Deformation and displacement in complex mylonite zones
A complex mylonite zone contains rock types of varied mineralogy and a range in mylonitic textures, depending on rock type and strain history. The field structural geologists working in a complex mylonite zone is interested in (1) internal deformation in the zone and (2) regional displacement (tectonic transport) predicted by structures within the zone. It is common to determine a principal elongation direction or to determine a general shear sense from one or more of the numerous small-scale criteria available. Of interest here are the relationships among stretched grains, shear sense, regional displacement, and shear bands in button schist. Potential elongations between shear bands in button schist from the Brevard zones in North Carolina include: (1) chlorite tails on retrograded garnets, (2) pulled-apart grains, particularly epidote, garnet, pyrite, and rare feldspar, and (3) linear aggregates of quartz grains. Stereonet orientations of these lineations are dispersed along the average great circle for mylonite foliation orientation because of crenulations associated wit the shear bands but, in general, the lineations are concentrated near the strike of the foliation. In this case, finite elongations and shear sense criteria agree in giving a regional strike-slip style of tectonic transport and the local shear direction is contained in a plane normal to both the mylonite foliation and the shear bands. The shear direction thus determined is a simple shear component of th actual particle displacement in the shear zone because a component of pure shear may be involved in the formation of shear bands.
- Research Organization:
- Univ. of North Carolina, Charlotte (USA)
- OSTI ID:
- 6593440
- Report Number(s):
- CONF-8510489-
- Journal Information:
- Geol. Soc. Am., Abstr. Programs; (United States), Journal Name: Geol. Soc. Am., Abstr. Programs; (United States) Vol. 17; ISSN GAAPB
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
580300* -- Mineralogy
Petrology
& Rock Mechanics-- (-1989)
580400 -- Geochemistry-- (-1989)
CHALCOGENIDES
CHLORITE MINERALS
FEDERAL REGION IV
FELDSPARS
GARNETS
GEOLOGIC HISTORY
IRON COMPOUNDS
IRON SULFIDES
LITHOLOGY
MECHANICAL PROPERTIES
MECHANICS
METAMORPHIC ROCKS
MINERALOGY
MINERALS
NORTH AMERICA
NORTH CAROLINA
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PYRITE
QUARTZ
ROCK MECHANICS
ROCKS
SCHISTS
SHEAR
SHEAR PROPERTIES
SILICATE MINERALS
SILICATES
SILICON COMPOUNDS
SILICON OXIDES
STRAINS
STRESS ANALYSIS
SULFIDE MINERALS
SULFIDES
SULFUR COMPOUNDS
TECTONICS
TRANSITION ELEMENT COMPOUNDS
USA