Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5113513 | Quaternary International | 2017 | 16 Pages |
Abstract
We investigate the role of reactivation of Precambrian basement fabric in the tectono-sedimentary and geomorphological evolution of the ParaÃba Basin, continental margin of northeastern Brazil, during the Cretaceous, Neogene, and Quaternary. This basin represents part of the last bridge between South America and Africa before the last breakup stage of the South Atlantic rifting in the early Cretaceous. The ParaÃba Basin infill is composed of siliciclastic and carbonate Cretaceous units, as well as aeolian, fluvial and marine Quaternary units. We used shuttle radar imagery, aeromagnetic, wellbore and field data. The reduced-to-the-pole magnetic map (RTP) indicates the continuity of the steeply dipping Precambrian basement shear zones beneath the ParaÃba Basin. The combined analysis of surface and subsurface data shows that NE-SW and E-W-striking shear zones were subjected to brittle reactivation in the Aptian-Middle Albian during the basin opening and again in the Neogene-Quaternary, forming a system of horsts and grabens along the basin; some of these structures such as the E-W-oriented Pernambuco shear zone present modern-day seismicity. N-S- and mainly NW-SE-striking transfer faults cut across Aptian-Middle Albian to Neogene-Quaternary strata. These four main fault directions control main river channels and alluvial valleys up to 2Â km wide. Topographic breaks up to 50Â m were created by late reactivation of rift faults, which mark the boundary between horsts and grabens along the basin. In addition, structural data evidence syn-tectonic faulting with vertical offsets up to 80Â m in the Cretaceous and up to 70Â m in the Neogene-Quaternary. We conclude that shear zones across the study area are long-lived structures that have behaved as weakness zones. Their neotectonic brittle reactivation has controlled sediment deposition and landform development, which continued through the Neogene-Quaternary.
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Geology
Authors
Jean C.F. Lima, Francisco H.R. Bezerra, Dilce F. Rossetti, José A. Barbosa, Walter E. Medeiros, David L. de Castro, David L. Vasconcelos,