Magmatic-hydrothermal fluid evolution of the tin-polymetallic metallogenic systems from the Weilasituo ore district

Northeast China

authored by: Xu Gao, Zhenhua Zhou, Karel Breiter, Jingwen Mao, Rolf L. Romer, Nigel J. Cook, François Holtz
Abstract: The large Weilasituo Sn-polymetallic deposit is a recent exploration discovery in the southern Great Xing’an Range, northeast China. The ore cluster area shows horizontal mineralization zoning, from the inner granite body outward, consisting of high-T Sn–W–Li mineralization, middle-T Cu–Zn mineralization and peripheral low-T Pb–Zn–Ag mineralization. However, the intrinsic genetic relationship between Sn-W-Li mineralization and peripheral vein-type Pb–Zn–Ag–Cu mineralization, the formation mechanism and the deep geological background are still insufficiently understood. Here, we use fluid inclusions, trace elements concentrations in quartz and sphalerite, and H–O isotope studies to determine the genetic mechanism and establish a metallogenic model. Fluid inclusion microthermometry and Laser Raman spectroscopic analysis results demonstrates that the aqueous ore-forming fluids evolved from low-medium salinity, medium–high temperature to low salinity, low-medium temperature fluids. Laser Raman spectroscopic analysis shows that CH₄ is ubiquitous in fluid inclusions of all ore stages. Early ore fluids have δ¹⁸O_{H2O (v–SMOW)} values from + 5.5 to + 6.2‰ and δD values of approximately − 67‰, concordant with a magmatic origin. However, the late ore fluids shifted toward lower δ¹⁸O_{H2O (v–SMOW)} (as low as 0.3‰) and δD values (~ − 136‰), suggesting mixing between external fluids derived from the wall rocks and a contribution from meteoric water. Ti-in-quartz thermometry indicates a magmatic crystallization temperature of around 700 °C at a pressure of 1.5 kbar for the magmatic ore stage. Cathodoluminescence (CL) imaging and trace element analysis of quartz from a hydrothermal vug highlight at least three growth episodes that relate to different fluid pulses; each episode begins with CL-bright, Al-Li-rich quartz, and ends with CL-dark quartz with low Al and Li contents. Quartz from Episode 1 formed from early Sn-(Zn)-rich fluids which were likely derived from the quartz porphyry. Quartz from episodes 2 and 3 formed from Zn-(Sn)-Cu-rich fluid. The early magmatic fluid is characterized by low fS₂. The SO₂ produced by magma degassing reacted with heated water to form SO₄²⁻, causing the shift from low fS₂ to high fS₂. The SO₄²⁻ generated was converted to S^2– by mixing with CH₄-rich, Fe and Zn-bearing external fluid which led to late-stage alteration and dissolution of micas in vein walls, thus promoting crystallization of pyrrhotite, Fe-rich sphalerite and chalcopyrite and inhibiting the precipitation of anhydrite. This study shows that ore formation encompassed multiple episodes involving steadily evolved fluids, and that the addition of external fluids plays an important role in the formation of the later Cu–Zn and Ag–Pb–Zn mineralization in the Weilasituo ore district.
Organisation(s): Institute of Mineralogy
External Organisation(s): Chinese Academy of Geological Sciences (CAGS)
Australian National University
Czech Academy of Sciences (CAS)
Helmholtz Centre Potsdam - German Research Centre for Geosciences (GFZ)
University of Adelaide
Type: Article
Journal: Scientific reports
Volume: 14
No. of pages: 22
ISSN: 2045-2322
Publication date: 06.02.2024
Publication status: Published
Peer reviewed: Yes
ASJC Scopus subject areas: General
Electronic version(s): https://doi.org/10.1038/s41598-024-53579-y (Access: Open)

