Mapeamento geológico de parte das unidades Canindé e independência no distrito de Manuel Pereira, município de Canindé-CE

Abstract

This work deals with the geological mapping conducted in scale of 1: 25,000 in an area of 54 km2, southwest of the town of Caninde, in the district of Manoel Pereira, backwoods of Ceará State Central. It aims at making a geological map, one macroscopic and microscopic petrographic detailing, definition of tectonic setting and geological evolution. Two lithostratigraphic units belonging to the Ceará Complex were recognized: the Caninde Units and Independence undoubtedly metamorphic, carrying migmatitic features. The Independence Unit consists of amphibolites, metatexitos the amphibole and calcissilicáticas where anfibolititos are formed from the metasomatism of marbles. The subsequent partial melting of these anfibolititos resulted in amphibolites training and metatexitos the amphibole in the latter case leaving calcissilicáticas as restitos. The Caninde Unit makes up most of the area and is made up of schists, metatexitos biotite, leucogranite and mylonite (leucogranite and metatexitos). The partial melting of biotite schists produced the metatexitos, diatexitos and leucogranite. Four patterns of foliation Sn, Sn_t and Sn + 1 were identified, and the main Sn, characterized by a banding migmatitic having N-S trend variable dips from 40 to 80 °, generally east. Mylonites mark the existente of a ductile shear zone, the direction N-S, probably the continuity of Paramoti shear zone. These mylonite exhibit Lx ranging from 30 to 80 ° and sense of trim consistent with the direction of dip of the foliation. Lx these values suggest a ductile shear zone characterized by a transcurrent movement (dextral) with a strong push component with tectonic transport direction southwest. Silexitos, pegmatites and basalts occur as late bodies cutting other lithologies, where basalts belong to Magmatism Ceará Mirim. The general anatexia suggests a regional metamorphic metamorphic peak with the highest amphibolite and granulite facies with temperatures ranging from 650 to 850 ° C and pressures ranging from 4 to 12 kbar. The region is interpreted as a continental shelf, formed by the merging of sandstone, clay and carbonate rocks, where the portions are represented by argillaceous schists and biotite metatexitos. Although not have geochronological data, the absence of deformation in leucossomas of migmatites suggest a Neoproterozoic age for the metamorphism these rocks.