A fracture model for quartz ribbons in straight gneisses

MacKinnon, Paula; Fueten, Frank; Robin, Pierre-Yves F.

doi:10.1016/s0191-8141(96)00073-9

Cited by 20 publications

(12 citation statements)

References 29 publications

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“…4d). Quartz-feldspar ribbons reflecting medium to high-grade conditions (Culshaw and Fyson 1984;McLelland 1984;MacKinnon et al 1997;Hippertt et al 2001) are cut by shear bands showing extensive grain size reduction (Fig. 4d), fractures and microfaults.…”

Section: Microstructuresmentioning

confidence: 99%

The Ereendavaa Range (north-eastern Mongolia): an additional argument for Mesozoic extension throughout eastern Asia

Daoudene

Gapais

Ledru

et al. 2009

Int J Earth Sci (Geol Rundsch)

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International audienceMesozoic rift basins locally bounding metamorphic core complexes have been recognized in Transbaikalia and northern China. Numerous basement outcrops located between these two regions, in eastern Mongolia, are considered as pre-Palaeozoic in age. One of these, the Ereendavaa Range, appears as a gneissic core marked by amphibolite-facies metamorphic conditions. The range is overlain to the NW by the unmetamorphosed Mesozoic Onon Basin. Below the basin, the upper part of the range consists of a gently NW-dipping shear zone associated with top-to-the-NW motion. The structural pattern is consistent with syn-extensional exhumation of the range. Preliminary geochronological data indicate that the shear zone is late Jurassic to early Cretaceous in age, coeval with the Onon Basin. These new data from eastern Mongolia constitute a link between Transbaikalia and northern China, indicating that NW-SE extensional Mesozoic tectonics occurred throughout the entire region

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Section: Microstructuresmentioning

confidence: 99%

The Ereendavaa Range (north-eastern Mongolia): an additional argument for Mesozoic extension throughout eastern Asia

Daoudene

Gapais

Ledru

et al. 2009

Int J Earth Sci (Geol Rundsch)

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“…They may have formed during a crack-seal process a high strain rates (Mackinnon et al 1997) especially when they show en echelon alignments. Such textures are common in the orthomylonites KJ18 and KS19 which show type B2 ribbon quartz (Fig.…”

Section: Discussionmentioning

confidence: 99%

Transpression and tectonic exhumation in the Heimefrontfjella, western orogenic front of the East African/Antarctic Orogen, revealed by quartz textures of high strain domains

et al. 2016

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“…A few grains show deformation lamellae or deformation bands, probably due to subsequent deformation. Although there is no strong evidence of intragranular deformation, quartz grains have obvious lattice preferred orientation (LPO), their c axis is parallel to y axis of finite strain, similar to the quartz ribbon fabrics from other high grade region [3,4] . In the gneisses developed quartz ribbon, almost all the quartz grains are concentrated in the quartz ribbons, this suggests that the quartz material was derived from the deformed host rocks.…”

Section: Ribbon Morphologymentioning

confidence: 99%

“…Compositional layering preceded quartz ribbons [1,2] . (2) Diffusion along fractures, suggested by Mackinon et al [3] , based on microstructural features of quartz ribbons. (3) High temperature plastic deformation of quartz grains under granulite facies, characteristic of high temperature mylonite [4][5][6] .…”

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confidence: 99%

“…Studies of their microstructural characteristics, formation mechanism and evolution process may provide deep insight into the tectonic dynamics of high-grade metamorphic rocks in early Precambrian and at deep crustal levels. Therefore, many structural geologists studied microstructural characteristics, environment of formation and mechanism of the polycrystalline quartz ribbons [1][2][3][4][5][6] . But up to now, there is still controversy over the mechanism and formation conditions of quartz ribbons.…”

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confidence: 99%

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Evidence of microstructures and fluid inclusions for the origin of polycrystalline quartz ribbons in high-grade metamorphic rocks in Daqingshan region

Liu

Ke-yong

2007

SCI CHINA SER D

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Polycrystalline quartz ribbons in high-grade metamorphic rocks from the Daqingshan region, are typical microfabrics of, and provide information for, deep crust deformation and metamorphism. The quartz ribbons have straight boundaries and extend stably along gneissosity. They truncate other mineral grains in the rocks and may contain inclusions of such minerals that are lens-shaped and oriented. They frequently end into branching termination. Analysis fluid inclusions in polycrystalline quartz ribbons reveal that the complex types of fluid inclusions are inhomogeneously distributed. They are obviously different from inclusions captured at granulite facies, in both fluid compositions and T-P estimations. Based on microfabric and fluid inclusion analysis, the polycrystalline quartz ribbons are suggested to be formed by SO 2 -rich fluids filling micro-fractures that are parallel to early gneissosity. The SO 2 composition is derived from the deformed host rocks. The fluid phase has significant effects on the rheological characteristics, fracturing of rocks, and formation of quartz ribbons.polycrystalline quartz ribbon, fluid inclusion, microstructure, Daqingshan Polycrystalline quartz ribbons, 0.3-0.6 mm in width, are composed of many oriented rectangle and subrectangle quartz grains, and extend stably with straight boundaries. They are frequently observed in ductile deformation zones in early Precambrian high-grade metamorphic terrains. and form one of the most important fabrics in high-grade metamorphic rocks. Studies of their microstructural characteristics, formation mechanism and evolution process may provide deep insight into the tectonic dynamics of high-grade metamorphic rocks in early Precambrian and at deep crustal levels. Therefore, many structural geologists studied microstructural characteristics, environment of formation and mechanism of the polycrystalline quartz ribbons [1][2][3][4][5][6] . But up to now, there is still controversy over the mechanism and formation conditions of quartz ribbons. Three proposals are: (1) Straight quartz ribbons from deformation of primary compositional layers of quartz or quartz aggregates. Compositional layering preceded quartz ribbons [1,2] . (2) Diffusion along fractures, suggested by Mackinon et al. [3] , based on microstructural features of quartz ribbons. (3) High temperature plastic deformation of quartz grains under granulite facies, characteristic of high temperature mylonite [4][5][6] . The last is the most accepted model. The following evidence is, however, against this model, i.e. the conflict between high energy configuration (stretched shapes) of quartz grains in quartz ribbons and low strain intragranular fabrics, many mineral grains from host rocks occur as inclusions in large quartz ribbons, and some quartz ribbons have branched tails.The polycrystalline quartz ribbons from high-grade metamorphic rocks in the Daqingshan region occur in early Precambrian ductile shear zones. They are struc-

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A fracture model for quartz ribbons in straight gneisses

Cited by 20 publications

References 29 publications

The Ereendavaa Range (north-eastern Mongolia): an additional argument for Mesozoic extension throughout eastern Asia

The Ereendavaa Range (north-eastern Mongolia): an additional argument for Mesozoic extension throughout eastern Asia

Transpression and tectonic exhumation in the Heimefrontfjella, western orogenic front of the East African/Antarctic Orogen, revealed by quartz textures of high strain domains

Evidence of microstructures and fluid inclusions for the origin of polycrystalline quartz ribbons in high-grade metamorphic rocks in Daqingshan region

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