Abstract
The P-Li-Nb pegmatites are located in the south of Brazil, in the states of Minas Gerais and Espirito Santos. They represent the largest pegmatite fields of Brazil and the richest in precious stones. Two types of pegmatites are characterized by their mineralogical characteristics and tectonic and magmatic relations. The first group occurred during a compressive deformation phase D1 about 582 Ma and 550℃ - 700℃ and 4 - 5 kb. The second pegmatites group was formed during the decompression phase D2 (520 - 500 Ma) of the Brasiliano metamorphic rock fusion. The geochemical parameters of the P-Li-Be bearing pegmatites of the first group show the same trend fractionation, as suggested by the mineralogical composition. The variation of tourmaline and columbite-tantalite composition of the first group game again applies a change of melt composition during the regional development of the pegmatites. A systematic compositional trend seems to suggest a petrogenetic link between the pegmatites of the region. The Fe/Mn ratio of tourmaline in samples of the first group shows the same behavior as in columbite-tantalite and garnets. The simple pegmatites are transiting north in the gem-rich pegmatites. The Fe/Mn ratio not only shows qualitatively the fractionation index, the degree of regional development, but also the internal development of the body. The ratio shows a negative correlation with lithium. The Co, Zn and Nb contents are rising at first group, but falling when starting crystallization of garnet, columbite-tantalite, and Behierit.
Highlights
The Doce River region is located in the central northern part of the Mantiqueira Structural Province, east of São Francisco carton in the eastern Minas Gerais and northwestern Espírito Santo states (Figure 1)
The variation of tourmaline and columbite-tantalite composition of the first group game again applies a change of melt composition during the regional development of the pegmatites
A systematic compositional trend seems to suggest a petrogenetic link between the pegmatites of the region
Summary
The Doce River region is located in the central northern part of the Mantiqueira Structural Province, east of São Francisco carton in the eastern Minas Gerais and northwestern Espírito Santo states (Figure 1). This province is represented by Neoproterozoic mobile belts that surrounded the São Francisco cratonic block and is associated to the Brazilian orogeny (600 - 450 Ma). The first deformation (D1) was responsible for penetrative foliation (solid state) N 10 ̊W - 30 ̊W/middle to high angle and mineral lineation of the host rocks and the granitoids It affected pre-tectonic granites and controlled magmatic foliation the sin-tectonic granitoids. The recent geochronology study demonstrates existence of two tectono-metamorphic events in this region dated at 590 - 565 Ma and 535 - 520 Ma [2,3,4,5,6,7,8]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
