Mineralium Deposita

, Volume 47, Issue 5, pp 467–482

Fluid inclusion study of the Wunugetu Cu–Mo deposit, Inner Mongolia, China

Article

DOI: 10.1007/s00126-011-0384-1

Cite this article as:
Li, N., Chen, Y., Ulrich, T. et al. Miner Deposita (2012) 47: 467. doi:10.1007/s00126-011-0384-1

Abstract

Hydrothermal alteration and mineralization at the Wunugetu porphyry Cu–Mo deposit, China, include four stages, i.e., the early stage characterized by quartz, K-feldspar and minor mineralization, followed by a molybdenum mineralization stage associated with potassic alteration, copper mineralization associated with sericitization, and the last Pb–Zn mineralization stage associated with carbonation. Hydrothermal quartz contains three types of fluid inclusions, namely aqueous (W-type), daughter mineral-bearing (S-type) and CO2-rich (C-type) inclusion, with the latter two types absent in the late stage. Fluid inclusions in the early stage display homogenization temperatures above 510°C, with salinities up to 75.8 wt.% NaCl equivalent. The presence of S-type inclusions containing anhydrite and hematite daughter minerals and C-type inclusions indicates an oxidizing, CO2-bearing environment. Fluid inclusions in the Mo- and Cu-mineralization stages yield homogenization temperatures of 342–508°C and 241–336°C, and salinities of 8.6–49.4 and 6.3–35.7 wt.% NaCl equivalent, respectively. The presence of chalcopyrite instead of hematite and anhydrite daughter minerals in S-type inclusions indicates a decreasing of oxygen fugacity. In the late stage, fluid inclusions yield homogenization temperatures of 115–234°C and salinities lower than 12.4 wt.% NaCl equivalent. It is concluded that the early stage fluids were CO2 bearing, magmatic in origin, and characterized by high temperature, high salinity, and high oxygen fugacity. Phase separation occurred during the Mo- and Cu-mineralization stages, resulting in CO2 release, oxygen fugacity decrease and rapid precipitation of sulfides. The late-stage fluids were meteoric in origin and characterized by low temperature, low salinity, and CO2 poor.

Keywords

Fluid inclusionWunugetu porphyry Cu–Mo depositGreat Hinggan RangeChina

Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  • Nuo Li
    • 1
  • Yan-Jing Chen
    • 1
  • Thomas Ulrich
    • 2
  • Yong Lai
    • 1
  1. 1.Key Laboratory of Orogen and Crust EvolutionPeking UniversityBeijingChina
  2. 2.Department of Earth SciencesAarhus UniversityAarhusDenmark