Electrical conductivity beneath the Andean back-arc in Argentina near 36.5 S

A. BURD, J. BOOKER, A. FAVETTO, M. C. POMPOSIELLO, G.GIORDANENGO.

El Vendrell España

Workshop; 18th International Workshop on Electromagnetic Induction in the Earth; 2006

S. Mendoza Province, south of the Nazca flat slab, has widespread recent basaltic volcanism, but no historic activity. Over the last 1 MY, the basalt has evolved from having a slab signature to OIB. In early 2005, we collected 18 MT sites from 67 to 70 W along 36.7 S, near the large caldera Pay´un Matr´u. For a subset of these significantly 3D data, we can justify a regional strike determined from phase tensors and induction vectors of about N 19 W at periods below 200 s and N 33 W at longer periods. Minimum structure 2D inversions of both period ranges imply resistive crust except near the surface. There is no high conductivity clearly causally related to the basaltic volcanism. At the west end of our profile there is lower crustal to upper mantle conductivity that decreases and deepens eastward, which seems more likely to be related to the active Andean volcanic arc.