Implications of Very Low Electrical Resistivity In The Deep Crust of An Active Thick-Skinned Tectonics In Argentina

University Of Washington, Seattle WA

Investigators

Abstract

Booker 9909390 A recent pilot magnetotelluric (MT) experiment near Tucuman across the eastern Andean deformation front concludes that the lower crust is as electrically conductive as under southern Tibet. Common to both areas is the rate of crustal strain. If one can show that high conductivity is an inevitable consequence of high strain rate one would have a powerful tool for probing active deformation of the deep crust. In collaboration with Argentine colleagues, the investigators are proposing to collect and analyze new MT data to (1) Determine whether very conductive lower crust at Tucuman is a local or regional feature. (2) Elucidate the transition from resistive to conductive crust at the deformation front. (3) Investigate the possibility of shallow asthenosphere in the mantle. (4) Compare Tucuman with two distinctly different regions of the eastern Andean deformation: (a) San Juan, where the crustal strain rate is high, but the subducted slab is very flat and there may be no intervening asthenosphere and (b) Cordoba, the most eastern extent of the flat slab, where crustal strain islow, but kinematics suggests there ought to be an asthenospheric wedge.