Heat flow and lithospheric thickness analysis in the Patagonian asthenospheric windows, southern South America

AVILA, P. Y DÁVILA, F.M.

TECTONOPHYSICS

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2018

0040-1951

The lithosphere-asthenosphere boundary (LAB) is a first-orderdiscontinuity, critical to understand the Earth composition andevolution. However, its detection has been critical and several regionsstill lack of information. The southern Patagonia, in southern SouthAmerica, is one them, which has been affected by the subduction of aseismic oceanic ridge (South Chile Ridge) and formation of an extensiveslab window since ~12 Ma. We calculate the LAB position by defining thethermal lithospheric thickness of the southernmost Patagonia using thethermal conductivity equation to estimate the surface heat flow. We usedseventy-five hydrocarbon well data of two of the most productivepetroleum basins of Argentina: the Golfo de San Jorge and Magallanes-Austral basins. Our results show the highest heat flow values in thesouthernmost region, over the Austral basin and core of the slab window(~70-90 mW/m2). These values are twice hotter than global averages. Tothe north, over de Golfo de San Jorge basin and northern margin of theslab window, heat flows are "normal" (~50-60 mW/m2). These thermalcontrasts, from south to north, agree with the kinematic reconstructionsof the Chile ridge and northward widening of the slab window. These heatflows values evidence an attenuated lithospheres, which thicken eastwardfrom between 25 km (to the west, trench region) to 50 km (to the east,foreland region).