Die r�ntgenographische und optische Gef�geanalyse von Erzen, insbesondere mit dem Z�hlrohr-Texturgoniometer

Gehlen, Kurt v.

doi:10.1007/bf01142193

Cited by 22 publications

(8 citation statements)

References 35 publications

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“…Chromitite is generally too coarse grained to allow a sufficient number of grains to be found within the analyzed 2 x 2 cm area in order to obtain reproducible patterns. This has already been shown by GEHLEN (1960), who analyzed only two grains in a chromitite from Turkey. The very strong peaks on the different diffractograms, often with a change from maximum to minimum value with 5 ~ distance, suggest that the large chromite grains are perfect without bending of the lattice or internal substructures (e.g.…”

Section: Crystallographic Orientation Of Chromitesupporting

confidence: 51%

Deformation fabric and microstructures in ophiolitic chromitites and host ultramafics, Sultanate of Oman

Christiansen

1985

Geol Rundsch

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f-larzburgite and dunite from the Oman ophiolite display a strong olivine fabric and microstructures typical for high temperature mantle deformation. The syntectonic, magmatically formed, chromitites occurring throughout the mantle sequence vary from almost undeformed (resembling chromitite from stratiform complexes) to highly deformed. Usually the interstitial silicates in the deformed ore possess a fabric similar to those of the host rocks, whereas a weak or poikilitic fabric is observed on relatively undeformed deposits. Chromite grains are elongated and flattened, defining strong foliations and lineations, in disseminated ore, and pull-apart-like structures perpendicular to the lineation form in the coarser massive ore. No preferred crystallographic orientation of chromite has been detected with the Xray-texture goniometer, and it is proposed that chromite mainly deforms by passive rotation in the weaker silicate matrix, cataclasis and diffusion creep. crostructures typiques de d6formations mantelliques de haute temp&ature. Les chromitites, d'origine magmatique syntectonique, qui se trouvent le long de la s6quence mantellique varient entre des termes presque non d4form& (ressemblant aux chromitites des complexes stratiformes) jusqu'~. des termes tr6s d6form6s. Les silicates interstitiels du mineral d6form6 pr&entent fr4quemment une fabrique semblable ~t celle des min&aux de ia roche h6te alors que l'on observe une fabrique peu d&elopp& ou bien une texture poecilitique dans ies minerals des gisements relativement peu d&form&. Les cristaux de chromite sont allong4s et aplatis, d6finissant une foliation et une iin6ation tr6s marqu&s dans ies minerals diss6min&; des structures d'&i-rement (pull-apart) perpendiculaires ~ la lin6ation apparaissent dans les minerals plus massifs. Aucune orientation cristallographique pr4ferentielle n'a pu &re mise en &idence au goniom&re de texture; on propose donc que la chromite se d~forme principalement par rotation passive dans une matrice silicat& plus fragile, par cataclase et par fluage-diffusion.

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Section: Crystallographic Orientation Of Chromitesupporting

confidence: 51%

Deformation fabric and microstructures in ophiolitic chromitites and host ultramafics, Sultanate of Oman

Christiansen

1985

Geol Rundsch

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“…The hematite ores, from which pole figures are described here, were formed under different conditions of regional metamorphism without significant post-deformational heating which would give rise to a pronounced recrystallization and weak grain anisotropy, as described from central Sweden (von Gehlen, 1960;Wagner et al, 1977). Deformation twins are rarely developed.…”

Section: Procedures Of Texture Analysis and Simulationmentioning

confidence: 99%

“…Textures of naturally deformed hematite ores were initially described from individual samples of various locations (Neff and Paulitsch, 1960;von Gehlen, 1960;Ambs, 1966). More systematic investigations concerned recrystallized banded ores from Precambrian deposits of central Sweden and North America (HennigMichaeli, 1976(HennigMichaeli, , 1977aWagner et al, 1977).…”

Section: Introductionmentioning

confidence: 99%

Natural and Simulated (10.4) Pole Figures of Polycrystalline Hematite

Quade¹

1988

Texture, Stress, and Microstructure

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“…Sulphide textures may be measured using either optical (Ko~N 1988, SCHACH-NER-KoRN 1948, LAXaSON 1978 or X-ray techniques (von GEHLEN 1960, SIEMES 1977. SANDEn (1980) discusses the determination of fabrics using film techniques.…”

Section: Texture Measurement In Sulphidesmentioning

confidence: 99%

“…Since then systematic studies of preferred orientations in both naturally and experimentally deformed ore minerals have largely been carried out by S~EMES (1970S~EMES ( , 1977 and his co-workers (BA'fER and SIEMES 1971, LANG 1968, SAYmSCH 1970, HENNIG-MIcHELI 1977. Other studies of the textures in ore minerals include von GEHLEN (1960), LARSON (1978), YPMA (1975) and McCLAY (1978McCLAY ( , 1980. This paper briefly reviews the methods and problems of texture determinations in sulphides: the deformation mechanisms in sulphide minerals and the development of textures: selected examples of textures in deformed sulphide ores, and finally a brief discussion on computer simulations of sulphide textures (carried out by Gordon Lister).…”

Section: Introductionmentioning

confidence: 97%

Fabrics of deformed sulphides

McClay

1983

Geol Rundsch

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Zusammenfassung Abstrae,tDetermination of preferred orientations in sulphide ores is an important facet in the analysis of the deformation and metamorphism in ore deposits. The methodology and problems of texture determinations in deformed sulphides are briefly reviewed. Deformation mechanisms and texture development in the common sulphide minerals are summarised. Axi-symmetrie experimental deformation of galena, sphalerite and chaleopyrite produces similar pole figures with the (110) planes aligned normal to the compression axis. Deformation textures in naturally deformed sulphides however are best preserved in monomineralie ores which have undergone simple shear deformation. These textures can be correlated with the microstruetures found in the sulphides. Computer simulations of deformation textures arising from dislocation mechanisms can be used to interpret the textures but the results to date are preliminary. These theoretical models emphasize the importance of the symmetry of the kinematic axes of the deformation, the operative glide systems and the strain history and the deformation path. Little is known, however, of the influence of static and dynamic reerystallisation on sulphide preferred orientations. R6sum6La d6termination des orientations pr6f6rentielles dans les minerals sulfur6s est un c6t6 important dans l'analyse de la d6formation et du m6tamorphisme dans les gltes m6tal-lif4res. La m6thodologie et les probl6mes des d6formations texturales dans les sulfures

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Die r�ntgenographische und optische Gef�geanalyse von Erzen, insbesondere mit dem Z�hlrohr-Texturgoniometer

Cited by 22 publications

References 35 publications

Deformation fabric and microstructures in ophiolitic chromitites and host ultramafics, Sultanate of Oman

Deformation fabric and microstructures in ophiolitic chromitites and host ultramafics, Sultanate of Oman

Natural and Simulated (10.4) Pole Figures of Polycrystalline Hematite

Fabrics of deformed sulphides

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