Fabric (geology)
Ingeology,arock'sfabricdescribes the spatial and geometric configuration of all the elements that make it up.[1][2]Insedimentary rocks,the fabric developed depends on thedepositional environmentand can provide information on current directions at the time of deposition. Instructural geology,fabrics may provide information on both the orientation and magnitude of the strains that have affected a particular piece of deformed rock.
Types of fabric
[edit]- Primary fabric — a fabric created during the original formation of the rock, e.g. a preferred orientation ofclastlong axes in aconglomerate,parallel to the flow direction, deposited by a fast waning current.
- Shape fabric — a fabric that is defined by the preferred orientation of inequant elements within the rock, such as platy- or needle-like mineral grains. It may also be formed by the deformation of originally equant elements such as mineral grains.[3]
- Crystallographic preferred orientation— in plastically deformed rocks, the constituent minerals commonly display a preferred orientation of their crystal axes as a result ofdislocationprocesses.
- S-fabric — a planar fabric such ascleavageorfoliation;when it forms the dominant fabric in a rock, it may be called an S-tectonite.
- L-fabric — a linear fabric such as mineral stretchinglineationwhereaggregatesof recrystallised grains are stretched out into the long axis of the finitestrain ellipsoid,where it forms the dominant fabric in a rock, it may be called an L-tectonite.
- Penetrative fabric — a fabric that is present throughout the rock, generally down to thegrain scale,although this does also depend on the scale at which the observations take place.[4]
- Magnetic fabric — orientation of magnetic particles within a rock sample or in soils to determinepaleomagnetic history[5]or to quantify tectonic strain.[6]
References
[edit]- ^Hobbs BE, Means WD, & Williams PF. (1976).An outline of structural geology.John Wiley & sons, p.73.
- ^Twiss RJ and Moores EM. (2007).Structural Geology,2nd Edition, WH Freeman and Co., p.497.
- ^Park, R.G. (2004).Foundation of Structural Geology(3 ed.). Routledge. p. 52.ISBN978-0-7487-5802-9.
- ^Passchier, CW; Trouw, RAJ (2005).Microtectonics(2 ed.). Springer. p. 315.ISBN978-3-540-64003-5.Retrieved14 October2010.
- ^Butler, Robert F. (1992).Paleomagnetism: magnetic domains to geologic terranes.Boston: Blackwell Scientific Publications.ISBN086542070X.OCLC23254791.
- ^Borradaile, Graham John (December 1988). "Magnetic susceptibility, petrofabrics and strain".Tectonophysics.156(1–2): 1–20.Bibcode:1988Tectp.156....1B.doi:10.1016/0040-1951(88)90279-X.
See also
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