云南宾川白象厂金矿床富碱斑岩岩石学特征及找矿预测

发布时间：2018-02-21 15:37

本文关键词： 富碱斑岩岩石学特征白象厂含矿性　出处：《昆明理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：研究区地处我国扬子地台西缘富碱斑岩带内,成矿受哀牢山深大断裂与程海-宾川大断裂两大断裂控制,空间上与北衙金矿床和马厂箐铜钼金矿床等斑岩矿床同属一个成矿带,成矿地质条件优越。本文以白象厂金矿床为研究对象,针对富碱斑岩开展野外地质填图、取样、室内岩矿鉴定、电子探针分析、高精度测试分析和锆石U-Pb测年等研究工作,对研究区富碱斑岩的岩石学特征进行系统研究,对富碱岩体及其含矿性进行了重点剖析,确定了该矿床富碱岩体为成矿岩体,并取得以下认识:①研究区富碱斑岩为浅成-超浅成相岩株(岩脉、岩枝),岩石类型以二长斑岩为主。矿物成分有透长石、斜长石、角闪石和黑云母等。②研究区富碱斑岩为中酸性岩类,具有SiO2过饱和、富碱高钾、高铝、类A型花岗岩特征;铝饱和指数A/NKC表明研究区斑岩属于准铝质到过铝质过渡的岩石;白象厂富碱斑岩微量元素具有明显的Rb、Sr、Ba、Th、U、K等大离子亲石元素相对富集,而Ta、Nb、Ce、P、Ti等高场强元素相对亏损的特征;稀土元素球粒陨石标准配分曲线显示出轻稀土富集,重稀土亏损的右倾平滑曲线特征,其还具有微弱的铕负异常。③由U-Pb同位素测年结果可知,本文所测的15个锆石测点显示的206Pb/238U表面年龄在33.8～37.8Ma范围内,但由于“幕式铅丢失”,谐和曲线上交点最终确定研究区富碱斑岩的成岩年龄为34.4Ma,属喜马拉雅早期。④从花岗岩类微量元素构造环境判别图解和R1-R2因子构造环境判别图解显示研究区富碱斑岩产出于后碰撞的拉伸环境。研究区富碱斑岩来源于经地幔派生的壳幔混合区,为张性构造环境下幔源岩浆活动的产物。⑤研究区富碱斑岩是含矿岩体,含有金、银、铜、铅、锌等多金属组合矿化。结合研究区岩体地质特征、岩石化学特征、物化探资料分析,显示白象厂富碱斑岩具备找到斑岩型矿床的有利前景。研究认为该区富碱斑岩体内、岩体与围岩内外接触带、深部隐伏斑岩体内具有找到较大工业型斑岩矿床的巨大潜力,值得进一步挖掘。
[Abstract]:The study area is located in the alkali-rich porphyry belt on the western margin of the Yangtze platform in China. The mineralization is controlled by the two major faults of Ailaoshan deep fault and Chenghai-Binchuan fault, and belongs to the same metallogenic belt as the Beiya gold deposit and the Machangqing copper-molybdenum gold deposit in space. The ore-forming geological conditions are superior. In this paper, taking the Baichang gold deposit as the research object, field geological mapping, sampling, indoor rock ore identification, electron probe analysis, high-precision test analysis and zircon U-Pb dating are carried out for alkali rich porphyry. The petrological characteristics of alkali-rich porphyry in the study area are systematically studied, and the alkali-rich rock mass and its ore-bearing properties are emphatically analyzed, and the alkali-rich rock mass of the deposit is determined to be ore-forming rock mass. The following conclusions have been obtained that the alkali-rich porphyry in the study area is epigenetic and ultra-shallow facies (vein, branching, rock type, mainly monzomorphic porphyry). The mineral composition of the porphyry is permeable feldspar, plagioclase, plagioclase, plagioclase, etc. The alkali-rich porphyry rocks in the study areas such as amphibole and biotite are intermediate-acidic, characterized by SiO2 supersaturation, high alkali and high potassium, high aluminum and A-like granites, and the Al saturation index A / NKC indicates that the porphyry in the study area belongs to the transition from quasi-aluminite to peraluminous. The trace elements in the alkali rich porphyry rocks in Bishangchang are characterized by the relative enrichment of large ion lithophile elements, such as RbBX, SrBX, Bajiu, UK, and so on, while the relative depletion of high field strength elements, such as Tahln, NbCe, Pu, Ti, etc. The standard distribution curve of chondrites of rare earth elements shows the enrichment of light rare earths. The characteristics of the right-dip smoothing curve of heavy rare earth depletion and the weak europium negative anomaly .3 from U-Pb isotopic dating indicate that the surface age of 206 Pb / 238U measured at 15 zircon sites in this paper is in the range of 33.837. 8 Ma. However, due to the "curtain lead loss", the diagenetic age of the alkali-rich porphyry in the study area was determined to be 34.4Ma. the diagenetic age of the alkali-rich porphyry in the study area was determined by the intersection point of the harmonic curve. The diagram shows that the alkali-rich porphyry occurred in the post-collisional extensional environment. The alkali-rich porphyry originated from the crust and mantle mixed region derived from the mantle. The alkali-rich porphyry in the study area is ore-bearing rock mass, which contains gold, silver, copper, lead, zinc and other polymetallic assemblages, combined with the geological characteristics and petrochemical characteristics of the studied area, which is the product of mantle-derived magmatic activity in the tensional tectonic environment. The analysis of geophysical and geochemical data shows that the bishangchang alkali-rich porphyry has a favorable prospect of finding porphyry type deposits. It is considered that there is a contact zone between rock mass and surrounding rock inside and outside the alkali-rich porphyry in this area. The deep concealed porphyry body has great potential to find large industrial porphyry deposits, which is worth further excavating.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P618.51

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