The Paleozoic Claromecó Basin (Argentina): 3D lithospheric scale density model.

SEBASTIAN VAZQUEZ LUCERO; CLAUDIA PREZZI; MAGDALENA SCHECK-WENDEROTH; BOTT, JUDITH; MARÍA LAURA GÓMEZ DACAL; H. VIZAN; FLORENCIA BALLESTRINI

Congreso; Latin American Colloquium of Geosciences; 2019

The Paleozoic Claromecó basin (located to the southeast of Buenos Aires Province between ~37°-39° S and 61°-63° W) has been subject of multiple geological and geophysical studies. Different hypotheses and mechanisms have been proposed for the genesis of this basin, as well as for the deformation of the Australes Ranges.The sedimentary infill of the basin partially outcrops in the Australes Ranges, where three Paleozoic sedimentary groups have been identified.The principal goal of this work, is to contribute to a better knowledge of the Claromecó basin evolution on the basis of the development of a lithospheric scale 3D gravity forward model. Geological information, global gravity model EIGEN6C4, well data (Lesta and Sylwan, 2005), Moho depth from seismic tomography, and pre-existing 3D models of the Colorado basin (Autin et al., 2016) were used for the model construction. IGMAS+ software was used to develop our model. To fit the modeled gravity anomaly to the measured one, it was necessary to set as free parameters the lower and upper crust top layers, which geometries were accordingly modified.Constant densities for each unit are required for the calculation of the measured gravity in IGMAS+. We used the same values of the Colorado area in Autin et al. (2016) model, and the bulk density values published for the Claromeco Basin sediments (Achilli and Kostadinoff, 1985).Our model allowed to gain insight into the Moho depth, the variations of the thickness of the sedimentary infill and the upper and lower crust, in the studied area. We propose a tentative location of the southern limit of the Rio de la Plata craton. Our results also contribute to the understanding of the geodynamic evolution of Claromecó basin and of the tectonomagmatic processes which affected the southwestern margin of Gondwana during Paleozoic times.