高级检索

    湖北红安群的时代:变质花岗质侵入体U-Pb定年提供的制约

    Timing of the Hong′an Group in Hubei:Constraints from U-Pb dating of metagranitic intrusions

    • 摘要: 提要:湖北红安群的原岩形成时代一直是个有争议的问题。笔者对红安群中两个不同类型的花岗质侵入体进行了锆石U-Pb定年,在位于红安群之下的双峰尖岩体中获得岩浆侵位年龄为(813±6) Ma,在侵入于红安群中的高格岩体获得岩浆侵位年龄为(638±142) Ma,高压变质年龄为(229±22) Ma。结合目前在扬子板块和大别造山带内部获得的一系列新元古代年代学数据,认为红安群变质杂岩中沉积地层的形成时代应限制在825~630 Ma之间,是扬子大陆基底在新元古代裂解的产物。这套岩石在印支期(约230 Ma)华北与扬子板块碰撞过程中经历了低温高压蓝片岩—榴辉岩相变质作用。

       

      Abstract: Abstract:The age of the protolith of the Hong′an Group in Hubei has been a controversial issue. Zircon U-Pb dating of different types of granitic intrusions in the Hong′an Group suggests that the Shuangfengjian granite lying unconformably below the Hong′an Group was emplaced at 813±6 Ma, whereas the Gaoge granite was intruded into the Hong′an Group at 638 ±142 Ma and metamorphosed at high pressure at 229±22 Ma. On that basis, combined with a number of Neoproterozoic age data obtained from the Yangtze craton and the Dabie orogen, it is believed that the ages of the sedimentary sequences in the metamorphic complex of the Hong′an Group, which are the product of the break-up of the Yangtze craton in the Neoproterozoic, should be limited in the range of c. 825~630 Ma. These sequences underwent low-temperature and high-pressure blueschist to eclogite facies metamorphism during the Indosinian (c. 230 Ma) collision between the North China and Yangtze cratons.

       

    /

    返回文章
    返回