Contrasting rock permeability in the aureole of the Ballachulish igneous complex, Scottish Highlands; the influence of surface energy?

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doi: 10.1007/s004100050380
Authors:Holness, M. B.
Author Affiliations:Primary:
University of Edinburgh, Department of Geology and Geophysics, Edinburgh, United Kingdom
Volume Title:Contributions to Mineralogy and Petrology
Source:Contributions to Mineralogy and Petrology, 131(1), p.86-94. Publisher: Springer International, Heidelberg-New York, International. ISSN: 0010-7999
Publication Date:1998
Note:In English. 50 refs.; illus., incl. sects., 2 tables, sketch maps
Summary:This complex was emplaced at a depth of 10 km into Dalradian metasediments, resulting in melting of the country rocks near the intrusive contact. The greatest extent of melting occurred in the Leven schist in the 400 m wide so-called chaotic zone which experienced infiltration of aqueous fluids from the pluton. In contrast, the feldspar-bearing Appin quartzite underwent significant melting only within a few metres of the intrusion, despite being in contact with the same fluid source. The permeability of the Appin quartzite and quartz horizons in the Leven schist to pervasive grain-edge infiltration of aqueous fluids was determined by measuring the equilibrium quartz-H2O dihedral angle for the P-T conditions of contact metamorphism. Addition of powdered sample of both rock types to the pure quartz-H2O system results in a linear decrease of the quartz-H2O dihedral angle with increasing T, the rate of this increase being greater for the Leven schist than for the Appin quartzite. The results show that quartz-rich horizons in the schist would have been permeable to infiltration of aqueous fluids close to the solidus, permitting extensive H2O-fluxed melting to occur, whereas the quartzite would have remained impermeable to grain-edge flow. [R.A.H.]
Sections:Petrology
Subsections:Metamorphism: thermal, metasomatic
Subjects:Aureoles; Caledonian Orogeny; Contact metamorphism; Dalradian; Experimental studies; Intrusions; Melting; Metamorphic rocks; Metamorphism; Metasedimentary rocks; P-T conditions; Paleozoic; Permeability; Ballachulish Complex; Europe; Great Britain; Scotland; Scottish Highlands; United Kingdom; Western Europe; Appin Quartzite; Leven Schist
Coordinates:N563000 N570000 W0050000 W0060000
Abstract Numbers:98M/4391
Record ID:1999057548
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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