【作者】 钟裕锋；

【导师】 唐菊兴； 钟康惠；

【作者基本信息】 成都理工大学 ， 矿物学、岩石学、矿床学， 2011， 硕士

【摘要】 西藏墨竹工卡县甲玛铜多金属矿床位于青藏高原冈底斯成矿带中南部,是目前西藏最具有经济价值的超大型铜多金属矿床之一。该矿床不仅规模巨大,而且除主元素铜、钼达到超大型外,其他有用组分金、银、铅锌均达到大型规模。本文通过对金的赋存状态进行研究,将有助于资源的合理利用,提高矿床的经济价值,也将有助于我们了解为什么甲玛铜多金属矿有别于冈底斯成矿带其它中新世斑岩铜矿,富含金等成矿元素。在冈底斯成矿带,像甲玛这样矿体规模巨大、矿石类型复杂、成矿元素丰富、富矿体厚度大的斑岩-矽卡岩型矿床实属罕见。而且,在主矿体的边部已发现石英闪长玢岩型的独立金矿体,因此,研究矿石中金的赋存状态意义重大。论文在广泛收集资料、野外地质调查和钻孔编录的基础上,通过对岩矿石样品的采集、基本化学样品的分析数据的处理、镜下光薄片鉴定、电子探针测试(黄铁矿、黄铜矿、斑铜矿、自然金为主)和电镜扫描等方面的研究,初步掌握了甲玛含金矽卡岩型矿石的地质特征、金的分布规律、金的运移沉淀和赋存状态并取得了如下认识:通过野外调查、剖面测制、平硐编录、岩矿鉴定、分析测试等工作,确定甲玛矿床属于斑岩型-矽卡岩型铜多金属矿,矿石中金的含量较高,平均品位约0.33g/t,最高可达98.7g/t,伴生金一般富集于矽卡岩中的含铜矿石。而在角岩型矿体、斑岩型矿体中含量则很低,总体达不到伴生有用组分的含量。主要富金矿石位于矿区的东北部ZK025附近,垂向分布于海拔4280～4550m之间的矽卡岩铜钼矿体中。通过组合分析发现,矿床中金与铜存在明显的正相关关系,其次是银,而金与其它元素间的相关性较差。矿体中的金的赋存状态主要有以下几种方式:一、以自然金的方式产于斑铜矿的裂隙中,部分产于石英裂隙中;二、以自然金和银金矿的方式产于闪锌矿和斑铜矿的矿物颗粒之间;三、以自然金和银金矿的形式产于斑铜矿和黄铜矿的边缘,形成连生金结构;四、以自然金和银金矿的形式包裹于多金属硫化物中,其中黄铜矿和斑铜矿是包裹金的主要载体。此外,在矿区的脉石矿物中还发现有自形粒度的铜金矿和含金自然银。金的粒度较小,属于显微金,大部分金在0.06～0.0002 mm之间,在选冶过程中需要将矿石磨至0.06mm以下,有利于金的充分回收。由于独立金矿体的金主要赋存于黄铁矿和毒砂中,因此在选冶过程中应区别处理。更多还原

【Abstract】 Jiama copper-polymetallic deposit in Mozhugongka county of Tibet is located in the south-central Gangdise ore belt of Tibetan Plateau.And it is one of the most economic value of ultra-large type copper-polymetallic deposits. The deposit is not only huge in the scale, but also many main elements like copper and molybdenum reach the ultra-large type and except these two elements, other useful components such as gold, silver, lead and zinc all achieve a large scale. Based on the studying of gold’occurrence state, it will contribute to make good use of resources and improve the economic value of deposits, and it will also help us understand why Jiama copper polymetallic is different from other Gangdese Miocene porphyry copper deposits, riched in gold and other ore-forming elements.In the Gangdese metallogenic belt, it is very rare to see such huge orebody like Jiama deposite. It is huge, of complexe ore types and of rich ore-forming elements, and it belongs to porphyry– skarn deposite of high-grade ore body thickness. Moreover, at the margin of the main ore body, we have found independent gold of quartz diorite porphyry type, and therefore the study of the occurrence of gold in ore is of great significance.The discourse is on the basis of wide collecting predecessor’s information, geological survey and drill core logging. And brings to success by ore samples collection, processing of the basic chemical analysis data of ore samples, identification of the polished thin section under the microscopy, electron probe microanalyser (pyrite, Copper, bornite, native gold-based) and scanning electron microscopy. Through those methods above, we have a preliminary grasp of the Jiama auriferous skarn-type ore geological features, the distribution and the precipitation process of gold’s occurrences and migration. Finally, we achieved the following understanding:Through field investigation, profile measurement system, adit logging, rock and mineral identification, analysis and testing, it is ascertained to figure out that Jiama deposit is a porphyry - skarn copper-polymetallic ore. It has a high content of gold in ore, with an average grade of about 0.33g / t, the highest being 98.7g / t, and associated gold generally enriches in the copper-bearing ore of skarn. However, associated gold is in the condition of low content in hornstone orebody and porphyry orebody, which in general doesn’t reach of the content of useful components associated. The gold rich ore is mainly located near the northeast ZK025 of the mining area, and vertically distributes in skarn copper-molybdenum ore body at an altitude of between 4280 ~ 4550 meters. Through a combination of analysis, gold and copper of the deposits is in the obvious positive correlation, and so is gold and sliver. While the correlation of gold and other elements is poor.The occurrence state of gold in orebody mainly has the following ways: firstly, Au appears in fracture of bornite in the form of native gold or it is partly wrapped in cracks of quartz; Secondly, Au presents among mineral particles of sphalerite and bornite in the way of native gold and electrum; Thirdly, Au produces at the edge of bornite and chalcopyrite in the way of native gold and electrum, forming structure of attachement gold ; Fourthly, Au is wrapped in polymetallic sulfide in the form of native gold and electrum, and chalcopyrite and bornite are the main carriers of inclusion gold. In addition, in the gangue minerals of the mining area, it is also found that there are copper gold and gold-bearing native silver which respectively form grain size of their own.The particle size of gold is relatively small, which belongs to microscopic gold.The size of most gold is among 0.06 ~ 0.0002 mm. In the process of beneficiation and metallurgy, the size of minerals needs grinding to 0.06mm below, which is good for the full recovery of gold. As the independent gold ore bodies mainly occur in pyrite and arsenopyrite, they should be dealt with differently in the process of beneficiation and metallurgy.更多还原