Processes of regional metamorphism and ultrametamorphism and some problems of the geology of the deep-lying sections of folded zones |
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| Abstract: | On the basis of 135 pairs of chemical analyses of coexisting hornblendes and biotites, we have established a relationship between the contents of AlIV, AlVI, Fe3+, Mg, Ti, Na, and K and the overall iron index in the hornblendes and the depth of granitoid formation. This relationship has been emphasized by the R-method of factor analysis. We have examined the strength and nature of the correlations between the elements in the hornblendes and have considered the types of Isomorphism in the amphiboles according to depth, from the viewpoint of crystal chemistry. A regular increase in the amounts of AIV in hornblende from <0.8 to > 1.6 formula units; of (AlVI + Fe3+ + Ti) from <0.5 to >1. 0 formula units; of (K + Na) from <0.35 to >0. 64 formula units; and of Group A from <0.24 to >0.51 formula units has been recorded from the near-surface granitoids to the ultra-abyssal types. Biotites In this respect display no adequately clear and reliable information.—Authors. |
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