Identification of precambrian deformational phases in the region of Tejuçuoca - CE

Abstract

We present new data obtained in a detailed geological survey carried out in Tejuçuoca-CE. The study area is located in the Central Ceará domain, 30km southeast of the Santa Quitéria Magmatic Arc (SQMA), where the rocks of the Canindé Complex of Ceará (Paleoproterozoic) and the Ceará Group (Neoproterozoic) predominate. Field data and petrographic studies were integrated with geoprocessing of satellite imagery and aerogeophysical data to produce a detailed lithostructural geological map. The cartography generated, together with the analysis of the structural data, allowed the identification of four phases of deformation that mark the Precambrian tectonic evolution in the region, the last three being correlated with specific episodes of the Brasiliano cycle. Phase D1 represents a pre-Brasilian deformational event, which originated a past foliation later reworked in the subsequent phases. Phase D2 is related to the initial collisional stages of the Brasilian Orogeny, involving the generation of structures with orientation parallel to the axis of the SQMA. The D3 phase is linked to the advanced collisional stage of orogenesis, where tectonics dominated by thrust faults associated with internal deformation processes, reoriented the foliation. Finally, phase D4 is related to the development of transcurrent tectonics, which represented a post-collisional stage of reaccommodation of the spaces occupied by the rock masses.