Geodynamics of the Lomas de Olmedo subbasin, northeastern Argentina, interpreted from a local compensation model and statistical analysis of gravimetric data

  • Héctor Pedro Antonio García Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) Argentina. Instituto Geofísico Sismológico Ing. Volponi. Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de San Juan, Ruta 12, km 17, C.P. 5407, Jardín de los poetas, Marquesado, Rivadavia, San Juan, Argentina.
  • Federico Lince Klinger Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) Argentina. Instituto Geofísico Sismológico Ing. Volponi. Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de San Juan, Ruta 12, km 17, C.P. 5407, Jardín de los poetas, Marquesado, Rivadavia, San Juan, Argentina.
  • Mario Ernesto Giménez Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) Argentina. Instituto Geofísico Sismológico Ing. Volponi. Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de San Juan, Ruta 12, km 17, C.P. 5407, Jardín de los poetas, Marquesado, Rivadavia, San Juan, Argentina.
  • Francisco Ruiz Instituto Geofísico Sismológico Ing. Volponi. Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de San Juan, Ruta 12, km 17, C.P. 5407, Jardín de los poetas, Marquesado, Rivadavia, San Juan, Argentina.
Keywords: gravimetry, isostasy, Lomas the Olmedo trough, Geodynamics.

Abstract

The Lomas the Olmedo trough is locatedwithin the Chaco-Bonaerense plain. It has a southwest-northeast trend and is one of the depocenters of the cretaceous-paleogene basin (northwestern Argentina). This trough is a typical continental rift basin in the sense of "triple junction point". The isostatic state of Lomas the Olmedo trough was evaluated through the Airy-Heiskanen’s isostatic compensation model and the statistical analysis of the gravity anomalies. 

The Airy-Heiskanen model was used to derive an hydrostatic Moho map of the study area. This hydrostatic Moho includes the root that compensates topography and the anti-root from Lomas the Olmedo trough, which hosts a thick sedimentary column of nearly 6 kilometers. Additionally, the local isostatic anomaly was calculated. It was made, affecting the Complete Bouguer anomaly by a geological correction or correction for sediment and then by the gravimetric effect of the hydros- tatic Moho. An extensive negative isostatic anomaly covering most of Lomas the Olmedo trough was identified. According this compensation model for the depocenter, this anomaly may indicate that the depocenter is isostatically sub-compensated or that there is a deficit of anti-root. The sub-compensation state was also observed through statistical regressions between Complete Bouguer anomalies and topographic altitudes.

Published
2018-01-04
Section
Articles