A Preliminary Crustal Geophysic model at 29º18' South latitude based on the observed Bouguer anomaly

MARTINEZ, M PATRICIA; GIMENEZ, MARIO E

Barcelona

Congreso; ISAG (6th International Symposium on Andean Geodynamics, Universitat de Barcelona, 12-14 Sept., 2005); 2005

ISAG

The present article describes a gravi-altimetric profile that extends over a distance surpassing 800km in Argentina, at 29º18’ South Latitude.. Using gravimetric inversion methods a crustal model was obtained which is in accordance with the main regional geologic structures. This model fits with a dominant collision mechanism that affected ancient blocks. It is a simple cortical model with two crust layers and which involves lateral density variations. Bearing in mind the subhorizontal subduction system of the Nazca plate, the Chilenia, Cuyania, Famatina System, Pampia and River Plate cratons can be detected. The gravimetric signal indicates beyond doubt the suture zone between the Precordillera and the Famatina System Ranges, as well as the shear zone between the latter ranges and the Velasco Range. The maximum crustal thickness determined beneath the Andean Cordillera at this latitude is 69 km, whereas under the Famatina System and the Velasco Ranges the values obtained are, respectively, 56 km and 46.5 km.