大兴安岭潮满林场地区新元古代花岗质片麻岩——锆石U-Pb测年、地球化学特征及构造环境探讨

THE NEOPROTEROZOIC GRANITIC GNEISS IN CHAOMAN FOREST FARM AREA OF DAXINGANLING MOUNTAINS: Zircon U-Pb Dating, Geochemistry and Tectonic Environment

摘要: 对大兴安岭潮满林场地区新元古代花岗质片麻岩进行岩石学、地球化学、成因及构造环境研究结果显示，花岗质片麻岩年龄为795.2±4.3 Ma，形成时代为新元古代. 花岗质片麻岩表现为高硅、高碱、富钙、富钠、富钾、轻稀土元素富集、重稀土元素亏损，Eu为负异常弱亏损. 岩浆源区主要为壳源岩浆，部分幔源岩浆底侵使中下地壳岩石发生部分熔融，且受到幔源组分混染形成混合岩浆. 结合区域资料，研究区新元古代花岗片麻岩形成于与俯冲有关的岩浆弧环境.

Abstract: The study on the petrology, geochemistry, genesis and tectonic environment of Neoproterozoic granitic gneiss in Chaoman Forest Farm area of Daxinganling Mountains yields the age of 795.2±4.3 Ma. The granitic gneiss is characterized by high Si, high alkali, rich Ca, Na and K, enrichment of LREEs and depletion of HREEs, with weak negative Eu anomaly and depletion. The magma source area is mainly crust-derived magma, and some mantle-derived magma underplating causes partial melting of rocks in the middle-lower crust, with hybridization of mantle-derived components to form mixed magma. Combined with regional data, the Neoproterozoic granitic gneiss in the study area was formed in a magmatic arc environment related to subduction.