3D Lithospheric-Scale Density and Thermal Model of the Claromecó and North-Colorado Basins, Argentina

GÓMEZ DACAL, MARÍA LAURA; SCHECK-WENDEROTH, M.; VÁZQUEZ, SEBASTIÁN; PREZZI, CLAUDIA BEATRIZ; VIZÁN, HAROLDO; IBARRA, FEDERICO; BOTT, JUDITH

Simposio; AAPG Virtual Research Simposyum Latin America and Caribbean Region South Atlantic Basins; 2020

AAPG

The study area is located to the southeast of Buenos Aires Province between 36°- 39° S and 63°- 57° W and encompases different morphotectonic units: Sierras Australes in the south-mid western area, the Claromecó Basin in the middle, the Tandilia Terrane in the northeast, and the Colorado Basin in the south (Fig. 1). Several attempts have been made to study and analyse the onshore and offshore features of the Colorado and Claromecó Basins, due to its hydrocarbon potential.The sedimentary infill of the Claromecó Basin involves an early Paleozoic stage of passive margin deposition, which includes quartzites and sandstones as main lithologies (Curamalal and Ventana Groups). On the top of these marine sequences, the glaciomarine Sauce Grande Fm. (basal unit of the Lower Pillahuincó Group) was discordantly deposited. Finally, the stratigraphic record is completed with the shales of the Tunas Fm. (basal unit of the Upper Pillahuincó Gp.), which register a typical configuration of a foreland basin syn-orogenic clastic wedge. This foreland basin tectonic scenario is attributed to the Late Permian Gondwanides orogeny, which coincides geochronologically with the deposition of the Tunas Fm.On the other hand, the genetic evolution of the Colorado Basin, was strongly influenced by lower crustal magmatic intrusive bodies. The emplacement of such intrusions was interpreted by several authors to be related to previous crustal heterogeneities, assumed to be regional transfer zones which cut across the whole continental platform.In this context of different hypotheses and mechanisms proposed for the genesis of these basins, as well as for the deformation of the Sierras Australes, we developed 3D lithospheric scale gravity forward and thermal models. Firstly, we aimed to contribute to a better knowledge of the sedimentary distribution of the Claromecó Basin and its thermal state. Secondly, we attempted to gain insight into the tectonic setting and evolution of the studied area.To set up the 3D thermal conductive field, the 3D density configuration was firstly derived, which corresponds to the one published by Vazquez Lucero et al. (2020; Fig. 2). Such 3D density configuration integrated geological information, a global gravity model (EIGEN 6c4), published well data, seismic tomography data and pre-existing 3D density models of the Colorado basin (Autin et al., 2016).We used the software IGMAS+ to develop our model and fit the measured gravity, by modifying the free parameters: the lower and upper crust top layers.