GRANITOS PÓRFIROS DOS ARREDORES DE SERRA NEGRA, VALINHOS E AMPARO E SUAS RELAÇÕES COM 0 MACIÇO DE MORUNGABA, LESTE DO ESTADO DE SÃO PAULO

EBERHARD WERNICK

Resumo


Results of a comparative quantitative mineralogical volumetric study of plutonic and hypoabissal granitic rocks from the Morungaba Massif, eastern part of the State of São Paulo, Brazil, using the Jung and Brousse petrographic index, are presented. The results show a regular increase of the potash feldspar and quartz content along the sequence of plutonic rocks, hypoabissal porphyritic rocks and aplitic dykes. The colour decreases along the series porphyritic rocks, plutonic rocks and aplitic dykes. The porphyritic rocks are composed by two petrographic phases, each one making up roughly one halfof the rocks. The phase corresponding to phenocrysts of intratelluric origin, exhibits composition near the plutonic rocks, whereas the other phase, i. e., the matrix, shows composition near the aplitic rocks.

Texto completo:

PDF

Apontamentos

  • Não há apontamentos.