Abstract:

Zhifang molybdenum deposit in Songxian County of Henan Province is a K-feldspar quartz-vein-typed deposit occurring along the strata of Middle Proterozoic volcanic rock. The stratiformlike and lenticular mineralized quartz veins, with a thickness ranging from 0.35 to 5.0 m, appear parallel and dense and have a conformable contact with enclosing rocks. The mineralized quartz veins can be classified into three stages. The early stage quartz veins without ore is compact and massive. The quartz veins of middle stage are molybdenum mineralized while the quartz veins of late stage are small veins containing quartz and carbonate but no ore. Geochemical study shows that the oreforming material comes mainly from volcanic hydrothermal fluid and ore-forming time is consistent with that of late Xiong'er volcanic eruption stage. Ore-forming fluid compositions, eigenvalue of liquid facies components, and H and O isotopes show that the mixed fluid of medium and high temperature results from high temperatured geological action. Fluid inclusions show that ore-formation results from the interaction of immiscible fluid and ebullition of hydrothermal fluid. The metallogenic pressure is 28×10⁵ to 68×10⁵ Pa, suggesting that ore-formation results from the packing of hydrothermal fluid into volcanic edifice under low pressure and epithermal condition.

Key words: font-family: "Times New Roman", mso-bidi-font-size: 12.0pt, mso-font-kerning: 1.0pt, mso-ansi-language: EN-US, mso-fareast-language: ZH-CN, mso-bidi-language: AR-SA, mso-fareast-font-family: 宋体">Songxian County, Xiong‘font-family: "Times New Roman", mso-bidi-font-size: 12.0pt, mso-font-kerning: 1.0pt, mso-ansi-language: EN-US, mso-fareast-language: ZH-CN, mso-bidi-language: AR-SA, mso-fareast-font-family: 宋体">er Group, K-font-family: "Times New Roman", mso-bidi-font-size: 12.0pt, mso-font-kerning: 1.0pt, mso-ansi-language: EN-US, mso-fareast-language: ZH-CN, mso-bidi-language: AR-SA, mso-fareast-font-family: 宋体">feldspar quartz-vein, fluid inclusion