STUDY OF THE PROPERTIES OF SYNTECTONIC PORPHYROBLASTS IN DABEIWU AREA,JIANGXI PROVINCE
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摘要: 大背坞地区浅变质碎屑岩内的韧性剪切带中发育有同构造成因的菱铁矿变斑晶和黄铁矿变斑晶,它们是进变质剪切变形的产物和标志。作为同构造成因,这类变斑晶的发育与剪切变形及强度、变形变质矿物绢云母的含量和晶体大小关系密切,具有独特的晶形并保留基质片理等特征。根据变斑晶的旋转效应可以恢复大背坞韧性剪切带的成生演化历史:右行逆冲剪切→压扁变形→左行正断剪切.Abstract: The syntectonic porphyroblasts of pyrite and siderite in the ductile shear zone developed in epimetamorphic clastic rocks in Dabeiwu area are the products and marks of ductile shear deformation during progressive metamorphism.The porphyroblasts being of syntectonic origin have attained the following features:their growth is correlated with deformation intensity,content of sericite and size of the crystal,and the porphyroblasts have their distinct crystal forms and retain the schistosity of groundmass.From the rotation of the pophyroblasts,the authors reconstruct the evolution of Dabeiwu ductile shear zone:from left-lateral reverse-slip through flattening deformation to right-lateral normal-slip.
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Key words:
- syntectonic origin /
- porphyroblast /
- Dabeiwu area
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