浙江诸暨地区石角-璜山侵入岩LA-ICP-MS锆石U-Pb年龄——对超镁铁质球状岩成因的启示

    LA-ICP-MS zircon U-Pb ages of the Shijiao-Huangshan intrusive rocks in Zhuji area, Zhejiang Province: implications for the petrogenesis of the ultramafic orbicular rocks

    • 摘要: 对分布于江南造山带东段江绍断裂带附近的浙江诸暨地区石角-璜山侵入岩进行了LA-ICP-MS锆石U-Pb定年工作,石角角闪辉石岩和璜山石英闪长岩的结晶年龄分别为844Ma±3Ma和818Ma±6Ma。该年龄结果表明,石角村附近的超镁铁质岩(包括球状辉闪岩)与其外围的闪长岩可能并非同时形成。江绍断裂带附近分布的多个闪长岩体的形成时代介于930~820Ma之间。对这些超镁铁质岩和闪长岩的精细岩石成因研究将有助于揭示扬子和华夏在新元古代时期的拼接过程。

       

      Abstract: LA-ICP-MS zircon U-Pb dating work was carried out for the Shijiao-Huangshan intrusive rocks from Zhuji area of Zhejiang Province, which is also tectonically adjacent to the Jiangshan-Shaoxing fault of eastern Jiangnan orogen. The dating results indicate that the Shijiao amphibole pyroxenite and Huangshan quartz diorites were crystallized at 844±3 Ma and 818±6 Ma, respectively, suggesting that they, including the Shijiao orbicular perknites, were probably formed in different periods. Combined with other new available dating results, the authors hold that the Neoproterozoic diorites along the Jiangshan-Shaoxing fault might have been formed during the span of ca. 930-810 Ma. Further studies of the petrology and petrogenesis of the ultramafic rocks and diorites will shed light on the Neoproterozoic amalgamation processes between the Yangtze and Cathaysia blocks.

       

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