Shear zone vs folding origin for spiral inclusion trails in the Canton Schist

Stallard, Aaron, and Hickey, Ken (2001) Shear zone vs folding origin for spiral inclusion trails in the Canton Schist. Journal of Structural Geology, 23 (12). pp. 1845-1864.

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Abstract

The three-dimensional geometry of spiral inclusion trails from the Canton Schist were measured to determine whether the spirals were a product of porphyroblast rotation within a shear zone, or porphyroblast growth during a series of overprinting fold events. The spiral inclusion trails are composed of three separate, sub-planar inclusion trail surfaces occupying texturally distinct parts of the porphyroblasts. These surfaces are correlated across a >10 km2 area using textural criteria and relative timing. Measured patterns of inclusion trail orientation and asymmetry suggest they did not form by porphyroblast rotation within a non-coaxial shear zone. Rather, the porphyroblasts grew during three successive overprinting fold events (F2–F4), and the spiral inclusion trails represent the accumulated curvature associated with folding of successive axial plane foliations. The data show that spiral garnets are not peculiar to shear zones, and can form by overprinting crenulations and folds. This is consistent with the common occurrence of spiral garnets in multiply-deformed, regionally metamorphosed fold belts.

Item ID: 13280
Item Type: Article (Research - C1)
ISSN: 1873-1201
Keywords: canton schist; folding origin;foliations; porphyroblast rotation; shear zones; spiral inclusion trails
Date Deposited: 04 Dec 2010 12:52
FoR Codes: 04 EARTH SCIENCES > 0403 Geology > 040312 Structural Geology @ 100%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970104 Expanding Knowledge in the Earth Sciences @ 100%
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