新疆北部岩浆铜镍硫化物矿床地质分布特点与成矿背景探讨
Geological Distribution Characteristics and Metallogenic Background of Magmatic Ni-Cu Sulfide Deposits in the North Part of Xinjiang
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摘要: 新疆北部地质构造演化复杂, 多阶段演化中岩浆活动与成矿作用规模并不均衡。而二叠纪却是天山成矿带大规模岩浆活动和金属成矿作用的高爆发期。本研究紧紧围绕镁铁-超镁铁质侵入岩体及岩浆铜镍硫化物矿床, 从地质分布特点、含矿岩体的岩浆起源、岩浆演化及成矿特点, 系统研究深部相应岩浆作用的地质背景。通过典型矿床的深入剖析, 破解制约找矿突破的控制因素, 系统阐述了板块构造与地幔柱体制叠加并存的地质特征与成矿表现。新疆北部发育了5条镁铁-超镁铁质侵入岩带, 东天山、北山及喀拉通克岩带具有较好的成矿表现, 在时间上与塔里木隐伏大火成岩省密切相关。塔里木克拉通深部熔融的地幔物质, 围绕刚性塔里木克拉通边缘不断上涌, 并与表壳物质发生交换, 随着俯冲板块的持续和减弱, 深部上涌的地幔物质不断加强, 先后形成因深部地幔物质多寡而金属聚集的不同矿床类型。围绕塔里木大火成岩省的周缘或造山带中, 是岩浆铜镍硫化物矿床重要的理论研究基地和找矿方向。Abstract: Geological tectonic evolution is complicated in the north of Xinjiang and its magmatism and mineralization was disequilibrium among multi-stage evolutions. The period of Permian was high outbreak stage on large-scale magmatism and mineralization. This study focused on mafic-ultramafic intrusions and magmatic Ni-Cu sulfide deposits, and researched metallogenic background and geological process of deep magma activation through geological distribution characteristics of mafic-ultramafic intrusions, magma origin, magma evolution and mineralization characteristics of ore-bearing intrusions. By in-depth analysis of typical deposit, controlling factors that restricted prospecting were found out, geological characteristics and mineralization features of tectonic system coexistence of plate and mantle plume were systematically expounded. There were 5 mafic-ultramafic intrusion belts in north Xinjiang, and east Tianshan, Beishan and Kalatongke belts formed many magmatic Ni-Cu sulfide deposits related to mafic-ultramafic intrusions and large igneous province in time. The melt mantle material from the deep of Tarim craton upwells along the margin of rigid Tarim craton, and exchanges with supracrustal material. The deep mantle material strengthened constantly with sustainable weakened subduction, finally, different ore deposits were formed respectively because of deep mantle material content. Periphery or orogenic belts circling Tarim large igneous province is important direction for ore-formation theory study and prospecting of magmatic Ni-Cu sulfide deposits.