A source of heat‐energy in crystallization of granodiorite magma, and some related problems of volcanism

Eos, Transactions, American Geophysical Union
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Abstract

Evidence obtained from thin sections, polished sections, and chemical analyses of granodiorite porphyries from the Ouray District of Colorado show that during crystallization of the granodiorite magma a number of shifts occurred in the equilibrium between the oxides of iron. These changes are reflected in processes of mineralization associated with the magma. The geologic setting of the igneous bodies and episodes of fissuring connected with the mineralization indicate that relief of pressure was the primary cause of the shifts in equilibrium. The iron occurring in the crystallized products and in the residual magmatic liquids is changed from its low to its high state of oxidation and thus provides an internal and potential source of heat‐energy in crystallizing magmas. The transformation of the potential energy into neat is shown to occur both as an episodic process, interrupting the normal course of igneous metamorphism and mineralization near the magma bodies, and also as a more or less continuous process in the production of primary subalkaline magmas. The energy‐transformation is so controlled by crystal fractionation within the magma‐hood that it provides a mechanism by which magma bodies are enabled to rise in the Earth's crust by selective fusion of salic material.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title A source of heat‐energy in crystallization of granodiorite magma, and some related problems of volcanism
Series title Eos, Transactions, American Geophysical Union
DOI 10.1029/TR017i001p00236
Volume 17
Issue 1
Year Published 1936
Language English
Publisher American Geophysical Union
Description 20 p.
First page 236
Last page 255
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