3 edition of Planar and linear fabrics of deformed rocks found in the catalog.
Planar and linear fabrics of deformed rocks
|Statement||Special editors: P.L. Hancock,... (et al).|
|Series||Journal of structural geology -- vol.6, no.1/2|
|Contributions||Hancock, P. L.|
Fabric elements are aligned in some manner (e.g. deformed rocks. How many types of preferred fabrics? 2, foliation and lineation. Both linear and planar fabrics dominate (both foliation and lineation). Different foliations. expressed as 'S' and a subscript to denote timing S1 (older)- S2 (younger) and so on. S0 is used to refer to bedding. Estimating the kinematic vorticity numbers from rock fabrics presents many problems. It depends on the qualitative observation of deformed linear or planar elements in competent sub-fabrics of.
• Random fabric – elements show no preferred orientation • Primary fabric – characteristic of the original rock • Tectonic fabric – result of deformation Fabric is a configuration of objects penetrating the rock. Linear objects form L-fabrics (top) while planar objects constitute S-fabrics (bottom). The rocks . Generally, a lineation is a term used to describe linear elements in a rock, this can occur in deformed or undeformed rocks (Fossen ). Lineations are geometrical arrangement of component features in the rock (fabric element) in which one dimension is considerably longer than the other two dimensions, as seen in the diagram below (Fossen ).
While in the process of being deformed, minerals may start to align themselves in accordance with the deforming force, usually approx. perpendicular to the main stress. These newly oriented minerals will form a foliation which is a second planar surface in the rocks and not necessarily parallel to the first planer surface. Foliation is any penetrative planar fabric or layering in a rock. (Marshak & Mitra, ) Gorge Vermoont, US. (Vermont Geological Survey) Lineation. Is a prefered linear alignment of elements in rocks. (Davis & Reynolds, zone with subparallel boundaries in which rocks are more highly deformed than rocks adjacent to the zone.
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Planar and Linear Fabrics of Deformed Rocks 30 August-2 September • ETH, Zürich P. H a n c o c k, E. K l a p e r, N. M a n c k t e l o w, J. R a m s a y Volume 6, Issues 1–2. Crystallographic preferred orientation — in plastically deformed rocks, the constituent minerals commonly display a preferred orientation of their crystal axes as a result of dislocation processes.
S-fabric — a planar fabric such as cleavage or foliation; when it forms the dominant fabric in a rock, it may be called an S-tectonite. Foliations and Lineations During deformation, rock forming grains and minerals change their orientation and shape, giving deformed rocks organized planar and linear structures called fabrics.
Planar fabrics resulting from deformation are called schistosity or foliation. Get this from a library. Planar and linear fabrics of deformed rocks: a selection of papers delivered at an International Conference held at ETH Zürich, 30. igneous rocks. In structural geology we are most interested in fabrics that originate when rocks are deformed.
Fabrics are common in folded rocks, and if fabrics develop at the same time as folding they often have a very specific relationship to folds.
Fabrics may be planar or linear. Planar fabrics File Size: KB. Tectonites • Rocks with a penetrative tectonic fabric are also called tectonites. • When linear fabric elements dominate, the rock is called an L- tectonite, whereas a rock with dominantly planar fabrics is called an S-tectonite, and, not surprisingly, rocks with both types of fabric elements are called LS-tectonites.
Structural geology is the study of the three-dimensional distribution of rock units with respect to their deformational histories. The primary goal of structural geology is to use measurements of present-day rock geometries to uncover information about the history of deformation in the rocks, and ultimately, to understand the stress field that resulted in the observed strain and geometries.
In the fabrics of most metamorphically deformed rocks some degree of parallel alignment of planar or linear fabric elements is evident. Such rocks are said to be schistose or foliated. Although these two terms have been used in different senses by some writers [Harker, ], in this paper schistosity and foliation are defined synonymously to include all parallel fabrics of metamorphic origin.
