Caracterização petrológica, geoquímica e geocronológica (U/Pb e Ar/Ar) do maciço sararé Nova Lacerda-MT
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Data
2003-10-15
Autores
Ruiz, Larissa Marques Barbosa de Araújo [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
O Maciço Sararé, pertencente ao Terreno Santa Helena no Cráton Amazônico, situa-se a cerca de 60 Km a norte da cidade de Pontes e Lacerda, sudoeste de Mato Grosso, apresentando o contato leste e nordeste recoberto pelas rochas sedimentares da Bacia Cretácica Parecis. Encontra-se intrusivo em rochas metamórficas do Complexo Vulcano-sedimentar Pontes e Lacerda em gnaisses e migmatitos ortoderivados (Complexo Metamórfico Alto Guaporé, Maciço Sapé e Anhanguera) de idades mesoproterozóicas. Compreende um corpo de 80 Km2, constituído por três fácies petrográficas graníticas principais, cujos contatos são transicionais. As rochas apresentam composição monzogranítica, são inequigranulares a localmente porfiríticas, granulação dominantemente média, constituídas por microclínio, quartzo, oligoclásio límpido ou saussuritizado , abundantes placas de muscovita (primárias ou secundárias), rara biotita cloritizada e fluorita metassomática, além de titanita e minerais opacos. A Fácies Biotita Monzogranito é dada por rochas equigranulares de granulação média-fina, cor avermelhada, leucocráticas, isotrópicas que ocorrem na porção sul do corpo. A Fácies Muscovita Monzogranito é representada por rochas inequigranulares, granulação média-grossa, cor rósea, hololeucocráticas e isotrópicas, que ocorrem na porção norte e central da intrusão. A ocorrência principal da Fácies Monzogranito aflora no extremo norte da área de forma isolada, como um plug granítico e dentro do maciço como diques aplíticos tardios. São constituídas por rochas leucocráticas, róseas, isotrópicas, ineqüigranulares a porfiríticas de granulação fina a média. A tectônica regional com direção NW-SE controla e define a forma alongada do Maciço Sararé acompanhando o trend regional de suas encaixantes. Tardiamente, uma tectônica rúptil manifestada através de fraturas...
The Sararé Granite belongs to the Santa Helena Terrain within the Amazonian Craton and is located about 60 km north of the city of Pontes and Lacerda, of southwest Mato Grosso. The east and northeast contacts of the body are marked by the sedimentary rocks of the Cretaceous Parecis Basin, while its remaining intrusive contacts are the metamorphic rocks of the Pontes and Lacerda volcano-sedimentary complex and orthogneisses and migmatites (Alto Guaporé Metamorphic Complex, Sapé and Anhangüera Massifs) of Mesoproterozoic age. The areal extent of the instrusion is approximately 80 km2 and is constituted by three major monzogranitic petrographic facies (biotite monzogranite, muscovite monzogranite and monzogranite) whose contacts are transitional. These rocks present monzogranitic composition, are unequigranular to locally porphyritic with medium grain size, constituted by microcline, quartz, oligoclase, abundant muscovite, rare cloritized biotite and metassomatic fluorite plus titanite and opaque minerals. Biotite monzogranitic facies is represented by equigranular of medium to small grain size, red-colored, leucocratic and isotropic rocks, that crop out in the southern portion of the body. The facies of muscovite monzogranite is represented by medium to coarse inequigranular textures, rose-colored, hololeucocratic and isotropic rocks that occur in the north and central portion of the intrusion. Monzogranite facies crops out in its main occurrence in the north end of the area and are interpreted as late-stage granitic plugs, constituted by inequigranular of medium to small grain size to porphyritic leucocratic rosy isotropic rocks. Their occurrence is characterized as localized intrusive bodies, including late aplite dikes, into the other ...(Complete abstract click electronic access below)
The Sararé Granite belongs to the Santa Helena Terrain within the Amazonian Craton and is located about 60 km north of the city of Pontes and Lacerda, of southwest Mato Grosso. The east and northeast contacts of the body are marked by the sedimentary rocks of the Cretaceous Parecis Basin, while its remaining intrusive contacts are the metamorphic rocks of the Pontes and Lacerda volcano-sedimentary complex and orthogneisses and migmatites (Alto Guaporé Metamorphic Complex, Sapé and Anhangüera Massifs) of Mesoproterozoic age. The areal extent of the instrusion is approximately 80 km2 and is constituted by three major monzogranitic petrographic facies (biotite monzogranite, muscovite monzogranite and monzogranite) whose contacts are transitional. These rocks present monzogranitic composition, are unequigranular to locally porphyritic with medium grain size, constituted by microcline, quartz, oligoclase, abundant muscovite, rare cloritized biotite and metassomatic fluorite plus titanite and opaque minerals. Biotite monzogranitic facies is represented by equigranular of medium to small grain size, red-colored, leucocratic and isotropic rocks, that crop out in the southern portion of the body. The facies of muscovite monzogranite is represented by medium to coarse inequigranular textures, rose-colored, hololeucocratic and isotropic rocks that occur in the north and central portion of the intrusion. Monzogranite facies crops out in its main occurrence in the north end of the area and are interpreted as late-stage granitic plugs, constituted by inequigranular of medium to small grain size to porphyritic leucocratic rosy isotropic rocks. Their occurrence is characterized as localized intrusive bodies, including late aplite dikes, into the other ...(Complete abstract click electronic access below)
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Petrologia - Mato Grosso, Petrography, Geochemistry
Como citar
RUIZ, Larissa Marques Barbosa de Araújo. Caracterização petrológica, geoquímica e geocronológica (U/Pb e Ar/Ar) do maciço sararé Nova Lacerda-MT. 2003. x, 89 f. Dissertação (mestrado) - Universidade Estadual Paulista, Instituto de Geociências e Ciências Exatas, 2003.