km (Sigismondi, 2013;Sigismondi & Ramos, 2009a, 2009b, the Albian-Campanian rapid cooling event implies maximum cooling rates of 12 ± 4 to 23 ± 10 °C/Ma and exhumation rates of up to ∼0.5 ± 0.2 mm/yr (see Table S4.2 for de- The location of samples is projected onto the profile maintaining their relative elevation.…”

“…tails about calculation). This phase of the thermal history represents the earliest tectonically driven cooling event recognized in the ChMFTB, and can be precisely correlated with the maximum depositional ages of ∼109-100 Ma for the first synorogenic deposits in the Neuquén Basin, represented by the Neuquén Group (Borghi et al, 2019;Di Giulio et al, 2012Fennell et al, 2015;Gómez et al, 2019;Tunik et al, 2010, Figures 2 and 4). These deposits register >1,500 m of sedimentary rocks in some sectors of the basin (Legarreta & Uliana, 1999), and between 250 and 550 m in its northern part at 34°-36°S (Borghi et al, 2019;Gómez et al, 2019;Mescua et al, 2013;Orts et al, 2012).…”

“…This phase of the thermal history represents the earliest tectonically driven cooling event recognized in the ChMFTB, and can be precisely correlated with the maximum depositional ages of ∼109-100 Ma for the first synorogenic deposits in the Neuquén Basin, represented by the Neuquén Group (Borghi et al, 2019;Di Giulio et al, 2012Fennell et al, 2015;Gómez et al, 2019;Tunik et al, 2010, Figures 2 and 4). These deposits register >1,500 m of sedimentary rocks in some sectors of the basin (Legarreta & Uliana, 1999), and between 250 and 550 m in its northern part at 34°-36°S (Borghi et al, 2019;Gómez et al, 2019;Mescua et al, 2013;Orts et al, 2012). Moreover, the sedimentary evidence at 36°-37°S indicates >2,500 m of denudation driven by the Late Cretaceous contractional phase of the Southern Central Andes, shaping the mountain system with a topographic front defined by the Cordillera del Viento anticline between 70°00′W and 70°30′W (present coordinates) (Borghi et al, 2019, Figure 2).…”

“…Therefore, erosion would have started almost simultaneously with the onset of uplift of Choiyoi Group units, with generation of positive relief and intense denudation. A humid paleoclimate has been described for Upper Cretaceous deposits at 34°-37°S (Borghi et al, 2019;Lothari et al, 2020), and climate reconstructions based on the study of contemporary foreland deposits in the Patagonian Andes indicate global greenhouse conditions for middle Cretaceous times (Varela et al, 2018, and references therein). This climate pattern supports the massive removal of the easily erodible Mesozoic sedimentary rocks overlying the basement of the Neuquén Basin, resulting in a remarkable acceleration of exhumation rates since ∼110 Ma.…”

Role of the Down-Bending Plate as a Detrital Source in Convergent Systems Revealed by U–Pb Dating of Zircon Grains: Insights from the Southern Andes and Western Italian Alps

“…1.1 Ga (Figure 2C). At around 100 Ma, the region started to become affected by contractional deformation, possibly linked to the global-scale plate reorganization produced by the opening of the Southern Atlantic Ocean [57] (see also [15] for discussion). In the Neuquén Basin, this tectonic inversion triggered a rapid reorganization of the drainage pattern caused by the transition from a back-arc extensional setting to a retro-arc contractional basin.…”