Vorticity analysis and recognition of ductile extension in the Sanbagawa Belt, SW Japan

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doi: 10.1016/0191-8141(95)00005-X
Authors:Wallis, Simon
Author Affiliations:Primary:
Kyoto University, Department of Geology and Mineralogy, Kyoto, Japan
Volume Title:Journal of Structural Geology
Source:Journal of Structural Geology, 17(8), p.1077-1093. Publisher: Pergamon, Oxford-New York, International. ISSN: 0191-8141
Publication Date:1995
Note:In English. 84 refs.; illus., incl. 2 plates, geol. sketch map
Summary:Metamorphic belts in the internal parts of mountain belts have invariably undergone regional penetrative deformation. Such deformation may form as a result of bulk simple shear between two essentially rigid plates or, alternatively, as a result of ductile thickening or thinning; studies of the degree of non-coaxiality during deformation (vorticity analyses) can help to distinguish between the resulting kinematic histories. Possible indicators of the degree of non-coaxiality include : 1) the rotation of porphyroclasts with different aspect ratio, 2) the distribution of sets of material lines with different stretch histories, 3) geometries of crystallographic fabrics and 4) the orientation of oblique grain shape fabrics. Application of such methods to the Sanbagawa metamorphic belt suggests that the dominant regional tectonic fabric, associated with orogen-parallel shearing, formed as a result of ductile extension; quantitative analyses suggest that the associated thinning was of the order of 50 %. [R.A.H.]
Subjects:Cretaceous; Deformation; Detection; Ductile deformation; Extension tectonics; Foliation; Framework silicates; Izumi Group; Kinematics; Lineation; Mesozoic; Metamorphic belts; Metamorphic rocks; Paleozoic; Petrofabrics; Petrography; Preferred orientation; Quartz; Schists; Senonian; Shear; Silica minerals; Silicates; Structural analysis; Tectonics; Upper Cretaceous; Zoning; Asia; Chichibu Belt; Far East; Honshu; Japan; Kurosegawa Zone; Kyushu; Median Tectonic Line; Mino Belt; Ryoke Belt; Sambagawa Belt; Shikoku; Shimanto Belt; Sanbosan Belt; Vorticity analysis
Abstract Numbers:96M/1213
Record ID:1995070539
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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