Re-Os Isotope Characteristics of the Huize Ultra-large Lead-Zinc Deposit, Northeastern Yunnan Province: Constraints on the Himalayan Metallogenic Dynamic Background

Abstract

BACKGROUND The Huize ultra-large lead-zinc deposit is a typical MVT or HZT type deposit in the lead-zinc polymetallic belt. This deposit is known as a unique metallogenic system and germanium enrichment. Due to the low mineralization temperature and lack of suitable dating minerals, the age of the ore deposits has been controversial. OBJECTIVES To precisely date the mineralization age by Negative Thermal Ionization Mass Spectrometry (NTIMS) Re-Os isotope analyses and discuss the Himalayan metallogenic dynamic process in the Huize ultra-large lead-zinc deposit. METHODS NTIMS Re-Os isotope analyses were carried out on pyrite, galena, and sphalerite samples collected from the Huize ultra-large lead-zinc deposit. The Re-Os isochron age from the pyrite, galena, and sphalerite samples was used to constrain mineralization age. The initial 187Os/188Os values were used to trace the material sources. RESULTS The Re-Os isochron age of the pyrite samples is 40.7±2.6 Ma (2σ, n=9) with a model weighted average age of 40.0±2.6 Ma (2σ, n=8). The sphalerite and galena samples have model ages of 38.24±0.41 Ma and 36.57±0.40 Ma, respectively. Furthermore, the initial 187Os/188Os values of the pyrite samples vary from 0 to 0.26, whereas those of the sphalerite and galena samples are 0.46 and 0.41, respectively. CONCLUSIONS The Re-Os isochron ages indicate that the mineralization for the Huize ultra-large lead-zinc deposit occurred during the Eocene period. Based on regional ore controlling structure, tectono-lithofacies alteration characteristics in Northeastern Yunnan and the isochron ages results, a two-stage (Yanshanian and Himalayan) tectonic-fluid metallogenic model for the Huize Ultra-large lead-zinc deposit is inferred.

Keywords

• northeastern yunnan province
• huize lead-zinc deposit
• regional structural analysis
• re-os isotope chronlogy