Acta Scientiarum Naturalium Universitatis Pekinensis

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An Initial Research on the Extension Deformation Belt in the Archean Metamorphic Rocks in the Northern Taihang Mountains

TANG Xianmei, LIU Shuwen   

  1. Department of Geology, Peking University, Beijing, 100871
  • Received:1996-11-21 Online:1997-07-20 Published:1997-07-20


唐先梅, 刘树文   

  1. 北京大学地质学系,北京,100871

Abstract: The Archean metamorphic rocks in the northern Taihang Mountains can be divided into Fuping Gneiss Complex (FPGC), Nanying Gneiss (NYG) and Wanzi Layering Series (WZLS) from bottom to top. A large low-angle-extension deformation belt, along which NYG was emplaced, was found between FPGC and WZLS. A series of ductile deformation structures, including a-type and sheath folds, mineral stretching lineations and augen structures, are found in the main deformation belt, where rocks have been foliated heavily. Shear criteria indicate a top-to-the-west sense of shear. A series of small shear zones, which are parallel to the main deformation belt, are formed in the foot wall, while in the hanging wall ductile-brittle normal faults are popular. The PT-paths of the two walls are clockwise, implying that the crust evoluted from early thicking by folding through thinning by stretching and finally being denuded by lifting.

Key words: Northern Taihang Mountains, Archean, Extension Deformation Belt, P-T path

摘要: 太行山北段太古宙的变质岩系自下而上分为阜平片麻杂岩、南营片麻岩和湾子层状岩系。阜平片麻杂岩和湾子层状岩系之间发育一条大规模低角度伸展变形带,沿该变形带南营片麻岩侵位。主变形带内部岩石发生强烈片理化,发育A型褶皱、鞘褶皱和眼球状岩块构造等韧性变形构造。其中矿物拉伸线理近 EW 向,剪切标志指示上盘(湾子岩系)向西,下盘(阜平片麻杂岩)向东的运动学特征。下盘发育平行于主变形带的小型韧性剪切带,上盘发育一系列铲形脆韧性断裂系。上、下两盘的PTt轨迹均为顺时针型,显示了地壳由褶皱增厚到拉伸减薄的隆升演化过程。

关键词: 太行山北段, 太古宙, 伸展变形带, PTt轨迹

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