Melting and melt segregation in the aureole of the Glenmore Plug, Ardnamurchan

Holness, M. B. and Dane, K. and Sides, R. and Richardson, C. and Caddick, M. (2005) Melting and melt segregation in the aureole of the Glenmore Plug, Ardnamurchan. Journal of Metamorphic Geology, 23 (1). pp. 29-43. DOI 10.1111/j.1525-1314.2005.00560.x

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Abstract

Contact metamorphism caused by the Glenmore plug in Ardnamurchan, a magma conduit active for 1 month, resulted in partial melting, with melt now preserved as glass. The pristine nature of much of the aureole provides a natural laboratory in which to investigate the distribution of melt. A simple thermal model, based on the first appearance of melt on quartz–feldspar grain boundaries, the first appearance of quartz paramorphs after tridymite and a plausible magma intrusion temperature, provides a time-scale for melting. The onset of melting on quartz–feldspar grain boundaries was initially rapid, with an almost constant further increase in melt rim thickness at an average rate of 0.5–1.0 × 10−9 cm s−1. This rate was most probably controlled by the distribution of limited amounts of H2O on the grain boundaries and in the melt rims. The melt in the inner parts of the aureole formed an interconnected grain-boundary scale network, and there is evidence for only limited melt movement and segregation. Layer-parallel segregations and cross-cutting veins occur within 0.6 m of the contact, where the melt volume exceeded 40%. The coincidence of the first appearance of these signs of the segregation of melt in parts of the aureole that attained the temperature at which melting in the Qtz–Ab–Or system could occur, suggests that internally generated overpressure consequent to fluid-absent melting was instrumental in the onset of melt movement.

Item Type: Article
Uncontrolled Keywords: 2005 PUBL 2005 AREP IA46 BPI IA47
Subjects: 05 - Petrology - Igneous, Metamorphic and Volcanic Studies
Divisions: 05 - Petrology - Igneous, Metamorphic and Volcanic Studies
Journal or Publication Title: Journal of Metamorphic Geology
Volume: 23
Page Range: pp. 29-43
Identification Number: 10.1111/j.1525-1314.2005.00560.x
Depositing User: Sarah Humbert
Date Deposited: 21 Mar 2011 11:46
Last Modified: 23 Jul 2013 09:58
URI: http://eprints.esc.cam.ac.uk/id/eprint/1689

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