Electrical structure of the lithosphere across the Western Paraná suture zone: the role of a Neoproterozoic-Cambrian subduction in generating the Paraná Magmatic Province

DRAGONE, G. N.; BOLOGNA, M. S.; M. E. GIMENEZ; ALVAREZ ORLANDO; FEDERICO LINCE KLINGER; SEBASTIAN CORREA OTTO; USSAMI, N.

New Orleans

Congreso; American Geophysical Union Fall Meeting.; 2017

American Geophysical Union

The Paraná Magmatic Province (PMP) together with the Etendeka Province (EP) in Africa is one of the Earth?s largest igneous provinces originated prior to the Western Gondwanaland break-up and the inception of the South Atlantic Ocean in the Lower Cretaceous. Geochemical data of PMP-EP basalts collected since late 1980?s indicate the origin of PMP-EP by melting of a heterogeneous and enriched subcontinental lithospheric mantle with fast rate of eruption (< 3 My). The geodynamical cause of this magmatism is still a matter of debate (deep mantle plume x plate model). New isotopic geochemical data from Re-Os systematics (Rocha-Jr et al., 2012, EPSL) of PMP basalts indicate metasomatized asthenospheric mantle component probably generated at the mantle wedge between the PMP-EP lithosphere and the subducting oceanic plate. A combined seismic velocity and density model of PMP by Chaves et al. (2016, G3) indicates high velocity and a density increase of PMP ancient lithosphere interpreted as due to a long-term mantle refertilization process. To investigate the role of the subduction zones in the development of the both the Paraná basin subsidence and magmatic province we present the results of regional scale broad-band MT-magnetotelluric soundings across the western and southern borders of the PMP, the Western Paraná suture zone (WPS in Fig. 1). We discuss the electrical properties of the lithosphere along three MT profiles across the WPS. MT-A profile (Padilha et al., 2015, JGR) extends from Rio Apa craton towards the center of PMP (high-TiO2 basalts). Profile MT-B extends from Tebicuary craton towards the center of PMP (low-TiO2) and profile MT-C extends from Rio de la Plata craton towards the southern PMP (low- and high-TiO2). All profiles show a resistive (~ 104 ohm m) and thick (> 150 km) lithosphere in the cratonic areas whereas the electrical lithosphere is thinner (