Simple shear deformation and quartz crystallographic fabrics; a possible natural example from the Torridon area of NW Scotland

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doi: 10.1016/0191-8141(90)90046-2
Authors:Law, R. D.; Schmid, S. M.; Wheeler, J.
Author Affiliations:Primary:
Va. Polytech. Inst. and State Univ., Dep. Geol. Sci., Blacksburg, VA, United States
Eidg. Tech. Hochsch., Switzerland
Univ. Liverpool, United Kingdom
Volume Title:Journal of Structural Geology
Source:Journal of Structural Geology, 12(1), p.29-45. Publisher: Pergamon, Oxford-New York, International. ISSN: 0191-8141
Publication Date:1990
Note:In English. 42 refs.; illus. incl. 2 plates
Summary:The microstructures and crystallographic fabrics of a 30 cm wide deformed quartz vein are described. In thin section the vein is a mylonite composed of dynamically recrystallized, elongate quartz grains aligned oblique to the mylonitic foliation. The a-axis fabric consists of a dominant single point maximum, orientated within the XZ plane at 9 degrees to the lineation (X); this point maximum occupies a pole position in the corresponding single girdle c-axis fabric. For individual positions on the c-axis fabric skeleton, the orientations of potential crystallographic slip systems (slip plane and direction) relative to shear zone co- ordinates were calculated by orientation distribution function analysis. The calculation of relative resolved shear stresses (Schmid factors) for the potential slip systems, assuming a simple shear kinematic framework, reveals an elegantly simple relationship between individual grain c-axis orientation and corresponding orientations of potential slip systems. [J.M.H.]
Subjects:Crystal structure; Deformation; Field studies; Foliation; Framework silicates; Goniometry; Metamorphic rocks; Mylonites; Petrofabrics; Preferred orientation; Quartz; Shear; Shear zones; Silica minerals; Silicates; Structural analysis; Structural geology; X-ray data; Europe; Great Britain; Scotland; United Kingdom; Western Europe; Northwestern Scotland; Schmid factor analysis; Torridon
Abstract Numbers:90M/4625
Record ID:1990029598
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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