Basins thermal structure in the Pampean flat subduction zone

COLLO, G., EZPELETA, M., DÁVILA, F.M., GIMENEZ, M., SOLER, S., MARTINA, F., ÁVILA, P., SÁNCHEZ-NASSIF, F., CALEGARI, R., LOVECCHIO, J.P., SHCIUMA, M.

The Evolution of the Chilean-Argentinean Andes

Springer International Publishing

Año: 2018; p. 537 - 564

The first geothermal gradient map in the Pampean flat-slab segment of the south-Central Andes and the transitional zones to normal subduction (toward the north and south) is presented in this contribution. The new data is correlated basin-basal heat flow BHF estimated from petroleum exploration borehole data, Curie point depths (CPD) derived from aeromagnetic surveys and crustal and lithospheric thicknesses. Studies show that changes in the sedimentation histories of the analyzed basins is not sufficient to explain the recorded variations in the geothermal gradient, and changes in the basal heat fluxes are needed. The map distribution of geothermal gradient data and thermal modelling results in the Argentine flat-subduction segment evidence a quite good consistency and correlation among them. Regional variations, with the coldest basins over the flat-slab or towards cratonic areas and basins with the highest temperatures developed on pluging-slab areas, show that the flat slab geometry as well as the lithospheric structure strongly affect the thermal state within the upper crust and particularly the sedimentary basins. Further studies will allow improving our database as well as the knowledge about the contribution of the lithosphere radiogenic heat and the asthenospheric heat to the basins basal heat flow.