Geologia do embasamento do domínio Uaupés, Província Rio Negro, Cráton Amazônico

Abstract

The goal of this study was petrographic, structural and geochemistry characterization of the Querari Complex, into Uaupés Domain, Rio Negro Province. The studied area is located of the extreme NW of the Amazonas state, Brazil. Integrating field, petrographic and whole rock geochemistry, data it was possible to identified two different facies, Matupi and Panã-Panã. The last have a syeno to monzogranite composition, with a course to porphyritic texture, with titanite, epidote, allanite. Are calcio-alkaline, metaluminous, exhibit incompatible trend for MgO, Fe2O3(t) and TiO2, and compatible trend for Al2O3 e Na2O. For the trace elements, it was observed a fractional pattern for the LREE, for the ratio (La/Yb)N = 21.48-5.42, (La/Sm)N = 6.34-3.48) ((Gd/Yb)N = 1.63-1.06 and negative anomalies of the Ba, Sr and Eu, (Eu(n)/Eu* = 0.45-0.21 a), in spidergrams. The Matupi facies, has syenogranitic composition, with coarse to porphyritic texture, with two micas and epidote. They are alkaline rocks, peraluminous, with incompatible trend for Al2O3, Rb and Sr, and compatible trend for MgO, CaO and TiO. In spidergrams, there is variation in the REE fractionation, the two more enriched samples show more fractional pattern (La/Yb)N = 12.16-10.87 and, while others show a flat fractional pattern more horizontalized (La/Yb)N 3.25-1.56. However, don’t have significant variation in the negative anomaly of Eu (Eu(n)/Eu* = 0.37-0.15). Both facies show the same structural pattern, with foliation S1 // S0 with directions NE-SW, foliation S2 with direction E-W and foliation S3 parallel to S1. The metamorphic event M1 in the Staterian was responsible for the merge of the Querari magmas in continental magmatic arc environment. The syntectonic cooling of these magmas generated the foliation S1 // S0.The Metamorphic event M2, who is associated with the accommodation of type I and S granites in the Rio Negro Province during Calymmian, generated in both Panã-Panã and Matupi facies, the foliation S2 with tendency E-W, having caused in the light crenulation in foliation S1. The deformation textures in the solid state, associated with the generation in the Panã-Panã facies of mineral paragenesis formed by titanite, epidote, magnetite and oligoclase (An> 17%) that allowed to conclude, have reached this event amphibolite facies, of 700 ° C. The M3 metamorphic associated at ductile shear zones with sinistral kinematics, generated in both the Facies S3//S1 foliation and deformation textures in the solid state, and also in the Panã-Panã facies, mineral paragenesis formed by titanite, biotite, magnetite and plagioclase (An> 17%). In the metamorphic event M3 the temperature increased enough to begin the process of anatexia. This event is related at intracratonic reflection of the Grenviliana-Sunsás continental collision, event K'Mudku (1317 to 1198 Ma). The comparison of the rocks of the Cauaburi and Querari Complexes indicates different sources and / or different evolutionary processes. However, the structural and metamorphic data suggest a similar evolution. It is proposed that the rocks of the Cauaburi and Querari Complexes were formed in a continental magmatic arc (1.81 to 1.74 Ga) with the fusion of distinct sources at different times.