江山-绍兴断裂带铁沙街组变流纹岩SHRIMP锆石U-Pb测年及其意义

    Geochronographic dating of the Tieshajie Formation in the Jiangshan-Shaoxing fault zone and its implications

    • 摘要: 隶属华夏北缘、地处江绍断裂带中的铁沙街组变流纹岩的SHRIMP锆石U-Pb年龄分别为1132 Ma±8Ma,1140 Ma±7Ma,1143 Ma±9Ma和1172Ma±10Ma。同时通过年龄数据探讨位于该断裂带中的田里片岩和周潭群、万源群的构造背景。该年龄数据对限定江绍断裂带区域地层对比和构造演化都有着重要意义。上述锆石U-Pb年龄表明,江绍断裂带(萍-绍断裂带)存在1.1Ga左右孤岛的沉积地层,代表了华夏地块向扬子地块俯冲的中间岛弧,而怀玉地区为弧后拉张盆地;该年龄为江绍断裂带中变质地层的对比提供了可靠的年龄依据。

       

      Abstract: This paper will report some SHRIMP U-Pb ages (1132Ma±8Ma, 1140Ma±7Ma, 1143Ma±9Ma and 1172Ma±10Ma) of meta-rhyolite of the Tieshajie Formation in the Jiao-Shao fault zone, which belongs to the Northern margin of Cathaysia. Combine of those dating, we will try to discuss the tectonic set of the Tianli schist, Zhoutan Complex and Wanyuan Complex. According to the isotopic dating, it is important for limit the strata correlation and tectonic evolution in the Jiao-Shao fault zone. The dating above mentioned shows the depositional strata of an ace-basin system in 1.1Ga, which is represented inner ace between the Yangtze and Cathayasia and the Huaiyu area is an extensional basin of the back-are. The chronostratigraphic dating of the Tieshajie Formation proved the reliable isotopic evidence for the correlation of the metamorphosed strata in the Jiang-Shao fault zone.

       

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