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初步矿产普查评价成果表明,三江北段已初步显示出巨大的成矿潜力。在该区东部,以纳日贡玛-陆日格含矿斑岩体为中心的斑岩-矽卡岩大型成矿系统已初露端倪。纳日贡玛,作为该区的最具代表性的斑岩型矿床,了解其含矿斑岩的性质,查明斑岩的可能源区,厘定其与玉龙铜矿带的关系,具有重要的理论与现实意义。为此,本文对纳日贡玛矿区出露的主要斑岩体开展了详细的年代学、岩石地球化学及 Sr-Nd—Pb 同位素地球化学研究,结果表明:纳日贡玛主含矿斑岩锆石 U-Pb 年龄为43.3±0.5Ma,明显为玉龙斑岩铜矿带的北延;其主含矿斑岩为高钾钙碱性系列,高度演化的斑岩为钾玄岩系列,岩浆源区可能为50～80km 处壳幔过渡带,经历了明显的流体交代;与玉龙铜矿带含矿斑岩相比,纳日贡玛斑岩钾含量偏低,Sr-Nd—Pb同位素组成更向亏损地幔靠拢,反映岩浆源区自 NW 至 SE 地壳组分逐渐增多和/或流体交代逐渐增强。自纳日贡玛至玉龙带,成矿斑岩的结晶年龄逐渐变新,说明斑岩的形成不仅具有统一的源区,可能受控于统一的动力学机制,因印度-亚洲大陆碰撞产生的始新世右行断裂系统,可能是控制区域岩浆上侵及时空分布的动力学机制。纳日贡玛带矿床矿化以 Mo 为主,显著不同于玉龙带的 Cu-Mo(-Au)矿化组合,造成区域上矿化组合的差异即可因深部过程,也可因岩浆就位后的结晶分异过程,更多的证据显示可能受后者控制明显;因此,纳日贡玛矿床可能遭受了较强的剥蚀。区内应加强斑岩侵位较深时形成的斑岩钼矿及夕卡岩型矿床的寻找。
Preliminary mineral census evaluation results show that the northern part of Sanjiang has initially shown a huge potential for mineralization. In the eastern part of the area, a large-scale porphyry-skarn metallogenic system centering on the Najgomma-Luzhug porphyry body has begun to emerge. As the most representative porphyry deposit in the area, knowing the nature of the ore-bearing porphyry, identifying the possible source area of the porphyry, and determining the relationship with the Yulong copper belt, it is of great importance Theoretical and practical significance. For this reason, detailed geochronology, lithogeochemistry and Sr-Nd-Pb isotope geochemistry of the main porphyry bodies exposed in the Nagisa Gongma area have been studied in this paper. The results show that: The zircon U-Pb age is 43.3 ± 0.5Ma, apparently for the northern extension of the Yulong porphyry copper belt; its main porphyry is a high-K calc-alkaline series, the highly evolved porphyry is a series of potashites, The source zone may be the crust-mantle transitional zone at 50 ~ 80km and undergo obvious fluid replacement. Compared with the ore-bearing porphyry in the Yulong copper ore belt, the content of potassium in the Najigon porphyry is low and the Sr-Nd-Pb isotopic composition And moved closer to the depleted mantle, reflecting the gradual increase of crustal components from NW to SE and / or the gradual increase of fluid exchange in the magmatic source area. The crystallization age of the ore-forming porphyries gradually changes from the Nagasongma to the Yulong belt, indicating that the porphyry formation not only has a uniform source region but may be controlled by a unified kinetic mechanism resulting from the collision of the Indo-Asian continent The Eocene right-lateral fault system may be the dynamic mechanism of magmatic intrusion and spatial-temporal distribution in the controlled area. The mineralization of the Nagi Gommar zone is dominated by Mo, which is significantly different from the Cu-Mo (-Au) mineralization assemblage in the Yulong zone, resulting in differences in the mineralization assemblages in the area due to deep processes and magmatic in situ After the crystallization of the differentiation process, more evidence shows that the latter may be obvious control; therefore, the Nagi Gomma deposit may suffer strong erosion. The area should be strengthened porphyry emplacement formed deeper porphyry molybdenum ore and skarn deposits looking for.