华北克拉通南缘嵩山-箕山地区构造变形解析

The North China Craton, one of the oldest cratons in the world, formed during development of the Columbia Supercontinent. It is limited in knowledge of development and evolution of the Trans-North China Orogen (TNCO), such as timing of collisional event, polarity of the subduction, and so on, which restricts understanding on all-around evolution history of the North China Craton. The Dengfeng Complex is one of Neoarchean granite-greenstone belts, located in southern part of the TNCO and overlying by the Songshan Group, which experienced distinct deformation and thus are key objects for analysis Palaeoproterozoic tectonic evolution of the TNCO. Based on detailed field observation, this project will take exhaustive structural analysis of the Dengfeng Complex and the Songshan Group, cropping out in the Songshan-Jishan area, and thus obtain their deformation characteristics and stages. Synchronously, thermochronological works will be done to obtain deformation time of the Dengfeng Complex and the Songshan Group. Combined with these results, tectonic evolution history of the Songshan-Jishan area will be discovered. Simultaneity, this project will look for Palaeoproterozoic magmatites and find out tectonic setting of the Southern North China Craton through detailed geochemical works. Based on summary of abundant previous achievements, comprehensive analysis on development and evolution of the TNCO and further offering evidences for constructing a whole tectonic evolution history of the North China Craton.

华北克拉通是地球上最古老的克拉通之一，形成于全球哥伦比亚超大陆聚合事件中。位于东部、西部陆块之间的华北中部造山带的形成演化过程，包括其形成时间、俯冲极性等相关内容，仍然了解有限，从而限制了对华北克拉通完整演化历史的认识。登封杂岩是位于华北克拉通南缘的太古代花岗-绿岩带之一，与上覆的古元古代嵩山群均经历了明显的构造变形，是分析华北中部造山带古元古代构造演化的关键研究对象。本项目将通过野外观察与填图，对嵩山-箕山地区出露的登封杂岩、嵩山群开展详细的构造变形分析，查明其变形特征与变形期次；同步开展构造-热年代学工作，获得登封杂岩、嵩山群变形时间，查明嵩山-箕山地区构造演化历史。同时在华北克拉通南缘寻找古元古代岩浆岩，通过精细的地球化学特征研究，厘清古元古代华北克拉通南缘大地构造背景。在总结已有的丰富成果的基础上，分析华北中部造山带的形成演化过程，进而为建立完整的华北克拉通构造演化历史提供证据。

嵩山-箕山地区位于华北克拉通南缘、华北中部造山带南部，是记录华北克拉通形成过程中东部陆块与西部陆块拼合过程相关信息的重要地区。嵩山-箕山地区构造变形复杂，表现为多个时代构造变形相互叠加。本项目通过详细的构造解析与年代学工作，将华北中部造山带同造山期的构造变形剥离了出来，查明了嵩山-箕山地区总体展布及几何学运动学特征，获得了同造山期构造应力方向为NW-SE向的认识；通过针对嵩山群石英岩和五指岭组绢云母石英片岩详细的和太古代片麻岩锆石定年结果，揭示了石英岩和绢云母石英片岩的原岩物源区均为近源的太古代片麻岩，对嵩山-箕山地区登封杂岩、嵩山群的形成时间有了新的认识；通过对石称岩体和熊耳群火山岩的详细考察，厘定了嵩山-箕山地区古元古代以来存在多期伸展事件，获得了嵩山-箕山地区自18亿年以来并未遭受大规模的构造运动；位于嵩山-箕山地区的龙王瞳岩体在16亿年侵位之后，又受到了晚侏罗世岩浆岩的侵位叠加。