masterThesis
Assinatura estrutural e geofísica da porção norte (fronteira Ceará-Piauí) no lineamento transbrasiliano: reativação na bacia do Parnaíba
Fecha
2015-05-25Registro en:
CACAMA, Moisés Samuel João Bota. Assinatura estrutural e geofísica da porção norte (fronteira Ceará-Piauí) no lineamento transbrasiliano: reativação na bacia do Parnaíba. 2015. 90f. Dissertação (Mestrado em Geodinâmica e Geofísica) - Centro de Ciências Exatas e da Terra, Universidade Federal do Rio Grande do Norte, Natal, 2015.
Autor
Cacama, Moisés Samuel João Bota
Resumen
The Transbrasiliano Lineament is a major shear zone trending NE-SW, related to the Brasiliano
orogeny and evolved through high to low temperature stages. In this study, the structural and
geophysical signature of the northern segment of Transbrasiliano Lineament was studied in its
northern border, between Ceará and Piauí states, involving the Brasiliano mylonite zone, the
Jaibaras Graben and reactivations affecting the sedimentary sequences post-ordovician of
Parnaíba Basin. In the literature, is commonly the phanerozoic reactivation of this structure
referred, generating several late Brasiliano grabens predating the paleozoic Parnaíba syneclises,
like the Jaibaras Graben. Faults that cut the stratigraphic units of the Parnaíba Basin along the
entire length of the Transbrasiliano Lineament express its reactivation during younger events.
The magnetic anomaly field reduced to the pole map exhibit anomalies NE-trending, interpreted
as the signature of the Transbrasiliano Lineament (and Brasiliano structures of the Borborema
Province) in its high-temperature expression. The Jaibaras Graben is marked by a straight
anomalous track with high magnetic susceptibility (interpreted as a prevalence of ferromagnesian
rocks, probably volcanic), apparently without significant continuity in the substrate of Parnaíba
Basin. The geometric and kinematic analysis of the structures in the study area, using remote
sensing and field data, led to the characterization of four deformation phases brittle the ductilebrittle
Dn, D1, D2 and D3. The Dn deformation phase of ediacaran-cambrian age, occurs
exclusively in the Jaibaras Graben, with the development of comparatively higher temperature
(as regards to younger events) ductile-brittle structures. D1, D2 and D3 deformation phases affect
both the Jaibaras Graben as well as the paleozoic sequences of the northeastern edge of Parnaíba
Basin, generating structures developed at lower temperatures, basically brittle/cataclastic. The
SRTM image analysis allowed mapping different NE, NW and E-W trending lineaments in
Parnaíba Basin, whose correlation with mesoscopic structures is discussed in terms of the
reactivation of Transbrasiliano Lineament in association with the stages of general Atlantic
opening and separation between South America and Africa, or even the distal orogenic events in
Paleozoic.