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    甘肃北山孙家岭含钪岩体LA-ICP-MS锆石U-Pb测年及地质意义

    LA-ICP-MS zircon U-Pb dating and geological significance of the Sunjialing scandium mineralized intrusion in the Beishan region, Gansu Province

    • 摘要: 孙家岭含钪岩体位于哈萨克斯坦板块中星星峡—明水—旱山微板块的雅满苏—红石山—黑鹰山晚古生代裂谷带。岩体侵位于下石炭统白山组,由含斜长石角闪石岩和角闪石岩组成,钪主要赋存于角闪石矿物中。含钪岩体属富铁质超基性岩,全岩成分以高碱、高铝为特征;稀土含量较高,轻稀土略富集,具有明显的负Eu异常;大离子亲石元素(LILE)K、Rb、Ba、Sr、U富集,相对亏损高场强元素(HFSE)Nb、Zr、Hf、Th及P。通过LA-MC-ICP-MS锆石U-Pb测年,首次获得孙家岭含钪岩体中角闪石岩形成于(339.5±2.6)Ma,表明该含矿岩体侵位及矿化作用发生于早石炭世,为裂谷拉张环境下伸展作用的产物。

       

      Abstract: Located in the Yamansu-Hongshishan-Heiyingshan Late Paleozoic rift of Xingxingxia-Mingshui-Hanshan microplate in Kazakhstan plate, the Sunjialing scandium mineralized intrusion emplaced in the Early Carboniferous Baishan Formation and consists of plagioclase amphiboles and amphiboles, with scandium mainly occurring in the amphibole. Scandium mineralized intrusion belongs to iron-rich ultrabasic intrusion, whose components are characterized by high alkali and alumina. The content of rare earth is high, and the light rare earth is slightly enriched, with obvious negative δ (Eu) anomaly. LILE elements Rb, Ba, Sr and U are enriched whereas HFSE elements Nb, Zr, Hf, Th, and P, Ti are depleted. LA-MC-ICP-MS zircon U-Pb dating of the hornblende yielded an age of (339.5 ±2.6)Ma, which suggests that both the intrusion of the ore-bearing complex and the mineralization occurred in early Carboniferous in a rift environment.

       

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