冀西北怀安地区基底变质岩系构造变形序列研究

怀安地区构造变形强烈,是研究华北克拉通形成和演化的重要窗口。通过对该区基底变质岩系构造形迹进行研究,结合区域地质资料及同位素年龄数据,将该区早前寒武纪构造变形序列划分为4期: 新太古代阜平晚期(D1),桑干岩群韧性变形,形成片麻理、无根褶皱和韧性剪切带; 新太古代五台晚期(D2),在新太古代TTG/花岗岩中形成区域性片麻理和条带状构造,并在桑干岩群中形成近EW向的复式背形和向形构造; 古元古代吕梁中期(D3),集宁岩群沙渠村岩组形成区域性片麻理,并形成与片麻理一致的NE向韧性剪切带,在新太古代地质体中叠加近SN向的开阔复式背形和向形构造; 古元古代吕梁晚期(D4),红旗营子岩群太平庄岩组形成片理和片麻理,尚义—平泉断裂形成。建立了该区早前寒武纪构造演化模式,并将其划分为新太古代陆壳增生阶段和古元古代碰撞造山阶段,对理解华北克拉通的形成及演化具有重要意义。

Study on tectonic deformation sequence of the basement metamorphic rock series in Huai'an of Northwestern Hebei

Huai'an, with strong tectonic deformation, is an important place to understand the formation and evolution of North China Craton. Based on the investigation of structural deformation in the basement metamorphic rock series, and combined with the regional geological data and isotopic age data the Early Precambrian deformation sequence is divided into four periods. The first stage is late Fuping movement of New Archean (D1). Sanggan Group was ductile deformed to form gneiss, rootless folds and ductile shear zone. The second stage is late Wutai movement of New Archean (D2). The schistosity and banded structures of TTG were formed in the New Archean. Simultaneously, EW antiformorium was formed in the Sanggan Group. The third stage is middle Lvliang movement of Palaeoproterozoic (D3). Regional schistosity was formed in Jining Group of Shaqucun petrofabric, and NE ductile shear zone was also formed.SN antiformorium was superimposed on the New Archean geological bodies. The fourth stage is late Lvliang movement of Palaeoproterozoic (D4). Schistosity was formed in Hongqiyingzi Group of Taipingzhuang petrofabric, and Shangyi-Pingquan Fault was formed. Inaddition, the Early Precambrian tectonic evolution model of this area was established, and it was divided into two stages: continental crust accretion in New Archean and collision orogeny in Paleoproterozoic, Which is of great significance in understanding the formation and evolution of North China Craton.