Artículos de revistas
Electromagnetic constraints for subduction zones beneath the northwest Borborema province: evidence for Neoproterozoic island arc–continent collision in northeast Brazil
Fecha
2014Registro en:
Geology, Boulder, v. 42, n. 1, p. 91-94, 2014
doi:10.1130/G34747.1
Autor
Padilha, Antonio L.
Vitorello, Ícaro
Pádua, Marcelo B.
Bologna, Mauricio de Souza
Institución
Resumen
The Borborema province in northeast Brazil occupies a crucial position in the complex Neoproterozoic
West Gondwana reconstruction puzzle. However, correlation attempts between
northeast Brazil and West Africa have been hampered because key links in the internal structure
of the Borborema province have yet to be identifi ed. To aid such an correlation, a magnetotelluric
study was undertaken along two subparallel profi les to image the deep electrical
structure in the northwestern part of the province. Despite the occurrence of recurrent tectonothermal
episodes that affected the region in the past, two-dimensional models show that
a large-scale signature of the assembled terrane during the Neoproterozoic accretion and collision
is plausibly preserved in the area. Two resistive features dipping from the upper crust
into the upper mantle in downward convergence (opposite directions) are defi ned beneath one
of the profi les that are interpreted to be related to remnants of former subduction slabs, since
the observed high-resistivity zone is consistent with a dehydrated oceanic lithosphere depleted
of sediments. On the basis of geological and geochemical information, a model of collision of
an intraoceanic magmatic arc coalesced into an earlier passive margin is proposed for the
Neoproterozoic tectonic evolution of the province, involving processes of reversal of subduction
polarity and oceanic slab breakoff.