A zona tectônica Teixeira Terra Nova - ZTTTN: fundamentos da geologia regional e isotópica

Abstract

A sigmoidal-shape linear tectonic zone occurs from Teixeira (Paraíba, to the north-northeast)- to Terra Nova (Pernambuco, to the south-southwest) as a line diagonal to the"Transversal Zone", which is the central tectonic portion of the Borborema Province, thus dividing this province into two different litho-structural and tectonic domains. To the north and northwest occur the Early Neoproterozoic Riacho Gravatá (RG) and the Neoproterozoic Piancó-Alto Brígida (PAB) terranes, both of them characterized by supracrustal rocks with low-grade of regional metamorphism. To the south-southwest occur the Alto Pajeú terrane (TAP, Early Neoproterozoic, orthognaisses and mesozonal supracrustal rocks) and the domain of its basement, the Alto Moxotó terrane (TAM, Paleoproterozoic in age), with high grade metamorphic rocks. This proposed"tectonic zone" is mostly composed by orthogneisses (from TAP and its Paleoproterozoic basement) pierced by an almost continuous series of intrusive granitic and syenitic rocks (plutons and stocks) of the Ediacaran period (ages between 630 and 570 Ma). During the evolutionary history of this linear portion of the plateau of the Borborema province there are some (direct and indirect) records of polycyclic geologic events of the Paleoproterozoic, Early Neoproterozoic, Ediacaran, Cambrian and Cenozoic era (a sedimentary veneer, evolution of a supergenic crust and regional uplift) with interesting implications for the regional geology, geography and social-economic development. In this paper the emphasis will be given to the isotopic data (Rb-Sr, Sm-Nd, mostly) along this special zone and the domains that it separates, as well its role on the regional tectonic framework. For this purpose, we take into consideration an expressive amount of available geological and isotopic data, obtained along the last decade (most of them not published) from different sources. Additionally, some first interpretative hypotheses will be postulated, where this tectonic zone (ZTTTN) would be formed as by-product of three parallel Neoproterozoic subduction zones.