Raman Spectral Characteristics of Pyrite in Luyuangou Gold Deposit, Western Henan Province and Its Indicative Significance for Multiphase Metallogenesis
ZHANG Jian1, LIU Ya-jian2, CAO Ji-hu3
1. School of Earth Sciences, East China University of Technology, Nanchang 330013, China
2. Henan University of Economics and Law, Zhengzhou 450016, China
3. Henan Bureau of Nonferrous Metals Geology and Mineral Resources, Zhengzhou 450016, China
Abstract：Luyuangou gold deposit is an important fractured altered gold deposit in Xiong’er Mountain, and pyrite is its main gold-bearing mineral. Testing the major elements, trace elements and isotope of pyrite can analyze the mineralization process of gold deposits. The conventional testing methods mainly include electron microprobe and laser-ablation inductively coupled plasma mass spectrometry, but these methods have the disadvantages of long test times and high costs. Because of forming under different temperature and pressure conditions, the spectral characteristics of pyrite are different. Conducting laser Raman test to analyze the displacement of Raman characteristic peaks and the change of full width at half maximum (FWHM), we can judge the temperature and pressure of pyrite formation and further infer the mineralization process of gold deposit, which has economic and efficient advantages compared with traditional analysis and test methods. Analyzing Raman spectroscopic of pyrite samples at a different elevation from 430 to 670 m, it found that the characteristic Raman displacement Ag near 379 cm-1 showed an increasing trend from elevation 430 to 500 m, the decreasing trend from elevation 500 to 580 m and a increasing trend from elevation 580 to 670 m. The Ag generally increases with mineralization pressure, and it is inferred that there are two phases of tectonic activity in the ore-controlling structure. The fragmentation zone of the first phase of tectonic activity reaches about elevation of 500 m, and the second phase of structural activity continues to develop upward based on the first phase, reaching an elevation of about 670 m. The FWHM of the characteristic peak at 379 cm-1 can indicate the crystallization and order of pyrite crystals. Generally, the wider FWHM of the characteristic peak, the worse crystallinity and order, and the higher the crystallization and precipitation temperature. The FWHM of gold-bearing pyrite near the peak of 379 cm-1 from elevation 430 to 500 m, increased gradually from 7.94 to 12.81, and from elevation 500 to 670 m, it gradually decreased from 12.81 to 8.81. It is speculated that corresponding to the two-phase structure-activity. There are two-phase hydrothermal activities. Electron microprobe sweeps analysis of pyrite at elevation 430 m revealed -two-phase hydrothermal activity indeed, with low As content in the first phase and higher As content in the second phase. Raman spectroscopy of pyrite formed from the second hydrothermal phase at elevation 430 m with Ag of 381.86 indicating the lower crystallization and precipitation pressure and FWHM of 12.80 indicating the higher crystallization and precipitation temperature, which testify the inferred geology process.
张 健，刘亚剑，曹纪虎. 豫西陆院沟金矿黄铁矿拉曼光谱特征及其对多期成矿的指示意义[J]. 光谱学与光谱分析, 2022, 42(12): 3770-3774.
ZHANG Jian, LIU Ya-jian, CAO Ji-hu. Raman Spectral Characteristics of Pyrite in Luyuangou Gold Deposit, Western Henan Province and Its Indicative Significance for Multiphase Metallogenesis. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2022, 42(12): 3770-3774.
