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Geoscience ›› 2018, Vol. 32 ›› Issue (03): 415-428.DOI: 10.19657/j.geoscience.1000-8527.2018.03.01

• Mineral Deposits and Petrology • Previous Articles     Next Articles

Study on Evolution of Ore-forming Fluid in the Sadaigoumen Molybdenum Deposit, Hebei Province

WU Di1,2,3(), JIANG Sihong1(), LIU Yuan4, ZHANG Lili1, KANG Huan1, LIU Jiajun2,5   

  1. 1. MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037,China
    2. School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083,China
    3. No.1 Gold Geological Party of Armed Police Force, Mudanjiang,Heilongjiang 157000,China
    4. School of Geosciences, China University of Petroleum, Beijing 102249,China
    5. State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, China
  • Received:2017-12-25 Revised:2018-02-22 Online:2018-06-10 Published:2018-06-28
  • Contact: JIANG Sihong

Abstract:

The Sadaigoumen Mo deposit is a typical porphyry Mo deposit in the Yan-Liao Mo(Cu) metallogenic belt on the northern margin of North China Block. Located in Fengning County, Hebei Province, the Sadaigoumen Mo deposit is the largest molybdenum deposit in this region so far. The Mo mineralization can be divided into three periods, which are pre-ore period (quartz vein stage without mineralization), the syn-ore period (including ①quartz+magnetite+molybdenite+pyrite+K-feldspar stage, ②quartz+molybdenite stage, ③quartz+mica+molybdenite+pyrite stage, and ④quartz+molybdenite+pyrite stage), and the post-ore period (late hydrothermal stage without mineralization). In order to explore the ore-forming mechanism of this Mo deposit, the study on ore fluid was carried out in this paper. There are two types of fluid inclusions in this deposit, which consist of two-phase vapor-liquid inclusions and CO2-bearing three-phase inclusions. The quartz from the pre-ore and post-ore periods are predominantly characterized by the two-phase vapor-liquid inclusions, which have the homogenization temperatures ranging from 248 to 296 ℃, 130 to 197 ℃, and the salinities varying from 6.0% to 10.2% NaCleqv, and 0.2% to 5.9% NaCleqv for the pre-ore and post-ore periods, respectively. During the syn-ore period, the two types of fluid inclusions are both developed in quartz, with the homogenization temperatures and salinities ranging from 200 to 260 ℃, and from 7.0% to 17.5% NaCleqv. Raman spectrum and inclusion groups components studies indicate that ore fluids are mainly composed of CO2, H2O,N2, Na+,Ca2+,NO3- and Cl-. The δD and δ18$O_{H_{2}O}$ values for quartz from ores vary from -88‰ to -102‰, and -1.90‰ to 3.12‰, respectively. Therefore, the ore fluid in the Sadaigoumen Mo deposit is a CO2-H2O-NaCl system dominated by the magmatic water in a medium-low temperature and medium-low salinity.

 

Key words: molybdenum deposit, fluid inclusion, microthermometry, Raman spectrum, Sadaigoumen, Hebei

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