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Title

Lithospheric thinning under the Araripe Basin (NE Brazil) from a long-period magnetotelluric survey: Constraints for tectonic inversion

AuthorsGarcía, Xavier ; Julià, Jordi; Nemocon, Ana Milena; Neukirch, Maik
KeywordsAraripe Basin
Asthenosphere
Basin inversion
Borborema Province
ConductivityLithosphere
Magnetotellurics
Partial melt
Issue DateJan-2019
PublisherElsevier
CitationGondwana Research, 68: 174-184 (2019)
AbstractThe lithospheric architecture of the western Borborema Province and northern São Francisco craton of NE Brazil has been investigated through analysis of long-period magnetotelluric data acquired along a 700 km long survey, using 12 instruments. The survey samples several tectonic terrains in the Province and penetrates into the adjacent São Francisco craton after crossing the Araripe Basin, an aborted rift basin filled with Mesozoic sediments that peak at ∼1000 m above mean sea level. High conductivities are observed at shallow depths under the main Precambrian shear zones that pervade the Province – consistent with tectonic reactivation – and as a small patch embedded within the high resistivities that characterize the São Francisco craton. High conductivities (∼25 Ωm) are also observed below 120 km depth between the Patos and Pernambuco lineaments – right under the Araripe Basin – flanked by resistive (>120 Ωm) material immediately to the north and south. This deep, highly conductive body is found consistent with the presence of melt and aqueous fluids, and is interpreted as shallow asthenospheric mantle bounded by thicker lithosphere. We propose that extensional stresses in the Mesozoic stretched and thinned the lithosphere under the Araripe Basin, causing passive upwelling of asthenospheric material and lateral flow of the overlying lithosphere, and resulting in thickening of the lithosphere under the flanks and uplift of the Araripe Basin. We also hypothesize that thermal weakening of the lithospheric mantle – perhaps sustained by channeling of asthenospheric flows under the basin – would have caused regional stresses to concentrate in the brittle upper crust and contribute to basin inversion. We thus propose that a combination of localized horizontal stresses and vertical buoyancy from underlying asthenospheric material are ultimately responsible for the actual topography of the Araripe Basin. © 2019 International Association for Gondwana Research.
Publisher version (URL)https://doi.org/10.1016/j.gr.2018.11.013
URIhttp://hdl.handle.net/10261/174628
DOIhttp://dx.doi.org/10.1016/j.gr.2018.11.013
ISSN1342-937X
E-ISSN1878-0571
Appears in Collections:(Geo3Bcn) Artículos
(ICM) Artículos
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