Petrografia, geoquímica e geocronologia da Suíte Intrusiva Noroagro, divisa Mato Grosso – Rondônia, SW do Cráton Amazônico

Abstract

The area is localized in the Comodoro District (MT). The basement is constituted by metavolcanosedimentary rocks, paragneiss, paramphibolites and schists. Meeting under Complex “Rio Galera” denomination, flagging in the central portion. This rocks presents complex deformational pattern showing three penetrative foliations being the S1 and S2 coaxial, and the strike 70-80ºW and medium to high dip. In this works, the rocks previously denominated Granite Rio Piolho are approach with the assignment of Suite Intrusive Noroagro (SIN) homonymous of District. The SIN is composed by holocrystalline, inequigranular, medium to coarse grained,xenomorphic, gray color, with plagioclase, quartz, hornblende, biotite (primary mafic minerals) and microcline (rare). The alteration minerals are: zoizite, sericite, calcite, epidote and clay minerals. Chemically shows composition ranging from tonalite to monzogranite being the parental magma classified as sub-alkaline and calc-alkaline type, generated in volcanic arc environment at the post-orogenic time. The metamorphic process suffered by this rocks, occur in straight association with the F3 deformational pattern. The isotopic data obtained (sample RM-1) by the Pb/Pb method refers to the medium age 1421.2 +4.7 Ma (MSWD = 1.4), considered as the minimum age of crystalization of the SIN rock.