a.中国地质调查局成都地质调查中心,成都理工大学,四川里伍铜业有限公司,a.中国地质调查局成都地质调查中心
Chengdu Center, China Geological Survey,Chengdu University of Technology,Sichuan Liwu copper limited company,Chengdu Center, China Geological Survey
西藏冈底斯成矿带南缘西段新发现的朱诺铜矿床是具有大型规模的斑岩铜钼矿床。金红石是斑岩铜矿床中最典型的副矿物之一，对其成分和结构特征的研究能反演成矿流体演化过程并确定斑岩铜矿的主矿体。在详细的野外地质观察的基础上，对钾化带成矿斑岩(黑云花岗闪长岩)中金红石的研究表明：金红石主要与磁铁矿(Ⅰ类)、赤铁矿共生(Ⅲ类)，常形成固溶体分离结构并分布在黑云母裂隙及附近；其次呈板状(长10~80μm, 宽3~10μm)、颗粒状(粒径10~40μm)、不规则状独立分布在石英硫化物脉中(Ⅱ类)。Ⅰ类金红石是由钛磁铁矿在富S条件下反应形成的；Ⅲ类金红石由钛铁矿在富氧条件下反应形成的；Ⅱ类金红石是由含Ti的热液结晶沉淀而来的。成矿斑岩全岩中TiO2的含量为 0.66%，为金红石的形成提供了丰富的物源。成矿斑岩金红石中的电子探针分析结果显示，其成分除含有约94%的TiO2外，还含有V2O3，Nb2O5，FeO，WO3，CaO，SiO2，Al2O3，ZrO2，几乎不含或很少含MgO和MgO。金红石中V2O3范围为0.20%~2.39%，平均为0.49%， Nb.2O5的含量范围为0.20%~4.63%，平均1.25%，WO3和FeO的平均含量分别为1.92%和1.81%，且有约0.05%的ZrO2异常。利用金红石找矿方法开展朱诺矿床外围找矿时，首先必须考虑金红石中V2O3的含量(＞0.2%，Ⅱ类金红石＞ 0.5%)，在此基础上考虑Nb的含量(＞0.2%，乙类金红石＞2.6%)，同时考虑W，Fe偏高，Zr异常的特点。对Ⅱ类金红石还需要额外考虑其粒径大于10μm。
Zhunuo porphyry deposit, newly discovered in the west of southern Gangdase metallgoenic belt, Tibet, is a typical porphyrytype CuMo deposit with a very large Cu reserves. Rutile is one of the typical accessory minerals for porphyry copper deposits. Therefore, its composition and texture can deduce the evolution process of oreforming fluids and determine the main orebodies. Based on detailed field geological work, metallogenic porphyry (biotite granodiorite) samples from the potassic alteration zone were studied. The results indicate that the rutiles usually coexist with magnetite (Ⅰ kind) and hematite (Ⅲ kind), both of which occur in and around biotites. Striped (long10~0 μm, with 3~10 μm), granular (diameter 10~40 μm), or irregular rutiles occur within quartzpyrite veins (Ⅱ kind). The three occurrences of rutiles formed in three conditions: the I kind of rutiles was formed by the reaction of titanic magnetite under the condition of Srich environment during or after the alteration of biotite or titanite; the Ⅱ kind of rutiles was formed by reaction of ilmenite in the Orich environment during or after the alteration of biotite or titanite; and the Ⅲ kind of rutiles directly precipitated from the Tibearing fluid. The metallogenic porphyry has the high concentration (066 wt.%) of TiO2, which provided abundant oreforming material source. Electron microscope analyses show that rutiles are dominantly TiO2 of 94%, but relatively enriched in V2O3，Nb2O5，FeO，WO3，CaO，SiO2，Al2O3 and ZrO2, with few or without MgO and MgO The compositions of V2O3 and Nb2O.5 range from 020 ot 2.39 wt % (with an average of 0.49 wt%) and from 0.20 to 4.63 wt%( with an average of 1.25 wt%) respectively. And average compositions of WO3 and FeO are 192 wt% and 181 wt % respectively, with about 005wt.% of ZrO2 in rutiles. When carrying out exploration outside the Zhunou deposit using rutiles, the first consideration should be the composition of V2O3 in retiles above 02wt.% （Ⅱ kind should be above 05 wt.%), and then the composition of Nb2O5 should be considered above 02 wt.% (Ⅲ kind of retiles should above 26 wt.%) . And the high concentration of W，Fe , the anomaly of Zr should also be considered. Furthermore, the grain size of the Ⅱ kind of rutiles should be above 10 μm.
戴婕,倪师军,黄勇,丁俊,周义明.2018.西藏朱诺斑岩型Cu-Mo矿床成矿斑岩金红石成因及找矿指示意义[J].地质学报,92(6):1228-1239.
DAI Jie, NI Shijun, HUANG Yong, DING Jun, Chou I-Ming.2018. Genesis of Rutile from Metallogenic Porphyry in the Zhunuo Porphyry-type Cu-Mo Deposit, Tibet, China, and Its Significance for Prospecting[J]. Acta Geologica Sinica,92(6):1228-1239.
