【作者】 祝向平；

【导师】 莫宣学； Noel C.White；

【作者基本信息】 中国地质大学（北京） ， 矿物学、岩石学、矿床学， 2010， 博士

【摘要】 哈播斑岩铜(-钼-金)矿床位于哀牢山-红河新生代成矿带南端西侧。矿床内有四期斑岩侵入到哈播南山花岗岩中,依次为黑云母石英二长斑岩、石英二长斑岩、二长斑岩和晚期闪长玢岩。哈播斑岩矿床由蚀变中心发育强钾长石化和黑云母化,伴生石英网脉,晚期绢英岩化广泛发育并叠加早期钾化,Cu-Au矿化主要以石英+黄铜矿脉产出,分布在钾化带外侧,伴生Mo矿化多以石英+辉钼矿脉发育于Cu-Au矿体外缘。辉钼矿Re-Os年龄显示,哈播矿床的成矿年龄为35.47±0.16Ma。哈播南山花岗岩和四期斑岩都有富钾,轻稀土元素明显富集,重稀土元素显著亏损,富集等大离子亲石元素,相对亏损高场强元素等特征,岩浆岩初始(87Sr/86Sr)t值为0.70665～0.70831,εNd(t)均为负值(-5.3 ~ -2.5),表明EH花岗岩和各期斑岩可能具有相似的来源。采用LA-ICP-MS锆石U-Pb年龄测定哈播南山花岗岩、黑云母石英二长斑岩和二长斑岩的加权平均年龄分别为35.37±0.48 Ma、36.20±0.20 Ma和36.19±0.22 Ma,三个样品的锆石结晶年龄一致指示哈播矿床成岩年龄集中于36 Ma,哈播矿床成岩-成矿是一个持续的过程。哈播矿床脉演化序列为早期石英脉→石英+黄铜矿脉→石英+辉钼矿脉。石英脉阴极发光照相结果表明各期脉均有后期热液叠加。脉中流体包裹体的岩相学、体测温和激光拉曼光谱分析等方面研究结果显示,哈播矿床各期脉中流体包裹体均有富气相包裹体、富液相包裹体、气相包裹体和含子矿物三相包裹体,局部偶见CO2三相包裹体;其中各种包裹体中气相均有含CO2、SO2、H2O等气体。各期脉中多种包裹体并存并具有相似的均一温度范围,表明三期脉中流体均发生了“二次沸腾”。推测哈播矿床初始成矿流体是稳定共存、不混溶的低盐度流体和高盐度流体,高盐度流体是哈播矿床成矿元素迁移的主要载体。成矿流体在400℃左右发生“二次沸腾”、分相,温度下降和挥发份持续逃逸可能是Cu-Au成矿的诱因。Mo元素在成矿流体多次沸腾、分相过程中持续优先分配进高盐度流体中而逐步富集;温度下降,含钼硫化物在流体中溶解度降低而沉淀,从而形成石英+辉钼矿±黄铜矿脉。起源于下地壳的富碱岩浆沿断裂-欧梅断裂脉动侵位,形成黑云母石英二长斑岩、石英二长斑岩、二长斑岩等,岩浆上侵、结晶过程发生“一次沸腾”出溶的流体和浆房分异出的流体可能是形成哈播矿床初始成矿流体。初始流体在运移到较浅部位,由于压力降低,发生多次的“二次沸腾”,流体发生分相,并与围岩发生反应,依次形成钾长石化、黑云母化、绿泥石化、绢英岩化,伴生Cu-Au和Mo矿化,是哈播矿床形成的一种可能的机制。更多还原

