Abstract

The Keyue deposit is a medium-sized deposit similar to the Zhaxikang deposit within the North Himalayan Metallogenic Belt (NHMB). The ore formation can be divided into Pb–Zn mineralization (stages 1 and 2), Sb–Ag mineralization (stages 3 and 4), and Sb–Hg mineralization (stages 5 and 6). The fluid inclusion data show that the first two pulses of mineralization have different characteristics, but both belong to the epithermal category (stage 2: 172.9~277.2°C, 7.4~17.0 wt% NaCl eq.; stages 3 and 4: 142.1~321.0°C, 2.7~17.96 wt% NaCl eq.). The H–O isotopic compositions of stages 3 and 4 quartz (δDV-SMOW: –174‰~−120‰, δ18OH2O: 1.59‰~11.34‰) are similar to those of stages 3 and 4 minerals (δDV-SMOW: –165‰~−150‰, δ18OH2O: 6.14‰~13.03‰), whereas they are different from stage 1 and 2 (δDV-SMOW: –108.3‰~−103.6‰, δ18OH2O: 1.92‰~3.82‰) and stage 5 and 6 (δDV-SMOW: –165‰~−138‰, δ18OH2O: −12.91‰~0.82‰) minerals from the Zhaxikang deposit. Additionally, stage 2 sulfides have δ34S values of 5.4‰~11.2‰ that are similar to stage 2 sulfides in the Zhaxikang deposit (7.8‰~12.2‰), and these δ34S values overlap those of many SEDEX-type deposits. The δ34S values also show a decreasing trend from stage 2 through stages 3 and 4 to stage 5 in Keyue and Zhaxikang deposits, which may relate to the overprint by later mineralization events. The Pb isotopic data (206Pb/204Pb: 18.530~19.780, 207Pb/204Pb: 15.674~15.939, and 208Pb/204Pb: 38.618~40.559) show a significant crustal contribution. However, the minerals from different pulses of mineralization also exhibit slightly different Pb isotopic characteristics. These inferences from fluid inclusions and isotope are also demonstrated by geological and mineralogical evidence. Overall, the Keyue deposit is an epithermal deposit and has mainly experienced three pulses of mineralization.

Highlights

  • The North Himalayan Metallogenic Belt (NHMB), located in the most representative orogenic belt worldwide, is an important part of the Tethys-Himalaya metallogenic domain [1]

  • The representative samples are selected for electron probe microanalysis (EPMA), scanning electron microanalysis (SEM), energy-dispersive spectroscopy (EDS), fluid inclusion, and H–O–S–Pb isotopic analyses

  • There are two types of sphalerite in the Keyue deposit: (1) the subhedral– xenomorphic fine-grained sphalerite (0.3~1 mm) coexisting with pyrite, arsenopyrite, and chalcopyrite to form the lamina hosted by Mn–Fe carbonate (Figures 4(a) and 4(b)) and (2) the subhedral-automorphic coarse-grained sphalerite intergrown with pyrite, chalcopyrite, galena, Mn–Fe carbonate, and quartz to form the banded, veined, and massive ores (Figures 4(d)–4(k) and 5(b)–5(d)), with grain size of 3~8 mm

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Summary

Introduction

The North Himalayan Metallogenic Belt (NHMB), located in the most representative orogenic belt worldwide, is an important part of the Tethys-Himalaya metallogenic domain [1]. According to previous research [1,2,3,4], there are mainly three mineralization events within NHMB that generate a series of Sb, Sb–Au, Au, Pb–Zn (Ag), and Sb–Pb–Zn–Ag deposits (Figure 1). The Zhaxikang deposit is the only super-large deposit identified within NHMB, which has the unique metallogenic element association of Sb–Pb–Zn–Ag. The Keyue deposit is a medium-sized deposit near the Zhaxikang deposit; there is only a fault zone separating them. The Keyue deposit is a medium-sized deposit near the Zhaxikang deposit; there is only a fault zone separating them They have similar metallogenic elements and mineral associations, orebody characteristics, ore paragenetic sequence, wall rocks, and so on [1, 10]. Our study has implications for understanding the mineralization and exploration of Sb–Pb–Zn–Ag deposits within NHMB

Geological Setting
44 Zk4405
Materials and Analytical Methods
Mineralogy
Fluid Inclusion
D41-3-1 D39-4-2 D40-2 D39-5-2 D40-1-2 D41-5 ZK003-433-1 D41-8
Discussion
FIs Evidence Implications for the Nature and Origin of Ore-Forming Fluids
Multiple Isotopes Constrain the Ore Genesis
Conclusions
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