西准噶尔托里县都伦河东岩体锆石U-Pb年龄及地质意义

西准噶尔地体晚古生代岩浆活动强烈, 其中以达尔布特构造-岩浆带最为显著。近年来, 对该带大岩基研究较多, 而对该带小岩体的研究主要集中在包古图一带成矿斑岩上, 对其余小岩体研究较为局限。位于西准噶尔托里县的都伦河东岩体内外接触带有较强的孔雀石化、硅化、碳酸盐化、绿泥石化、黄铁矿化等蚀变与矿化, 岩体内部发育镁铁质微粒包体。本次于寄主石英闪长岩中获得(312.6±4.2)Ma(n=21, MSWD=0.15, 95%置信度)的LA-ICP-MS锆石U-Pb年龄, 其与包古图小岩体(Au-Cu矿化)和夏尔莆小岩体(Cu-Mo矿化)的成岩时代基本一致, 各岩体形成的构造环境大致相同。该可靠年龄为研究本区与小岩体有关, 与岩浆混合作用有关的Au-Cu-Mo成矿作用时代提供了年代学约束。

Zircon U-Pb Age and Geological Significance of Dulunhe Granite in Tuoli,Western Junggar

There are large numbers of intrusive granites exposed along the Daerbute tectonic-magmatic belt in the center of western Junggar. Many researches have been conducted on the batholites instead of small granite intrusions, which mainly distributed in porphyry mineralization belt of the Baogutu region. Wallrock alterations such as malachitization, silicification, carbonatization, chloritization and pyritization are well developed in Dulunhe granite, which is located in Kuoyitasi area of Zayier Mountain, and abundant mafic microgranular enclaves can be found in these host rocks, however, accurate geochronology data is still insufficient. High-precision LA-ICP-MS zircon U-Pb dating reveals that the quartz diorite in the Dulunhe granite is formed at (312.6±4.2)Ma(n=21, MSWD=0.15, 95% confidence degrees) in early late Carboniferous. Combined with previous researches, the authors suggest that the age of Dulunhe granite is consistent with small granites like Baogutu granite (Au-Cu mineralization) and Xiaerpu granite (Cu-Mo mineralization); both of them are probably formed in the subduction-related setting. This reliable age provides chronology constraints for the study of regional mineralization age that related to small granite and magma mixing of Au-Cu-Mo deposit.