PROGRESSIVE DEFORMATION AND REORIENTATION OF FOLD AXES IN A DUCTILE MYLONITE ZONE - WOODROFFE THRUST
PROGRESSIVE DEFORMATION AND REORIENTATION OF FOLD AXES IN A DUCTILE MYLONITE ZONE - WOODROFFE THRUST
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DOI：
10.1016/0040-1951(78)90074-4
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发表时间：
1978-01-01
期刊：
影响因子：
2.9
通讯作者：
BELL, TH
中科院分区：
文献类型：
--
作者：
BELL, TH
The structural geometry of a mylonite zone (the Woodroffe thrust) and the country rock in its immediate vicinity is described. Mylonitic schistosity formed axial planar to folds in country rock foliation and contains a mineral elongation lineation which is constant in orientation. However, the fold axes (and associated intersection lineation) spread in orientation within the mylonitic schistosity but with a strong maximum parallel to the mineral elongation lineation. It is demonstrated that the fold axes formed initially at approximately 90° to mineral elongation but rotated with increase in strain towards it. Where this phenomenon was homogeneous on a macroscopic scale, rotation of large blocks of country rock across zones of mylonitization accompanied reorientation of fold axes within the mylonite.The controversy of progressive simple versus progressive pure shear for mylonite zones is discussed in the light of recent fabric and other evidence. It is concluded that theinhomogeneousforms of both progressive pure shear and progressive simple shear played a part and that the former dominated initially but gradually gave way to the latter until brittle rupture with large simple-shear displacements on a zone lubricated by the formation of pseudotachylite, brought granulite over amphibolite facies rocks.
