Einführung in die Gefügekunde der Geologischen Körper

Sander, Bruno

doi:10.1007/978-3-7091-3636-2

Cited by 49 publications

(20 citation statements)

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“…Details on these techniques can be found in the Appendix A. While X-ray diffraction allows a volume-related, quantitative texture analysis, the CIP-method gives instead a grain-or microstructural domain-related determination of the c-axis directions, which can be visualized by an "Achsenverteilungsanalyse" (AVA, axis distribution analysis) [e.g., Sander, 1950;Trommsdorf and Wenk, 1963]. The thin sections used for the CIP analysis (and for the microstructural analysis) were prepared from mirror sample chips of those used for the X-ray analysis.…”

Section: Methodsmentioning

confidence: 99%

Development of crystallographic preferred orientation and microstructure during plastic deformation of natural coarse‐grained quartz veins

Pennacchioni

Menegon

Leiss³

et al. 2010

J. Geophys. Res.

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[1] The microstructure and crystallographic preferred orientation (CPO) of quartz were quantified in 17 samples of natural monomineralic tabular veins. The veins opened and were deformed, up to shear strain g > 15, in a small temperature window (about 25°C) above 500°C, as established by Ti-in-quartz thermometry. The veins filled a set of fractures within the Adamello tonalite (southern Alps, Italy) and localized homogeneous simple shear during postmagmatic cooling. The local (square millimeter scale) and bulk (square centimeter) CPO were investigated by computer-integrated polarization microscopy (CIP) and X-ray texture goniometry. Weakly deformed veins (WDV: g < 1) consist of millimeter-to centimeter-sized crystals with a strong CPO showing a c-axis girdle slightly inclined, mostly with the shear sense, to the foliation (XY) plane and a strong maximum close to the lineation (X). Moderately deformed veins (MDV: 2 < g < 3) consist of elongated nonrecrystallized ribbon grains and most have a CPO showing a strong Y maximum of c axes some with weak extension into a YZ girdle. Strongly deformed veins (SDV: g = 4 to 15) are pervasively to completely recrystallized to fine (34-40 mm grain size) aggregates with a strong CPO similar to that of MDV. The slip systems during plastic deformation were dominantly prism hai with subordinate rhomb and basal hai slip. Recrystallization occurred rather abruptly for 3 < g < 4. In contrast to dislocation creep experiments in quartz (and other minerals), a steady-state recrystallized fabric is achieved at early stages of deformation (g ≈ 4) as there is no evidence, with increasing strain, of strengthening of the CPO, of rotation of the fabric skeleton, or of change in grain size. WDV represent weakly deformed relicts of veins with an initial CPO believed to have developed during crystal growth but unsuitably oriented for prism hai slip during subsequent shear. MDV and SDV appear to derive from veins different from WDV, where the vein crystals grew with orientation favorable for prism hai slip. The relationship between the initial growth CPO and the kinematic framework suggests that veins opened at a temperature close to that at which there is a switch between the activity of prism hci and prism hai slip, with the temperature of growth causing growth of crystals well oriented for slip. The initial CPO of veins, from which quartz mylonites are commonly derived, plays a critical role in the fabric evolution. The strong growth-and strain-induced CPOs of these sheared veins inhibited significant reworking during lower temperature stages of pluton cooling when basal hai slip would have been dominant.

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Section: Methodsmentioning

confidence: 99%

Development of crystallographic preferred orientation and microstructure during plastic deformation of natural coarse‐grained quartz veins

Pennacchioni

Menegon

Leiss³

et al. 2010

J. Geophys. Res.

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“…2 and 3, these six orientational domains are presented by various diagonally hatched patterns and shades of gray. Note that this technique is really just a generalized form of the AVA method (Achsenverteilungsanalyse) previously described by Ramsauer (1941) and Sander (1950).…”

Section: Experimental Configuration and Conditionsmentioning

confidence: 99%

The evolution of high-temperature mylonitic microfabrics: evidence from simple shearing of a quartz analogue (norcamphor)

Herwegh

Handy

1996

Journal of Structural Geology

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Abstract-Plane strain simple shearing of norcamphor (C,HiuO) in a see-through deformation rig to a shear strain of y = 10.5 at a homologous temperature of Ts = 0.81 yields a microfabric similar to that of quartz in amphibolite facies mylonite. Synkinematic analysis of the norcamphor microfabric reveals that the development of a steady-state texture is linked to changes in the relative activities of several grain-scale mechanisms. Three stages of textural and microstructural evolution are distinguished: (1) rotation and shearing of the intracrystalline glide planes are accommodated by localized deformation along three sets of anastomozing microshears. A symmetrical c-axis girdle reflects localized pure shear extension along the main microshear set (S,) oblique to the bulk shear zone boundary (abbreviated as SZB); (2) progressive rotation of the microshears into parallelism with the SZB increases the component of simple shear on the S, microshears. Grain-boundary migration recrystallization favours the survival of grains with slip systems oriented for easy glide. This is associated with a textural transition towards two stable c-axis point maxima whose skeletal outline is oblique with respect to the S, microshears and the SZB; and (3) at high shear strains (y > 8), the microstructure, texture and mechanism assemblage are strain invariant, but strain continues to partition into rotating sets of microshears. Steady state is therefore a dynamic, heterogeneous condition involving the cyclic nucleation, growth and consumption of grains.

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“…The OD resolution of both methods will be similar for an equivalent amount of experimental texture information (Helming et al, 1994). The c-axes form a crossed girdle as is typical of quartzites deformed at relatively low metamorphic grade (Sander, 1950 The arrangement ofthe detector banks at different 20 positions in the present experiment requires some non-trivial corrections. Different detectors see the same diffraction peak at different neutron wavelengths A.…”

Section: Introductionmentioning

confidence: 93%

Texture Analysis of Quartzite by Whole Pattern Deconvolution

Matthies

Lutterotti

Ullemeyer

et al. 1999

Texture, Stress, and Microstructure

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The recently developed RITA concept combines algorithms of the Rietveld structure analysis with those from modern texture analysis in order to get texture information from d-spacing diffraction spectra. It is demonstrated for a low symmetry material (quartz) and a minimum pole sphere covering by the measured spectra. The quality of the results underlines the efficiency of this new approach especially for time-of-flight neutron diffraction studies where access to the beam is limited. New interesting aspects for crystal structure refinement are discussed.

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Einführung in die Gefügekunde der Geologischen Körper

Cited by 49 publications

References 0 publications

Development of crystallographic preferred orientation and microstructure during plastic deformation of natural coarse‐grained quartz veins

Development of crystallographic preferred orientation and microstructure during plastic deformation of natural coarse‐grained quartz veins

The evolution of high-temperature mylonitic microfabrics: evidence from simple shearing of a quartz analogue (norcamphor)

Texture Analysis of Quartzite by Whole Pattern Deconvolution

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