The computer contouring of fabric diagrams

The degree of preferred orientation of hornblende in two boudinage structures is analyzed by means of an X-ray texture goniometer. Relative values of reflected intensity for {110} are plotted on the stereographic net, and contoured at convenient intervals. As in conventional fabric diagrams for hornblende, {110} define a great-circle girdle whose breadth reveals the density of unimodal grouping of [001].The density of grouping of [001] varies throughout both boudinage structures. It decreases with increasing extension in structure A, and seems to have a similar trend in structure B, where the determined variation in degree of grain alignment is of doubtful statistical significance.The inverse relationship between the degree of preferred orientation and the magnitude of extension may be attributed to rotation of the principal directions of finite strain during syntectonic crystallization. Alternatively, reorientation of strained grains by annealing recrystallization may have produced the inverse trend.

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On Tests of Significance of Preferred Orientation in Three-Dimensional Fabric Diagrams

The Journal of Geology ◽

10.1086/626533 ◽

1958 ◽

Vol 66 (5) ◽

pp. 526-539 ◽

Cited By ~ 24

Author(s):

Derek Flinn

Keyword(s):

Three Dimensional ◽

Preferred Orientation ◽

Tests Of Significance ◽

Fabric Diagrams

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Least-squares Analysis of Fabric Data: A Note on Conical, Cylindroidal and Near–cylindroidal Folds

Canadian Journal of Earth Sciences ◽

10.1139/e71-066 ◽

1971 ◽

Vol 8 (6) ◽

pp. 694-697 ◽

Cited By ~ 5

Author(s):

C. S. Venkitasubramanyan

Keyword(s):

Least Squares ◽

Stereographic Projection ◽

Rotation Axis ◽

Computational Procedure ◽

Apical Angle ◽

Small Circle ◽

Best Fitting ◽

Fabric Diagrams ◽

The Mean

A cylinder and a plane may be considered as special limiting cases for a right circular cone as the semi-apical angle approaches 0° and 90° respectively (Loudon 1964, Kelley 1966). If these forms are viewed as surfaces generated by an array of lines in space, the rotation axis for the array (the axis of the "cone") can be determined from the orientations of the surface-generating lines by a single computational procedure, using least-squares criterion. The mean angle between the rotation axis and the surface-generating lines will be the semi-apical angle of the cone. However, if this method for determination of the semi-apical angle of the cone, and therefore the best-fitting small circle, is extended to fabric diagrams, in which an array of lines may only statistically describe a great circle or small circle on a stereographic projection, ambiguities arise in certain cases and the semi-apical angle obtained may not be the true semi-apical angle. The difficulty arises because the poles to foliation surfaces are arbitrarily assigned "senses".

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Crystal shape in polar glaciers and the philosophy of ice-fabric diagrams

Journal of Glaciology ◽

10.3189/s002214300003135x ◽

1969 ◽

Vol 8 (53) ◽

pp. 324-326 ◽

Cited By ~ 1

Author(s):

Roger LeB. Hooke

Keyword(s):

Crystal Shape ◽

Fabric Diagrams

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Three Concepts of Fabric Statistics (Curie 1884, Schmidt 1925, and Niggli 1948) and Their Modifications and Elaborations, A Historical Discussion

Earth Sciences History ◽

10.17704/eshi.7.2.kt351783323j2m70 ◽

1988 ◽

Vol 7 (2) ◽

pp. 121-125

Author(s):

Martin Kirchmayer ◽

F. Germany

Keyword(s):

Pure Sciences ◽

Thin Section ◽

General Symmetry ◽

3 Dimensional ◽

Entire Field ◽

Rock Types ◽

Fabric Diagrams ◽

Universal Stage ◽

The U.S

There are three concepts of fabric statistics: (1) the NEUMANN-MINNIGERODE-CURIE (1884) concept; actually Curie originated the fabric models, based on crystallographic elements of the cause-symmetry, media-symmetry, and effect-symmetry. (2) the SCHMIDT (1925) or SANDER (1930) concept classifies fabric diagrams keyed to rock types and to the kind of deformation, and is based on 5 types of tectonites. (3) the NIGGLI (1948) concept, a general symmetry concept, referring to morphology, which can be applied to all media in the entire field of natural and pure sciences. All three concepts are typically European. In the 1920's and 1930's some American researchers travelled to Europe to study the techniques of fabric statistics. Among them was Haff (1938) who holds the American priority. Today universal stage research is not very common in the U.S.; instead, macrofabrics are studied by geological compass. In the application of the Schmidt-Sander concept to geological environments, Rueger (1928) of Heidelberg holds the priority. This paper compares the three concepts, and deals with their developments and elaborations in Europe, in regard to their use in a precise 3-dimensional way, on a thin section scale.

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