华北克拉通中部带中段古元古代构造格架与主要变形事件研究

古元古代是华北克拉通构造演化的关键时期，中部带的性质是近年来华北克拉通构造演化研究争论的焦点之一。文中根据古元古代韧性剪切带重新划分了中部带北段构造格架，即由近EW向朱家坊韧性剪切带、NEE向王家会韧性剪切带和NE向龙泉关韧性剪切带分割恒山、繁峙、五台和阜平地块。这些地块基底具有不同的前寒武纪变质杂岩组成、构造变形特征和构造演化历史，一般都具多期变质变形叠加的特征。研究表明华北克拉通中部构造带北段在古元古代末发生3次重要的构造变形事件：繁峙地块由SW向NE方向的构造挤入，挤入过程中导致五台地块变形并向南东方向逆冲(D1)；以阜平地块为核部的大规模伸展抬升，阜平变质杂岩抬升至近地表，阜平地块与五台地块之间形成一系列低角度伸展型韧性剪切带(D2)；最后一次构造事件是NE向拉伸导致的大量NW向基性岩墙群侵位(D3)。

Tectonic framework and deformation events in the central Trans-North China Tectonic Belt during the Late Paleoproterozoic

The Paleoproterozoic is a key period in the tectonic evolution of the North China Craton. Recently, the geologic property of the Trans-North China Tectonic Belt (TNCTB) has become the most controversial and focal point in the study of the North China Craton. In this paper, we redefined the tectonic framework of central TNCTB based on several convincing Paleoproterozoic ductile shear zones, including the Zhujiafang(EW-trending), the Wangjiahui(NEE-trending)and the Longquanguan(NE-trending) ductile shear zones, as they divided several Precambrian blocks named as Hengshan, Fanshi, Wutai, and Fuping. Different Precambrian metamorphic complex of unique composition formed the basement of each block, which has its own deformation characteristics and tectonic evolution history. These blocks have generally experienced multiple stages of metamorphism and deformation events. According to our research, three important tectonic events occurred in central TNCTB at the end of the Paleoproterozoic. First, the extrusion of the Fanshi block from SW to NE resulted in the deformation and southeastward thrusting of the Wutai block (D1). Next, the uplifting of the Fuping block and large-scale extension caused the Fuping complex uplifted to the near-surface (D2), which formed a series of low-angle and top-to-NW stretching ductile shear zones between the Fuping and Wutai blocks. Finally, NE-trending extension of the North China Craton led to the emplacement of the NW-trending mafic dykes swarm(D3).