Mylonite

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mylonite

[′mī·lə‚nīt]
(petrology)
A hard, coherent, often glassy-looking rock that has suffered extreme mechanical deformation and granulation but has remained chemically unaltered; appearance is flinty, banded, or streaked, but the nature of the parent rock is easily recognized.

Mylonite

 

finely ground, crushed rock formed by the movement of rock masses along the surface of tectonic faults. As a result of great pressure, the rocks (granite, gneiss, schists, quartzite) are crushed and ground into a compact state. Microscopic analysis makes possible the identification of finely ground mica flakes and minute quartz and feldspar fragments in the finely pulverized mass, which is made up of the softer minerals of the primary rock and sometimes such new formations as sericite and zoisite. Unlike cataclasis, mylonitization represents the final stage in the crushing of rock into microscopic form. Mylonite zones are located along the major regional thrust faults in the Urals, Tien-Shan, the Caucasus, and the Altai. These zones are several hundred meters wide and extend several dozen kilometers.

REFERENCE

Polovinkina, Iu. I. Struktury i tekstury izverzhennykh i metamorficheskikh porod, vol. 2, part 2. Moscow, 1966.
References in periodicals archive ?
Moreover, a great quantity of winding and rub can not only produce more mylonite or other broken coals but also seal original cleats, micro-fractures, and seepage pores for C[O.sub.2] transport [49].
A shear zone of about 10 m thick is associated to this fault, mainly constituted by foliated cataclasites and mylonites (Fig.
In the case of LF1 quartz mylonite, we have simulated different AMS responses based on quantitative texture analysis.
Ductile fault zones (mylonites) show elongated cavities along the foliation, showing evidences of fluid circulations.
In the west, the Strazek Moldanubicum is demarcated by the Pribyslav mylonite zone; in the northeast the Strazek Moldanubicum joins the Nasavrky Massif, or the southernmost spur of the Hlinsko zone and the Svratka crystalline complex.
P-T conditions have been constrained using geothermobarometers in high temperature mylonites while to constraint the P-T conditions during the ductile to brittle tectonic evolution of the MCTZ zone fluid inclusion analyses have been performed on quartz lenses from kyanite bearing gneisses and micaschists sampled from the Main Central Thrust Zone and in quartz inclusions trapped in garnet crystals.
North Tirek- The Tirek North licence is located on the eastern edge of the In Ouzzal mole, which consists of a band of mylonites between 300 and 3,000 metres thick corresponding to a major tectonic deformation rift (called the In Ouzzal Fault Zone).
On the northern part of the Miroslav horst are placed the mylonites of Brunnia, on its southern part and in the Krhovice foreland Moravicum and on the south Dunkelsteiner Moldanubicum.
It is built up of metadacites, phyllites, mica schists, gneisses, and mylonites.
Authors divided fault rocks into three basic types namely cataclasites, mylonites and metamorphic rocks.
In the west of Iran recognized shear zone, accommodated mylonite zone that related to the closure of Neo-Tethys and Zagros orogeny contractional event (Mohajjel and Fergusson, 2000; Agard et al., 2005; Allen and Amstrong, 2008; Agard et al., 2011; Mouthereau et al., 2012).