This paper examines the geological implications of an analysis of constraints on the orientation of fold axes in orthotropic materials. We argue that. linear scratch marks. rocks deformed under low to moderate temperatures may develop a planar fabric along which they break called rock.
cleavage. gneiss. alternative dark and light bands; a banded, compositional foliation. phyllite. and interaal linear fabrics of rocks. Jones (), Turner and Weiss () and Whitten () favour usage of the term to linear fabrics penetrative in hand specimens as well as in small exposures.
Hills() considered all linear components, sui generis having linear habit as lineation, Cogenetic linear elements may have variable morphology.
LINEAR STRUCTURAL ELEMENTS. Lineation. is a general term to describe any repeated, commonly penetrative and parallel alignment of linear elements within a rock (to envision lineation, imagine packages of spaghetti).
A lineation may be a primary igneous or sedimentary fabric element, such as an array of elongate K-feldspar. Metamorphic rock - Metamorphic rock - Major features: The most obvious features of metamorphic rocks are certain planar features that are often termed s-surfaces.
The simplest planar features may be primary bedding (akin to the layering in sedimentary rocks). As the rock crystallizes or recrystallizes under directed pressure, new crystals may grow in some preferred direction, sometimes. In structural geology the term fabrics mean the arrangement of component featuresof therock.
Fabricsinclude-foliation and leneation Foliation is any closely-spaced, systematically oriented planar feature that occurs penetratively in a body of rock, and commonly associated with is a characteristic of tectonites, i.e., rocks formed by.
Continuous Fabric - continuous on millimeter scale. Continuous Fabric at Ait Ahmane, Bou Azzer, Morocco. Spaced Fabric - visible spacing between fabric elements. Domains- deformed planar element Microlithons- undeformed rock layers between Domains Two main classes: Foliation - planar fabric Lineation - linear fabric.
- 1-dimensional: linear - 2-dimensional: planar. Accordingly, it is conventional to distinguish - L fabrics, characterized by elongated elements whose long axes cluster close to a unique line. The rocks, L-tectonites, have a dominant linear fabric.
- S fabrics, where the long axes of essentially flat fabric elements cluster strongly near a plane. Another effect that is commonly observed in crystals deformed at low temperature by intracrystalline deformation are lamellae with a high optical relief which usually have a distinct preferred orientation, known as deformation lamellae, also known as Fairbairn lamellae.
Deformation lamellae are particularly common in quartz. III Planar fabrics A Deformation induced layering; fabric elements parallel a common plane B Metamorphic foliation (visible alternation of layers of qtz & feldspar with mica, e.g., schistosity and layering in gneiss) IV Linear fabrics A Fabric elements parallel a common line B Can be due to intersection of two non-parallel planar fabrics.
Definitions for and description of fabrics. foliation: any planar, relatively penetrative (through going), fabric in a rock that is not are due to the interaction of deformational processes and metamorphic processes. lineation: a relatively penetrative fabric in a rock that is not primary and which has a linear geometry.
Image to right of a schematic representation of a. In structural geology, a fold occurs when one or a stack of originally flat and planar surfaces, such as sedimentary strata, are bent or curved as a result of permanent deformation.
Synsedimentary folds are those due to slumping of sedimentary material before it is in rocks vary in size from microscopic crinkles to mountain-sized folds. The discussion then turns to the distribution of planar and linear parallel-fabrics in geological bodies; constructive restoration of earlier geometry of tectonic fabrics; tectonics of intrusives with a high susceptibility to componental movement; and mechanical deformation and metamorphism of rocks.Abstract.
The geometrical data for structural interpretation in geology become available through plotting the attitude of planar or linear structures and textures, including both those which being visible to the naked eye may be mapped in the field, and those that can be determined only under the microscope, and must accordingly be studied in the laboratory.Sedimentary rocks deformed at shallow crustal depth can show a wide variety of planar, linear and mixed planar-linear fabrics depending on their structural position within folds.
A model has been developed which tries to explain this variation in fabric development in terms of the strain states that it represents. We analyse the finite strain states that may develop during compaction and.