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Percolation threshold and permeability of crystallizing igneous rocks; the importance of textural equilibrium

M. J. Cheadle, M. T. Elliott and D. McKenzie
Percolation threshold and permeability of crystallizing igneous rocks; the importance of textural equilibrium
Geology (Boulder) (September 2004) 32 (9): 757-760

Abstract

The permeability of a crystal mush fundamentally controls the ability of its melt to migrate or segregate with respect to the solid phase and thus controls the extent to which compaction and porous-media convection can occur in crystallizing igneous cumulates. In particular, the existence of a percolation threshold, which defines the porosity at which a crystallizing rock becomes impermeable, can limit the effectiveness of these processes. We present three-dimensional numerical models of the topology of porosity in both texturally equilibrated and nonequilibrated crystal-melt systems; these models enable porosity vs. permeability relationships and hence percolation thresholds to be calculated. The permeability of the nonequilibrated models was calculated using a network-simulation method. These models confirm that there is no percolation threshold for a perfectly texturally equilibrated rock with dihedral angles of <60 degrees . Conversely, the models indicate that the percolation threshold for non-texturally equilibrated rocks is 8%-11%. The models show that permeability is only weakly dependent on the morphology of the crystals at porosities of >20%. These results suggest that the volume of trapped melt in an igneous cumulate may be controlled by the ability of the crystallizing crystal-melt system to reach textural equilibrium.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 32
Serial Issue: 9
Title: Percolation threshold and permeability of crystallizing igneous rocks; the importance of textural equilibrium
Affiliation: University of Wyoming, Department of Geology and Geophysics, Laramie, WY, United States
Pages: 757-760
Published: 200409
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 34
Accession Number: 2004-070962
Categories: Igneous and metamorphic petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus.
Secondary Affiliation: British Petroleum Exploration (Angola), GBR, United KingdomBullard Laboratories, GBR, United Kingdom
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 200421
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