In situtrace elements and S isotope systematics for growth zoning in sphalerite from MVT deposits: A case study of Nayongzhi, South China

Abstract

Zoning texture in sphalerite has been described in many studies, although its genesis and ore formation process are poorly constrained. In this investigation, we compare the in situ trace element and isotopic composition of colour-zoned sphalerites from Nayongzhi, South China, to explain the zoning growth process. Petrographic observations identified two broad types of zoned sphalerite, core–rim (CR) and core–mantle–rim (CMR) textures. Each zoned sphalerite displays two or three colour zones, including brown core, light colour bands and/or pale-yellow zones. In situ laser ablation inductively coupled plasma mass spectrometry trace-element analyses show that the three colour zones display variable trace-element compositions. Brown cores exhibit distinctly high Mn, Fe, Co, Ge, Tl and Pb concentrations, whereas pale-yellow and light colour zones have elevated Ga, Cd, Sn, In and Sb concentrations. Copper, Sb, In and Sn show slight variations between pale-yellow and light zones, the latter having higher In and Sn, but lower Cu and Sb abundances. Given the low concentration range of Pb, Ge, Tl, Mn Sb, Cd, etc., the colour of sphalerite is attributed mainly to Fe compositional variation. The δ34S values of sphalerite from Nayongzhi range from +22.3 to +27.9‰, suggesting reduced sulfur was generated by thermochemical sulfate reduction of marine sulfate in ore-hosted strata. Single-crystal colour-zoned sphalerite exhibits intracrystalline δ34S variation (up to 4.3‰), which is attributed to the δ34S composition of H2S in the original fluid. The lack of correlation between trace elements and δ34S values indicates episodic ore solution influxes and mixes with the reduced sulfur-rich fluid derived from the aquifers of the ore-hosted strata, which play a key role in the formation of the zoned Nayongzhi sphalerite. In conclusion, in situ trace element and S isotope studies of zoned sphalerite crystals might provide insight into the ore-forming process of MVT deposits.

Optimization of Plane Image Color Enhancement Based on Computer Vision

“…Up to now, the technology is still in the stage of popularization. As China's development ability in machine vision hardware and software is not very strong, there is a certain gap between domestic MVT and foreign MVT, resulting in high development cost and low efficiency of related products [12]. In recent years, domestic research institutes, universities, and related enterprises have increased their research on MVT and applied the technology to industrial sites, such as electronic manufacturing, semiconductor industry, and pharmaceutical industry.…”

Sphalerite Records Cd Isotopic Signatures of the Parent Rocks in Hydrothermal Systems: A Case Study From the Nayongzhi Zn–Pb Deposit, Southwest China

“…Previous studies have reported bulk S isotopic compositions of sphalerite from the Nayongzhi deposit, which have δ 34 S = 17.2–25.5‰ (Jin et al., 2016; Zhou et al., 2018), whereas the in situ S isotopic compositions of different colored sphalerite zones vary from 22.3 to 27.9‰ (Wei et al., 2021). In contrast, Zhou et al.…”

“…(c) Geological map of the Wuzhishan anticline showing the location of Zn-Pb ore deposits. The figure was taken and modified fromWei et al (2018Wei et al ( , 2021.…”

LA-ICP-MS Trace Element Geochemistry of Sphalerite and Metallogenic Constraints: A Case Study from Nanmushu Zn–Pb Deposit in the Mayuan District, Shaanxi Province, China

“…Blocks of two standards (one NIST 610 and one GSE-2G) and one MASS-1 sulfide standard analyses were followed by five to eight unknown samples. For sphalerite, the following 18 isotopes were measured (with their respective dwell times in milliseconds listed in parentheses): 34 S, 55 Mn, 57 Fe, 59 Co, 60 Ni, 65 Cu, 66 Zn, 71 Ga, 74 Ge, 75 As, 77 Se, 107 Ag, 111 Cd, 118 Sn, 121 Sb, 126 Hg, 205 Tl, and 208 Pb, corresponding to a total dwell time of 180 ms. The MASS-1 sulfide standard [37] was used as the primary standard for calibrating 34 S, 55 Mn, 57 Fe, 59 Co, 60 Ni, 65 Cu, 66 Zn, 71 Ga, 74 Ge, 75 As, 77 Se, 107 Ag, 111 Cd, 118 Sn, 121 Sb, 126 Hg, 205 Tl, and 208 Pb.…”

“…In these ternary plots, the Nanmushu sphalerite also falls into the MVT field, which is clearly different from the SEDEX, VMS, and Skarn deposits. [5,13,14,[65][66][67][68][69][70][71]; MVT data are collected from references [3,5,18,30,[41][42][43]50,66,[72][73][74]; SEDEX data are collected from references [75][76][77][78][79]; Skarn data are collected from references [3,5,13,14,67,[80][81][82]; and VMS data are collected from references [3,5,66,83,84].…”