Petrographic Control on the Geomorphological Evolution of the Quixeramobim River Batholith, Northeastern Brazil

Resumo

Petrographic control has a strong influence on the geomorphological evolution of granitic plutons in the Borborema Province (Northeast Brazil), which are made up of varied natures, shapes and dimensions. The Rio Quixeramobim Batholith, located in the Central Ceará Domain, is conditioned by the dextral shear zones of the NE direction, Quixeramobim and Senador Pompeu and is constituted by six distinct granite suites. This work aims to analyze the geomorphological aspects of the Rio Quixeramobim Batholith, based on petrographic (mineralogical and structural) analyses, correlating the morphologies with the different suites analyzed. The methodology consisted of analysis of geological and geomorphological data, field investigations, sample collection and analysis in a microscopy laboratory. Geomorphological features are strongly related to
mineralogical and structural characteristics, associated with the degree of microfracturing of their constituent minerals. The data show that, in addition to mineralogical diversity, structural aspects such as the degree of microfracturing, porosity and texture are fundamental for the development of granitic macro and microforms. Furthermore, the NE-SW trending structural control is also fundamental in the geomorphological diversity, showing an aligned arrangement of inselbergs at the edges of the batholith, as a result of pre-defined structural patterns.