El volcanismo jurásico superior de la Formación Río Damas-Tordillo (33°-35,5°S): antecedentes su sobre petrogénesis, cronología, proveniencia e implicancias tectónicas.

Abstract

ABSTRACT. The uppermost Jurassic continental and volcanic deposits of the Río Damas-Tordillo Formation represent an interval of intense continental deposition within the Jurassic to Early Cretaceous dominantly marine environment of the Mendoza-Neuquén back-arc basin. Stratigraphic and geochronological data indicate that progressive emersion of the arc and forearc domain, disconnecting the back-arc region from the Pacific Ocean, occurred during occurred during the Late Jurassic and probably the Early Cretaceous (~160-140 Ma). This change in the margin configuration induced a marine regression and the subsequent deposition of continental material in the back-arc basin. The most likely source of the sediments would have been the Jurassic arc, located west of the back-arc basin. The maximum depositional age of 146.4±4.4 Ma obtained from a red sandstone immediately below volcanic rocks confirms recent Tithonian maximum depositional ages assigned to the Río Damas-Tordillo Formation, and suggests that the volcanic rocks, overlain by marine fossiliferous Tithoninan-Hauterivian sequences, should have erupted within a short time span during the Late Jurassic. Volcanism was probably facilitated by the presence of extensional structures related to the formation of the back-arc basin. Elemental and isotopic data, along with forward AFC models, suggest a depleted sub-arc asthenospheric mantle source for the volcanic rocks and the fractionation of olivine and plagioclase, along with small volumes of lower crust assimilation, as the main processes involved in the magmatic evolution. It is not possible to establish a different source and petrogenetic conditions for the Río Damas-Tordillo Formation and the magmatism in the arc domain located further west, at the present-day Coastal Cordillera. Keywords: Jurassic, Volcanism, Central Chile, Detrital zircons, Isotopes. 530 The Upper JUrassic volcanism of The río ): insighTs on peTrogenesis... RESUMEN. El volcanismo jurásico superior de la Formación Río Damas-Tordillo (33°-35,5°S): antecedentes sobre petrogénesis, cronología, proveniencia e implicancias tectónicas. Los depósitos continentales y volcánicos delJurásico tardío, pertenecientes a la Formación Río Damas-Tordillo, representan un período de intensa sedimentación continental dentro del registro mayormente marino observado en la Cuenca Neuquina, durante el Jurásico y Cretácico Inferior. Datos estratigráficos y geocronológicos indican una progresiva emersión del dominio de arco y antearco, desconectando finalmente a la cuenca de trasarco del océano Pacífico durante el Jurásico Superior. Este cambio en la configuración del margen tuvo como resultado el desarrollo de una regresión marina y posterior sedimentación continental en la cuenca de trasarco. La fuente de sedimentos más probable habría sido el arco jurásico, ubicado hacia el oeste de la cuenca. La edad máxima de 146,4±4.4 Ma, obtenida en una arenisca roja inmediatamente por debajo de las rocas volcánicas, confirma las edades máximas de depósito titonianas, asignadas ...

Late Jurassic back‐arc extension in the Neuquén Basin (37°S): Insights from structural, sedimentological and provenance analyses

“…The YSG method provides a younger MDA for both samples but is not recommended because single data points can exhibit high errors and the effects of lead loss (Coutts et al, 2019). Therefore, we select the MLA results, consistent with previous geochronologic analyses of the Tordillo and Rio Damas formations Naipauer, Tunik, et al, 2015;Rossel et al, 2014).…”

“…100 km to the east, on the present day Chilean slope of the Principal Cordillera (Figure 1a). The Río Damas Formation igneous rocks have been assigned to subduction-related arc volcanism (Rossel et al, 2014) or retroarc magmatism (Charrier et al, 2007).…”

“…U–Pb geochronological analyses on the Tordillo and Río Damas formations show a maximum depositional age between 151 and 143 Ma for these units (Horton et al, 2016; Junkin & Gans, 2019; Naipauer et al, 2012; Naipauer, Tapia, et al, 2015; Naipauer, Tunik, et al, 2015; Rossel et al, 2014). An ash bed located at the top of the Tordillo Formation ca.…”

The Ancient Configuration of the Southern Central Andes and Paleogeographic Reconstruction of the Late Cretaceous Foreland Basin at 34°40’S

“…Between the Late Jurassic and Early Cretaceous, the deposition of the Mendoza Group took place (Stipanicic, 1969). The first record corresponds to fluvial deposits and volcanic rocks of the Tordillo and Río Damas formations (Figure 2b) (Greco et al., 2022; Rossel et al., 2014). Later, between the Tithonian and the Hauterivian, a new Pacific transgression occurred, represented in Argentina by the thick marine mudstone and limestone deposits of the Vaca Muerta, Chachao, and Agrio formations (Aguirre‐Urreta, 2001; Aguirre‐Urreta & Lo Forte, 1996; Kietzmann & Vennari, 2013; Legarreta & Uliana, 1996) and in Chile by the marine volcaniclastic sequences of the Lo Valdés Formation (González, 1963).…”

“…Between the Late Jurassic and Early Cretaceous, the deposition of the Mendoza Group took place (Stipanicic, 1969). The first record corresponds to fluvial deposits and volcanic rocks of the Tordillo and Río Damas formations (Figure 2b) (Greco et al, 2022;Rossel et al, 2014) Forte, 1996;Kietzmann & Vennari, 2013;Legarreta & Uliana, 1996) and in Chile by the marine volcaniclastic sequences of the Lo Valdés Formation (González, 1963). During the late Early Cretaceous, a new regression caused the continentalization of the basin, represented by the Bajada del Agrio Group (Legarreta & Uliana, 1991).…”