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MAGMATISMO GRANITÓIDE DAS SUÍTES INTRUSIVAS SANTA CRUZ E ALVORADA NO DOMÍNIO TECTÔNICO CACHOEIRINHA, SW DO CRÁTON AMAZÔNICO

2009; Volume: 23; Issue: 2 Linguagem: Inglês

10.21715/gb.v23i2.308

2358-2812

Larissa Marques Barbosa de Araújo, Antônio Misson Godoy, Amarildo Salina Ruiz, Antenor Zanardo, Jefferson Cassu Manzano, Jeronimo A. Silva,

earthquake and tectonic studies

Santa Cruz and Alvorada granitoids suites are part of the Cachoeirinha Domain situated in the southwest portion of the Amazonian Craton. Santa Cruz batholith striking NNW is constituted by quartz monzodiorite facies and extensive occurrences of biotite monzo- to sienogranites and porphiritic biotite monzogranites. The late stage is represented by the Alvorada plugs, stocks and plutons, constituted by equigranular monzogranites to locally granodiorites and leuco-monzogranites. Four phases of deformation are recognized, the first restricted to the basement rocks, the second is responsible for large shear zones striking NNW, which are associated to the emplacement of the granitic rocks and the last deformation phase defines normal fault striking ENE. The granite rocks show sin- to late-collisio nal characteristics, belonging to the monzogranitic calcium-alkaline medium to high potassium peraluminous to metaluminous series. U-Pb (1561 ± 260 My.) of Santa Cruz porphiritic monzogranite and T DM ages between 1.9 and 2.0 Gy suggest the mantelic fractioning around 2.0 Gy., and point to a hybrid nature of the parental magma, with participation of crustal material. The rocks of Alvorada Suite present ages into the range of 1537 to 1440 My and TDM age of 1.7 to 1.8 My, pointing to fractioning of juvenile mantelic material with the participation of crustal material. Both the suites are genetically associated to the evolution of the Cachoeirinha Magmatic Arc.