光谱学与光谱分析, 2020, 40 (2): 610, 网络出版: 2020-05-12  

广东大宝山多金属矿床断层剖面矿物X射线衍射和近红外光谱分析及其意义

XRD and NIR Analysis on Minerals of Fault Sections from Dabaoshan Polymetallic Deposit, Guangdong
王国强 1,2,3,4,*曹建劲 1,2,3,4邓永康 1,2,3,4刘翔 1,2,3,4
作者单位
1 中山大学地球科学与工程学院, 广东 广州 510275
2 广东省地质过程与矿产资源探查重点实验室, 广东 广州 510275
3 广东省地球动力作用与地质灾害重点实验室, 广东 广州 510275
4 南方海洋科学与工程广东省实验室, 广东 珠海 519082
摘要
大宝山多金属矿床为典型的金属硫化物矿床, 其具有经济价值的成矿元素包括铜、 铁、 铅、 锌、 钨、 钼等。 矿床的成矿作用与岩浆和变质热液蚀变活动有着密切联系。 矿区内构造断裂的广泛发育为成矿热液活动提供了通道和有效的成矿容矿空间, 并在成矿后对矿体可以进行改造作用。 该研究中在大宝山铜多金属矿床的三个断层剖面中, 采集了断层泥、 含矿脉体和蚀变围岩共8个样品。 然后, 对所有样品通过X射线衍射(XRD)和近红外光谱分析(NIR)两种光谱学方法进行了综合测试分析。 在样品中多种蚀变类型矿物组合通过光谱学分析被鉴别出来, 主要包括黄铁绢英岩化矿物组合(石英、 绢云母、 黄铁矿和黄铜矿等)、 矽卡岩化矿物组合(透闪石、 阳起石和石榴石等)和青磐岩化矿物组合(绿泥石、 碳酸盐和黄铁矿等)。 这些蚀变类型的矿物组合的表明矿区的岩石经历了多种热液蚀变作用的叠加。 断层泥样品中则可以鉴别出蚀变围岩和含矿脉体的矿物成分, 以及金属氧化物和硫酸盐矿物(黑铜矿、 铜矾、 钾铁矾和钾明矾石等), 以及粘土矿物(伊利石、 蒙脱石、 高岭石和滑石等)。 断层泥中的氧化和风化矿物指示了断层作用为岩石的物理和化学风化过程提供了有利条件。 此外, 根据三个断层剖面中蚀变围岩的NIR图谱, 计算了白云母类矿物的结晶度参数(IC=Al-OH(2 200 nm)吸收峰强度/H2O(1 900 nm)吸收峰强度)。 在蚀变围岩样品中637平台的IC1=0.078 71/0.037 76≈2.08; 793平台的IC2=0.108 8/0.014 8≈7.35; 817平台的IC3=0.098 6/0.039 1≈2.52。 显然, 793平台蚀变围岩白云母类矿物的结晶度明显高于其他两个平台的样品。 结晶度越高表明热液活动的温度越高, 进而可以推测在793平台蚀变围岩的采样位置相对而言可能更接近于热液活动中心。 综上所述, 将XRD和NIR两种光谱学分析方法相结合有助于快速准确鉴别蚀变矿物的类型和结晶度, 从而为矿床学研究和找矿勘探提供更加丰富的地质资料。
Abstract
The Dabaoshan polymetallic deposit is a typical metal-sulfide deposit, and the metallogenic elements of economic value include copper, iron, lead, zinc, tungsten, molybdenum, etc. Mineralization of the deposit is closely related to magmatic and metamorphic hydrothermal alteration. Faults widely developed in the mining area provide the pathway of hydrothermal ore-forming solution migrating and the available ore-forming space. Moreover, faults can transform ore bodies after mineralization. In this study, 8 samples were collected from three fault sections in Dabaoshan Polymetallic Deposit, and the sample types include fault gouges, ore-bearing veins and altered wall-rocks. Then, all the samples were comprehensively analyzed by XRD analysis method and NIR analysis method. Varity of altered mineral assemblages were identified by spectral analysis, include beresitization (quartz, sericite, pyrite and chalcopyrite, etc), skarnization (Diorite, actinolite, garnet, etc) and propylitization (chlorite, carbonate, pyrite, etc). The altered mineral assemblages indicate that the rocks in mining area had undergone a variety of alteration types. In the fault gouges samples, we can identify minerals of altered wall rock and ore-bearing veins, as well as, the oxidation and weathering products such as metal oxides, sulfates (tenorite, antlerite, krausite and kalunite) and clay minerals (illite, montmorillonite, kaolinite and talc, etc). The oxidation and weathering minerals in the gouges indicate that the faulting provides favorable conditions for the physical and chemical weathering of rocks. In addition, the crystallinity parameters of dolomite minerals (IC=peak intensity of Al-OH (2 200 nm)/peak intensity of H2O (900 nm)) were calculated based on Near infrared spectrum of altered surrounding rocks in three fault sections. In altered wall rock samples, 637 Platform: IC1=0.078 71/0.037 76≈2.08; 793 Platform: IC2=0.108 8/0.014 8≈7.35; 817Platform: IC3=0.098 6/0.039 1≈2.52. Obviously, the crystallinity of the altered surrounding rock of Platform 793 is significantly higher than the other two platforms. The higher crystallinity means the higher temperature of hydrothermal activity. Therefore, it can be speculated that the sampling location of altered rocks on the Platform 793 may be closer to the hydrothermal activity center. In conclusion, the combination of XRD and NIR spectroscopy analysis methods is helpful for the identification of alteration types and the analysis of mineral crystallinity, which will provide more abundant geological information for the study and the exploration of mineral deposits.

王国强, 曹建劲, 邓永康, 刘翔. 广东大宝山多金属矿床断层剖面矿物X射线衍射和近红外光谱分析及其意义[J]. 光谱学与光谱分析, 2020, 40(2): 610. WANG Guo-qiang, CAO Jian-jin, DENG Yong-kang, LIU Xiang. XRD and NIR Analysis on Minerals of Fault Sections from Dabaoshan Polymetallic Deposit, Guangdong[J]. Spectroscopy and Spectral Analysis, 2020, 40(2): 610.

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