Curie Point Depth and thermal flux in the offshore basins zone of Argentina

  • Guillermo Domingo Pizarro Universidad Nacional de San Juan (UNSJ), Facultad de Ciencias Exactas, Físicas y Naturales, Instituto Geofísico-Sismológico Ing. F. Volponi (IGSV). Ruta 12, km 17, C.P. 5407, Jardín de los poetas, Marquesado, Rivadavia, San Juan, Argentina.
  • Francisco Ruiz Universidad Nacional de San Juan (UNSJ), Facultad de Ciencias Exactas, Físicas y Naturales, Instituto Geofísico-Sismológico Ing. F. Volponi (IGSV). Ruta 12, km 17, C.P. 5407, Jardín de los poetas, Marquesado, Rivadavia, San Juan, Argentina.
  • María Alejandra Arecco Universidad de Buenos Aires, Facultad de Ingeniería, Instituto de Geodesia y Geofísica Aplicadas. Universidad de la Defensa Nacional, Facultad de la Armada, Escuela de Ciencias del Mar.
  • Marta Ghidella Ministerio de Relaciones Exteriores y Culto, Cancillería Argentina, Instituto Antártico Argentino.
Keywords: Isostatic decompensation, CPD, thermal flow, offshore basins, gravimetric Moho

Abstract

In order to know the thermal distribution and its relationship with tectonic structures studies were conducted in front of the Argentine coast, in the area corresponding to the platform, slope and abyssal plain, in the region ranging from 50° to 66° West and 36° to 50° South. Fourier analysis of the potential fields allows us estimating the Curie point depth (CPD). The variation of the depth to the Curie point is an indicator of lithospheric thermal anomalies, some of which would be associated with variations in lithospheric thickness linked to the phenomena that took place during the separation of the Gondwana continent and opening of the South Atlantic Ocean, such as basins and transfer zones. Maps of Curie point depth and thermal flow were made. These maps were correlated with an isostatically compensated crust 3D model and a crust-upper mantle discontinuity depth 3D model, calculated by gravimetric inversion. This comparative analysis allowed us to interpret tectonic structures, crustal thickness and isostatic decompensation degree on the study area. Higher depths to the Curie point were obtained in the continental crust zone (between 30 and 15 km, approximately) than in the oceanic zone (between 25 and 10 km, approximately). On the continental crust, the shallowest values ​​were found in the offshore basins sectors, in the oceanic crust, the deepest values are below the crust-upper mantle discontinuity level. Offshore basins are associated with lithospheric thinning accompanied by thermal anomalies indicated by elevations of the CPD. The oceanic basement would be linked to descending asthenospheric currents that produce an increase in its depth and CPD. The isostatic model shows a deeper mantle than the gravimetric one in sectors of offshore and shallow basins in the oceanic crust zone. The isostatic model shows a deeper mantle then the gravimetric one in the offshore basins sectors and shallower in the oceanic crust zone.

Published
2020-03-31
Section
Articles