陕南汉中地区新元古代岩浆岩U-Pb年代学

geochronology of Neoproterozoic magmatic rocks in Hanzhong, southern Shaanxi, China. Geological Bulletin of China,

用单颗粒锆石U-Pb稀释法测定了扬子地块北缘汉南地区新元古代岩浆岩的年龄,获得孙家河组火山岩成岩年龄为840～ 820Ma,汉南侵入杂岩中五堵门复式花岗岩体中英云闪长岩的结晶年龄为764Ma±2Ma,黄家营复式岩体中钾长花岗岩的结晶年龄为778Ma±5Ma,表明扬子地块北缘汉南地区岩浆岩分别形成于新元古代晋宁期和澄江期。结合这些岩浆岩的地质和地球化学特点,认为其成因可能与华南新元古代裂解事件有关。

Single-zircon U-Pb dilution dating of Neoproterozoic igneous rocks in the Hannah area, southern Shaanxi, on the northern margin of the Yangtze block yields ages of 840-820 Ma for volcanic rocks of the Sunjiahe Formation and ages of 764±2 Ma for tonalities in the Wudumen composite granite and 778±5 Ma for K-feldspar granites in the Huangjiaying composite intrusion in the Hannah intrusive complex, respectively. These isotopic ages suggest that igneous rocks in the Hannan area on the northern margin of the Yangtze block formed in the Neoproterozoic Jinningian and Chengjiangian periods. These ages combined with the geological and geochemical characteristics of these igneous rocks suggest that their origin are probably related to the Proterozoic breakup of south China block.