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雄村斑岩型铜金矿集区位于西藏冈底斯成矿带,是目前该带上发现的唯一一个与新特提斯洋壳早期俯冲作用有关的斑岩型铜金矿区,由Ⅰ、Ⅱ、Ⅲ号铜金矿体组成。雄村Ⅰ号铜金矿体具有规模大、蚀变强烈、富金银而贫钼的特点,其蚀变-矿化系统受中-晚侏罗世侵入于雄村组凝灰岩中的多个含眼球状石英斑晶的角闪石英闪长玢岩岩枝的控制,矿体即赋存于玢岩岩枝及其接触带附近的凝灰岩中。通过对雄村Ⅰ号铜金矿体蚀变和矿化特征的研究可以得出以下几点认识:①Ⅰ号铜金矿体的热液蚀变作用可分为早、晚2期,早期蚀变经历了弱的钾硅酸盐化阶段和强烈红柱石次生石英岩化阶段,晚期蚀变经历了黄铁绢英岩化阶段和青磐岩化阶段,晚期蚀变叠加于早期蚀变之上。由斑岩体中心向外,蚀变分带依次可划分为强硅化带→红柱石次生石英岩化带→绢英岩化带→青磐岩化带。主要赋矿蚀变带为强硅化带和红柱石次生石英岩化带。②Ⅰ号铜金矿体的矿化主要呈浸染状、脉状或网脉状。由斑岩体中心向外,矿化分带依次为黄铁矿-黄铜矿-(磁黄铁矿)→黄铁矿-磁黄铁矿-(黄铜矿)→黄铁矿→闪锌矿,主要含矿脉的分布依次为石英-硫化物脉→石英-红柱石-黑云母(白云母)-硫化物脉→黄铁矿脉→多金属硫化物脉,主要赋矿脉为石英-硫化物脉和石英-红柱石-黑云母(白云母)-硫化物脉。③Ⅰ号铜金矿体弱的钾硅酸盐化蚀变和强烈的红柱石次生石英岩化蚀变暗示成矿流体具有较低的K+/H+值。在斑岩蚀变系统形成早期,矿床经历了高温阶段,形成弱的钾硅酸盐化蚀变,之后,斑岩蚀变系统迅速降温,形成大规模的红柱石次生石英岩化蚀变,斑岩蚀变系统的早期迅速降温可能是由于岩体的上侵导致表层岩石引张而产生断裂破碎,使得大气降水能快速的进入斑岩蚀变系统而造成的。
The Xiongcun porphyry copper-gold deposit is located in the Gangdese metallogenic belt of Tibet and is the only porphyry-type copper-gold deposit associated with the early subduction of the Neo-Tethys oceanic crust. It consists of Ⅰ , Ⅱ, Ⅲ copper and gold ore body composition. The Xiongcun No.1 copper-gold orebody has the features of large scale, strong alteration, rich gold and silver, and poor molybdenum. The alteration-mineralization system is affected by Middle-Late Jurassic intrusions in the Tuocun Formation The control of the amphibole quartz diorite porphyrite in the ocular quartz porphyrite is that the orebodies occur in the tuffs of the diorite rock and its contact zone. Through the study on the alteration and mineralization of the Xiongcun No.1 copper-gold ore body, we can draw the following conclusions: ① The hydrothermal alteration of the No.1 copper-gold ore body can be divided into two phases of early and late alteration After experiencing weak potassium-silicification stage and strong andalusite secondary quartzization stage, the late alteration underwent the yellow-iron-silite-stage and the epidote stage. Late alteration superimposed on the early alteration. From the center of porphyry to the outside, the alteration zonation can be divided into strong silicification zone → isoprotectic quartzite → sericite lithotripsy → igneous rock zone. The main ore-forming altered zones are strongly silicified zones and andalusite secondary quartzitic zones. The mineralization of No.1 copper-gold ore body is mainly disseminated, veins or reticulate. From the center of porphyry to the outside, the mineralization zoning is pyrite - chalcopyrite - (pyrrhotite) → pyrite - pyrrhotite (chalcopyrite) → pyrite → zinc oxide The distribution of the main ore-bearing veins is in turn quartz-sulfide veins → quartz-andalus-biotite (muscovite) -sulphide veins → pyrite veins → polymetallic veins, and the main veins are quartz-sulfide Veins and quartz - andalusite - biotite (muscovite) - sulfide veins. ③ Weak potassium-silicate alteration of I-type copper-gold ore body and strong alteration of andalusite secondary quartz suggest that ore-forming fluids have lower K + / H + values. In the early stage of the porphyry alteration system, the ore deposit underwent a high temperature stage and formed a weak potassium-silicate alteration. After that, the porphyry alteration system rapidly cooled to form a large-scale andalusitic alteration of quartz, The early rapid cooling of the porphyry alteration system may be caused by the rock intrusion leading to the extension of the surface rock to cause fracture and fracture, so that the atmospheric precipitation can rapidly enter the porphyry alteration system.