【Abstract】 Habo porphyry Cu (-Mo-Au) deposit is located in the southwest of the Ailaoshan-Red River Cenozoic metallogenic belt. The Habo intrusive complex is divided into the Pingshan Granite, the Sandaoban Granite, the Ashu Granite and the Habo South Granite. Following emplacement of these granites bodies, four stages of porphyries, ie. biotie-quartz monznite porphyry, quartz-monzonite porphyry,monzonite porphyry and later diorite porphyry occurring as pipes, were intruded into Habo South Granite. Intense feldspathic alteration and biotitic alteration associated by quartz storckwork occur in the Habo deposit alteration center, which is surrounded and overprinted by later feldspar destructive alteration. Cu-Au mineralization mainly occurs as quartz-chalcopyrite veinlets in the outer part of potassic alteration zone, and Mo mineralization occurring mainly as quartz-molybdenite veinlets, is mixed with Cu-Au mineralization but a little far away to the alteration center. The molybdenum mineralization age at Habo is 35.47±0.16Ma, determined by the Re-Os method by LA-ICPMS.Geochemically, the Habo South Granite and four stages of porphyries are all enriched in potassium, enriched in large-ion lithophile elements (eg. K, Rb, Sr, Ba,Th, La) and light rare earth elements, depleted in high field-strength elements and heavy rare earth elements, with relative hagh (87Sr/86Sr)t (0.70665～0.70831) and negativeεNd(t)( -5.3 ~ -2.5),similar to ore-bearing porphyries in Jianshajiang– Ailaoshan alkaline-rich porphyries belt in Eastern Tibet. Zircons selected from Habo South granite, biotite-quartz-monzonite porphyry and quartz-monzonite porphyry were analysed using the LA-ICPMS U-Pb method and gave ages at 35.37±0.48 Ma, 36.20±0.20 Ma and 36.19±0.22 Ma respectively. The similar mineralization age and rock-forming ages suggest that the magmatism and mineralization was a continuous process, and similar to the process at the Yulong porphyry copper deposit.Several stages of veinlets can be observed, and the evolution sequence of vein types is magnetite-quartz veinlets→early quartz veinlets→quartz-chalcopyrite veinlets→quartz-molybdenite veinlets→quartz-sericite-pyrite veinlets→pyrite-chalcopyrite veinlets. Early quartz, quartz-chalcopyrite and quartz-molybdenite veinlets were selected to perform fluid inclusions research. The Cathodoluminescence images of early quartz, quartz-chalcopyrite and quartz-molybdenite veinlets indicate that all were overprinted by later hydrothermal fluids. Vapor inclusions, vapor-rich inclusions, liquid-rich inclusions, and brine inclusions were found in all three types of veinlets, and CO2-bearing inclusions were found locally. Using Laser Raman analysis, we found that CO2 and SO2 are very abundant in all these inclusions. The coexistence of these several types of fluid inclusions with similar homogenization temperature ranges, and some brine inclusions homogenizing by the simultaneous disappearance of vapor and halite, indicate that all these fluids recorded by these three types of veins experienced“secondary boiling”.Vapor-rich and brine inclusions are abundant in early quartz veins, and their homogenization temperatures are similar, which shows that in the Habo deposit the silicate melt directly exsolved two coexisting fluid phases, a vapor and a hypersaline liquid, and the hypersaline fluid is the main carrier of metals. When the fluids migrated upward, at the temperature of ~400°C, the hypersaline liquid entered the two-phase separation field, causing intense boiling and phase separation. With the vapor fluids escaping, the solubility of Cu-Au in the hypersaline fluid decreased, accompanied by intense Cu-Au mineralization. Mo was partitioned into hypersaline fluid during the whole fluid evolution and enriched gradually. On progressive cooling and boiling, the solubility of both Mo and silicates decrease, which is accounted for Mo saturation and deposition.The ore-forming mechanism in Habo should be as the following. Alkaline-rich magma which generated from lower crust intruded along Oumei faults, and formed biotite-quartz-monzontie porphyry, quartz- monzonite porphyry, monzonite porphyry and the later diorite porphyrite. During the intruding and crystallizing process, hydrothermal fluid that exsolved from alkaline-rich magma by“first boiling”, mixed with fluid generated from magma chamber, and comprised the initial metal-bearing fluid in Habo porphyry deposit. On cooling and uplifting, the initial fluid kept on experiencing“secondary boiling”, and reacted with these host rocks, producing K-feldspathic alterantion, biotitic alteration, chloritic alteration and phyllic alteration, associated by Cu-Au mineralization and Mo mineralization.更多还原