Geochronology and Ore Genesis of the Niujuan-Yingfang Pb-Zn-Ag Deposit in Fengning, Northern North China Craton: Constraints from Fluid Inclusions, H-O-S Isotopes and Fluorite Sr-Nd Isotopes

• Published in: Journal of earth science (Wuhan, China) Vol. 32; no. 1; pp. 81 - 102
• Main Authors: Yan, Xiang, Chen, Bin, Duan, Xiaoxia, Wang, Zhiqiang
• Format: Journal Article
• Language: English
• Published: Wuhan China University of Geosciences 01-02-2021; Springer Nature B.V; Ore Deposit and Exploration Centre(ODEC),Hefei University of Technology,Hefei 230009,China%Department of Earth and Space Sciences,Southern University of Science and Technology,Shenzhen 518055,China; School of Resources and Environmental Engineering,Hefei University of Technology,Hefei 230009,China
• Subjects: Ascent; Base metal; Biogeosciences; Biotite; Carbon dioxide; Chlorite; Cratons; Earth and Environmental Science; Earth Sciences; Fluid inclusions; Fluids; Fluorite; Geochemistry; Geochronology; Geochronometry; Geology; Geotechnical Engineering & Applied Earth Sciences; Gneiss; Heavy metals; Igneous rocks; Isotopes; Lasers; Lead; Low temperature; Metallogenesis; Meteoric water; Mineral deposits; Mineralization; Neodymium; Permian; Pyrite; Quartz; Samarium; Silver; Sodium chloride; Strontium; Sulfur; Sulphur; Zinc; China; fluorite Sr-Nd isotopes; geochronology; H-O-S isotopes; Niujuan-Yingfang Pb-Zn-Ag deposit; fluid inclusion; NCC
• ISSN: 1674-487X; 1867-111X
• DOI: 10.1007/s12583-020-1393-8

The Niujuan-Yingfang Pb-Zn-Ag deposit in northern North China Craton (NCC) is hosted at the contact zone between Permian biotite monzogranite and Hongqiyingzi Group migmatitic gneiss. The orebodies are structurally controlled by NE-trending F
1
fault. Mineralization can be divided into three stages: (1) siliceous-chlorite-pyrite stage, (2) quartz-Ag-base metal stage, and (3) fluoritecalcite stage. Four types of fluid inclusions were identified, including: (1) liquid-rich aqueous inclusions, (2) vapor-rich inclusions, (3) liquid-rich, solid-bearing inclusions, and (4) CO
2
-bearing inclusions. Microthermometric measurements reveal that from stage I to III, the homogenization temperatures range from 317 to 262 °C, from 297 to 192 °C, and from 248 to 151 °C, respectively, and the fluid salinities are in the ranges from 1.1 wt.% to 6.5 wt.%, 1.2 wt.% to 6.0 wt.% and 0.7 wt.% to 4.0 wt.% NaCl equivalents, respectively. Fluid boiling and cooling are the two important mechanisms for ore precipitation according to microthermometric data, and fluid-rock interaction is also indispensable. Laser Raman spectroscopic analyses indicate the fluid system of the deposit is composed of CO
2
-NaCl-H
2
O±N
2
. Metallogenic fluorites yielded a Sm-Nd isochron age of 158±35 Ma. The δ
34
S
V-CDT
values of sulfides range from −1.3‰ to 6.3‰, suggesting that the sulfur may be inherited from the basement metamorphic igneous rocks. Hydrogen and oxygen isotopic compositions of quartz indicate a metamorphic origin for the ore-forming fluid, and the proportion of meteoric water increased during the ore-forming processes. Sr-Nd isotopes of fluorites show a crustal source for the ore-forming fluid, with primary metamorphic fluid mixed with meteoric water during ascent to lower crustal levels. Combined with the geological, metallogenic epoch, fluid inclusions, H-O-S and Sr-Nd isotopes characteristics of the deposit, we suggest that the Niujuan-Yingfang deposit belongs to the medium-low temperature hydrothermal vein-type Pb-Zn-Ag polymetallic deposit, with ore-forming fluids dominantly originated from metamorphic fluids.