Two-stage terrane assembly in Western Gondwana: Insights from structural geology and geophysical data of central Borborema Province, NE Brazil

Abstract

28Combined geophysical and structural data from the Transversal Subprovince of the The terrane boundary is delineated by the Serra de Jabitacá Shear Zone, which is

Accretion Tectonics in Western Gondwana Deduced From Sm‐Nd Isotope Mapping of Terranes in the Borborema Province, NE Brazil

“…The distribution of T DM model ages and range of εNd (t) from the metaplutonic and metasedimentary rocks of the Meso‐Neoproterozoic Alto Pajeú terrane and Archean‐Paleoproterozoic Alto Moxotó terrane of the Borborema Province are distinct (Figures ). The changes in values correspond with the surface trace of the Serra de Jabitacá Shear Zone, which delineates the boundary between the two terranes (Brito Neves et al, ; Santos, Dantas, Vidotti, et al, ; Santos & Medeiros, ). This suggests that the terrane boundary is a steeply dipping feature that penetrates the crustal section of the region.…”

“…The documented patterns on Nd distribution presented in this paper indicate two distinct isotopic reservoirs, thus reflecting distinct crustal sources for the studied terranes. Recent regional compilations and geophysical and structural data also help to infer that they correspond to distinct lithospheric fragments (Padilha et al, ; Santos, Dantas, Vidotti, et al, ; Van Schmus et al, ). In addition, if we take into account the Nd compositions of metasedimentary sequences to the north and south of the proposed terrane boundaries, it is clear that they also present distinct source ages, thus indicating derivation from different precursor sources.…”

“…The obtained data allow us to reconstruct the main events that affected both terranes (Figure ). In the Alto Moxotó Terrane, TTG rocks dated at 2.6 Ga (Santos, Dantas, Vidotti, et al, ), such as the Riacho das Lajes Suite, present positive to slightly negative εNd (t) values and T DM model ages ranging from 2.7 to 2.9 Ga. This likely indicates juvenile magmatism in the region, in spite of some reworking of a previously formed Archean crust.…”

“…The plutonism is considered syntectonic and widespread throughout the Transversal Sub‐province from 630 to 580 Ma, recording a complete magmatic arc system (Brito Neves et al, ). Also, within this terrane, the previous Tonian fabric is strongly reworked by Brasiliano tectonics resulting in a complex mosaic of NE‐SW curvilinear transcurrent to transpressional shear zones (e.g., Santos, Dantas, Vidotti, et al, ).…”

“…As well as other important structures within the Borborema Province, latter strike‐slip tectonics overprinted previous fabrics, including thrust markers related to the Serrá de Jabitacá Shear Zone. Recent geophysical and structural analysis has suggested that thick‐skinned tectonics resulted in frontal to oblique assembly between the Alto Moxotó and Alto Pajeú terranes via tangential tectonics of the Serra de Jabitacá Shear Zone (Santos, Dantas, Vidotti, et al, ).…”