Geometric aspects of synkinematic granite intrusion into a ductile shear zone — an example from the Yunmengshan core complex, northern China
Geometric aspects of synkinematic granite intrusion into a ductile shear zone — an example from the Yunmengshan core complex, northern China
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DOI：
10.1144/gsl.sp.2005.245.01.04
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发表时间：
2005
期刊：
影响因子：
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通讯作者：
C. Passchier;J. S. Zhang;J. Konopásek
中科院分区：
文献类型：
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作者：
C. Passchier;J. S. Zhang;J. Konopásek
摘要中国北方白垩系永蒙山岩心杂岩包含一个大型同构造花岗闪长岩基，它侵入了一个稍老的闪长岩侵入体。沿闪长岩和花岗闪长岩的接触面发育一条主要的缓倾韧性剪切带。在高变质条件下，剪切带活动期间，与主花岗闪长岩基伴生的大量花岗岩脉和伟晶岩脉侵入剪切带。随着剪切带的线理和叶理作用的平行，逐渐变老的脉体更强烈地变形成紧密的圆柱形褶皱结构。脉与叶理平行的部分原因是这种旋转，但也与同构造时期的伟晶岩脉与叶理平行注入有关。已经发现了几种可以区分脉体固态变形的小尺度结构。花岗岩岩脉在韧性剪切带上方延伸不多，韧性剪切带似乎是一个盖层，是一个有效的储物库，防止花岗岩岩脉从下伏基底侵入。在剪切带的下盘和下部，由于脉体侵入，体积增加较多。
Abstract The Cretaceous Yungmengshan core complex in northern China contains a large syntectonic granodiorite batholith that intrudes a slightly older diorite intrusion. A major gently dipping ductile décollement shear zone is developed along the contact of the diorite and granodiorite. The shear zone is invaded by a large volume of granitic and pegmatite veins associated with the main granodiorite batholith during activity of the shear zone under high-grade metamorphic conditions. Progressively older veins are more strongly deformed into tight cylindrical fold structures rotated into parallelism with the lineation and foliation in the shear zone. Parallelism of veins to the foliation is partly due to this rotation, but also to foliation-parallel injection of younger syntectonic pegmatite veins. Several small-scale structures have been recognized that allow distinction of solid-state deformation of veins. Granite veins do not extend much above the ductile shear zone that seems to act as a lid and an effective depository to intruding granite veins from the underlying batholith. There was considerable volume increase in the footwall and lower part of the shear zone by vein intrusion.