Different Types of Deposits in Porphyry Metallogenic System Identified by 2 200 nm Al—OH Group Vibration
GUO Na1, 2, WANG Xin-chen3*
1. Earth Science College, Chengdu University of Technology，Chengdu 610059, China
2. Geomathematics Key Laboratory of Sichuan Province （Chengdu University of Technology），Chengdu 610059, China
3. College of Information Engineering, Lanzhou University of Finance and Economics, Lanzhou 730020, China
Abstract：2 200 nm Al—OH group vibration is important for the exploration of the deposit in the porphyry metallogenic system. ASD portable spectrometer was used to measure 15 core samples form three different deposit types: Tiegelongnan High- sulfide epithermal deposit, Jiama porphyry deposit and Sinongduo low- sulfide epithermal deposit in Tibet. The results show that: (1) the overall spectral reflectance is 45%~70% in Tiegelongnan, 38%~58% in Jiama and 27%~56% in Sinongduo, the spectral difference is 5~15%; (2) high- sulfide epithermal deposit show a double peak at 2 200 nm, and the other two types show single peak; (3) the spectrum of low- sulfide epithermal deposit enhanced by the second derivative is negative at 2 200 nm, the spectral symmetry and absorption index are also lower than the others; (4) The gaussamp function takes excellent fitting on the single peak spectrum at 2 200 nm (R2=1), which can completely simulate white mica group minerals. The above analysis shows that the 2 200 nm Al—OH group vibration can obviously distinguish different deposits in the porphyry metallogenic system. On the one hand, the presence of illite-smectite in low-sulfide epithermal deposit lead to low reflectance, and the water in minerals result in low values of spectral symmetry and absorption index; On the other hand, the average spectral curve of high-sulfide epithermal deposit takes double peaks because of the kaolinite and dickite minerals, which is the mark for the identification of different epithermal deposits. The study can be applied to aerospace hyperspectral remote sensing exploration by using a 2 200 nm single band.
郭 娜，王馨晨. 2 200 nm的Al—OH基团振动在斑岩成矿系统不同类型矿床中的特征识别[J]. 光谱学与光谱分析, 2023, 43(11): 3492-3496.
GUO Na, WANG Xin-chen. Different Types of Deposits in Porphyry Metallogenic System Identified by 2 200 nm Al—OH Group Vibration. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2023, 43(11): 3492-3496.
