XRD and NIR Analysis on Minerals of Fault Sections from Dabaoshan Polymetallic Deposit, Guangdong
WANG Guo-qiang1, 2, 3, 4, CAO Jian-jin1, 2, 3, 4*, DENG Yong-kang1, 2, 3, 4, LIU Xiang1, 2, 3, 4
1. School of Earth Sciences and Engineering, Sun Yat-sen University, Guangzhou 510275, China
2. Guangdong Provincial Key Laboratory of Mineral Resources & Geological Processes, Guangzhou 510275, China
3. Guangdong Provincial Key Lab of Geodynamics and Geohazards, Guangzhou 510275, China
4. Southern Laboratory of Ocean Science and Engineering, Zhuhai 519082, China
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.
Key words：Polymetallic deposit; Near infrared spectroscopy; X-ray diffraction; Fault sections
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(02): 610-615.
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. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2020, 40(02): 610-615.