BibTeX

@article{2c3b01bacbc54b759a9a10541477781f,
title = "Magmatic-hydrothermal fluid evolution of the tin-polymetallic metallogenic systems from the Weilasituo ore district: Northeast China",
abstract = "The large Weilasituo Sn-polymetallic deposit is a recent exploration discovery in the southern Great Xing{\textquoteright}an Range, northeast China. The ore cluster area shows horizontal mineralization zoning, from the inner granite body outward, consisting of high-T Sn–W–Li mineralization, middle-T Cu–Zn mineralization and peripheral low-T Pb–Zn–Ag mineralization. However, the intrinsic genetic relationship between Sn-W-Li mineralization and peripheral vein-type Pb–Zn–Ag–Cu mineralization, the formation mechanism and the deep geological background are still insufficiently understood. Here, we use fluid inclusions, trace elements concentrations in quartz and sphalerite, and H–O isotope studies to determine the genetic mechanism and establish a metallogenic model. Fluid inclusion microthermometry and Laser Raman spectroscopic analysis results demonstrates that the aqueous ore-forming fluids evolved from low-medium salinity, medium–high temperature to low salinity, low-medium temperature fluids. Laser Raman spectroscopic analysis shows that CH4 is ubiquitous in fluid inclusions of all ore stages. Early ore fluids have δ18OH2O (v–SMOW) values from + 5.5 to + 6.2‰ and δD values of approximately − 67‰, concordant with a magmatic origin. However, the late ore fluids shifted toward lower δ18OH2O (v–SMOW) (as low as 0.3‰) and δD values (~ − 136‰), suggesting mixing between external fluids derived from the wall rocks and a contribution from meteoric water. Ti-in-quartz thermometry indicates a magmatic crystallization temperature of around 700 °C at a pressure of 1.5 kbar for the magmatic ore stage. Cathodoluminescence (CL) imaging and trace element analysis of quartz from a hydrothermal vug highlight at least three growth episodes that relate to different fluid pulses; each episode begins with CL-bright, Al-Li-rich quartz, and ends with CL-dark quartz with low Al and Li contents. Quartz from Episode 1 formed from early Sn-(Zn)-rich fluids which were likely derived from the quartz porphyry. Quartz from episodes 2 and 3 formed from Zn-(Sn)-Cu-rich fluid. The early magmatic fluid is characterized by low fS2. The SO2 produced by magma degassing reacted with heated water to form SO42−, causing the shift from low fS2 to high fS2. The SO42− generated was converted to S2– by mixing with CH4-rich, Fe and Zn-bearing external fluid which led to late-stage alteration and dissolution of micas in vein walls, thus promoting crystallization of pyrrhotite, Fe-rich sphalerite and chalcopyrite and inhibiting the precipitation of anhydrite. This study shows that ore formation encompassed multiple episodes involving steadily evolved fluids, and that the addition of external fluids plays an important role in the formation of the later Cu–Zn and Ag–Pb–Zn mineralization in the Weilasituo ore district.",
keywords = "Fluid mixing, H-O isotopes, In situ LA-ICP-MS trace element analysis, Physico-chemical conditions, Sn-polymetallic ore systems",
author = "Xu Gao and Zhenhua Zhou and Karel Breiter and Jingwen Mao and Romer, {Rolf L.} and Cook, {Nigel J.} and Fran{\c c}ois Holtz",
note = "Funding Information: This work was financially supported by the National Natural Science Foundation of China (Grant No. 41772084), the Science & Technology Fundamental Resources Investigation Program (Grant Nos. 2022YF101900 and 2022YF101901), and a grant from the China Scholarship Council (Grant No. 201908110162). Boyang Li, Xu Fu, Kexiang Wang, Peng Sheng, Dawei Jiang and Hucan Jiang are thanked for their field support. Cooperation of KB was supported by the Czech Science Foundation, project No. P210/19/05198S, and by RVO 67985831 of the Institute of Geology of the Czech Academy of Sciences. ",
year = "2024",
month = feb,
day = "6",
doi = "10.1038/s41598-024-53579-y",
language = "English",
volume = "14",
journal = "Scientific reports",
issn = "2045-2322",
publisher = "Nature Publishing Group",
}