Some time–space relationships for crustal melting and granitic intrusion at various depths
Published:January 01, 1999
Alan Bruce Thompson, 1999. "Some time–space relationships for crustal melting and granitic intrusion at various depths", Understanding Granites: Integrating New and Classical Techniques, Antonio Castro, Carlos Fernández, Jean Louis Vigneresse
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Crustal melting occurs at the higher grades of metamorphism. Migmatites reflect crustal anatexis without necessary additional heat supply. Granites usually result from crustal melting resulting from ‘hot’ geotherms, or reflect an external heat supply.
The commonest mechanisms of crustal melting are: (i) decompression of crust thickened into mantle in convergent orogens; (ii) asthenosphere upwelled beneth the crust in extensional orogens; (iii) massive invasion or underplating of crust by mantle magma generated by mantle decompression. This paper considers some of the processes governing timescales and lengthscales of these various magmatic events with particular view to determining the intensity and duration of crustal melting, and relationships between the rates of melt extraction, ascent and emplacement.
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Understanding Granites: Integrating New and Classical Techniques
Granite magmatism represents a major contribution to crustal growth and recycling and, consequently, is one of the most important mechanisms to have contributed to the geochemical differentiation of the Earth’s crust since Archaean time. Granites are also often associated with ore bodies, and their study therefore has direct commercial relevance.
The modern view of the granite problems requires the application of many different theoretical, experimental and empirical resources provided by geophysics, geochemistry, experimental petrology, structural geology, scale modelling and field geology. Because of the complexity of the granite problem, it is necessary to integrate a variety of techniques and corroborate the findings with field observations.This is the philosophy of this book.
Many chapters are review papers dealing with the development and achievements of a particular technique, whilst other chapters deal with the application of a number of techniques to a specific problem. This volume brings together papers that would otherwise be dispersed in different publications.
The book will be of interest to igneous petrologists, geophysicists, structural geologists and geochemists.