Mapeamento geológico do Pegmatito Alto do Tibiri: aspectos estruturais e mineralógicos

Abstract

The Alto Tibiri is a pegmatite body located in the southern region of the Rio Grande do Norte, in Parelhas city, geologically inserted in the Borborema Pegmatite Province and occur intruding the mica schists of the Seridó Formation. Currently, both mica and feldspar are commercially exploited in this pegmatite body. In the field missions, 39 outcrops were described, in each one the main texture and mineralogical aspects of the outcropping rock were described. The geological mapping has allowed us to distinguish two types of schists, based on content and size of the mineral phases. There is a garnet rich schists and other with a relevant cordierite content. The studied region shows narrow pegmatite dykes, composed of quartz, feldspar, muscovite and/or biotite and black tourmaline, these dikes were classified as homogeneous. It’s possible to observe in Alto Tibiri a welldefined mineral zoning, as follows: i) border area, marked by the abundance of muscovite; ii) Zone II, composed of quartz, feldspar and mica, in which the main mineral resources occur (tantalite, spodumene, apatite, etc.) and iii) quartz pockets. The observed mineral zoning is similar to that described as mixed traditional pegmatite bodies.