Modelling of the Relations Between Reaction Enthalpy and the Buffering of Reaction Progress in Metamorphism

John Ridley
Institut für Mineralogie und Petrographie, ETH-Zentrum, CH-8092, Zürich, Switzerland*
*Present address: Department of Geology, University of Zimbabwe, PO Box MP 167, Mount Pleasant, Harare, Zimbabwe.

Abstract: A proportion of the heat added to a body of rock during prograde metamorphism will be absorbed in the chemical work of metamorphic recrystallization. When and where heat is so absorbed will affect the exact thermal histories of the rocks, and hence the metamorphic textures. This paper reports the results of modelling of the inter-relations between reaction progress and thermal histories in a rock column. The results suggest that volumes of rock undergoing reaction at any moment act as heat sinks and absorb heat from the surrounding rock, that reaction generally takes place close to the temperature at which nucleation took place, and that steady heating of a rock pile can give rise to a reaction history in which spurts of reaction are separated by ‘quiet’, non-reactive intervals.

Keywords: prograde metamorphism • kinetics • heat flow • reaction enthalpy

Mineralogical Magazine; September 1986 v. 50; no. 357; p. 375-384; DOI: 10.1180/minmag.1986.050.357.03
© 1986, The Mineralogical Society
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