CAJ | 학술논문

秦岭造山带的构造演化是理解华北与扬子陆块缝合过程的关键，位于商丹断裂带以南的刘岭群是揭示秦岭造山带晚古生代构造演化历史的重要窗口。采用LA-ICP-MS对刘岭群3个变质砂岩样品中的碎屑锆石进行了U-Th-Pb同位素测定，获得最年轻的一组年龄区间为377~395Ma，主要年龄峰值约为442Ma、780~850Ma和900~970Ma，表明刘岭群沉积时代可以持续到晚泥盆世，物质来源于北秦岭构造带。结合刘岭群北侧武关杂岩的最新研究成果可以确定，刘岭群和武关杂岩共同构成了华北陆块南缘中-晚泥盆世弧前盆地的沉积序列，暗示古秦岭洋的最终闭合发生在泥盆纪之后，而华北与扬子陆块碰撞的主缝合线应位于刘岭群的南侧。
진령조산대적구조연화시리해화북여양자륙괴봉합과정적관건，위우상단단렬대이남적류령군시게시진령조산대만고생대구조연화역사적중요창구。채용LA-ICP-MS대류령군3개변질사암양품중적쇄설고석진행료U-Th-Pb동위소측정，획득최년경적일조년령구간위377~395Ma，주요년령봉치약위442Ma、780~850Ma화900~970Ma，표명류령군침적시대가이지속도만니분세，물질래원우북진령구조대。결합류령군북측무관잡암적최신연구성과가이학정，류령군화무관잡암공동구성료화북륙괴남연중-만니분세호전분지적침적서렬，암시고진령양적최종폐합발생재니분기지후，이화북여양자륙괴팽당적주봉합선응위우류령군적남측。
The tectonic evolution of the Qinling orogen is the key to understanding the assembly of the North China and South Chi-na blocks. The Liuling Group in the south of the Shangdan fault can provide an important window for detecting the Late Paleozoic evolutionary process of the Qinling orogen. The LA-ICP-MS U-Pb ages of detrital zircons from three metasandstone samples from the Liuling Group show a age spectrum with major populations at ca. 442Ma and in the range of 780~850Ma and 900~970Ma, with the youngest population being ca. 377~395Ma. These data suggest that the deposition of the Liuling Group might have lasted to the Late Devonian, and sediments were probably derived from the North Qinling tectonic belt. In combination with the recent investiga-tion of the Wuguan complex in the north of the Liuling Group, the authors infer that a Middle to Late Devonian turbidite sequence might have formed in a fore-arc basin on the southern margin of the North China block, and the closure of the Paleo-Qinling ocean might have occurred after Devonian. Hence, the collisional boundary of the North and South China blocks should be located in the south of the Liuling Group.