Caracterização Mineralógica de Granada-gnaisse e granulitos máficos da área de Cruzeiro do sul, Domínio Bacajá, Província Transamazonas

Abstract

This work has as main objective the chemical and mineralogical characterization of minerals present in garnet-gneiss and granulite rock types. With this, will focus on results of studies of mineral chemistry by SEM (scanning electron microscopy) and x-ray diffraction in the garnet minerals, plagioclase, biotite, pyroxene and cordierite. Analyzes were made in samples of metamorphic rocks of garnet-gneiss and granulites outcrop in Vila Cruzeiro do Sul, southern portion of Bacajá Domain, Transamazonas Province. The grenades were found to be almandine composition and espessatita charge respectively, pyroxenes were classified as ferrosilite in garnet-gneiss, and the clinopyroxene granulites were classified as augite and subordinate pigeonite and orthopyroxene enstatite the ferrosilite. The plagioclase shows oligoclase composition in garnet-gneiss, with the presence of plagioclase lamellae antipertita oligoclase composition, antipertita pertíticas presents lamella seen in orthoclase SEV-sample 18A. The granulocytes showed plagioclase composition of oligoclase. The garnet-gneiss of upside and granulocytes showed up in the field of phlogopite and annita in SEV-18A sample. The association ferrosilite + cordierite, staurolite + biotite, staurolite + grenade, antipertita and the Ti content in biotite indicates metamorphism of granulite facies conditions, with temperatures of 700ºC order and intermediate pressure. However this work is far from providing all data and sufficient information on the evolution and metamorphism of Bacajá domain, however is the beginning of many other works that can be done to unravel the processes of formation of these rocks.