Compositions and Pressure-Temperature Conditions of Metamorphic Fluids Overprinting the Talate VMS Pb-Zn Deposit, Southern Altay, China

• Published in: Acta geologica Sinica (Beijing) Vol. 89; no. 3; pp. 794 - 810
• Main Authors: Hui, ZHANG, Jiuhua, XU, Xihui, CHENG, Xuji, GUO, Longhua, LIN, Rui, YANG, Chunjing, BIAN
• Format: Journal Article
• Language: English
• Published: Richmond Blackwell Publishing Ltd 01.06.2015; Wiley Subscription Services, Inc; Resource Engineering Department, University of Science and Technology Beijing, Beijing 100083, China%No.706 Geological Party, Xinjiang Geoexploration Bureau for Nonferrous Metals, Altay 839000,Xinjiang, China
• Edition: English ed.
• Subjects: Altay; Deposits; Fluid dynamics; Fluid flow; Fluid inclusion; Inclusions; Lead (metal); Metamorphic; Metamorphism; Quartz; Talate Pb-Zn deposit; Veins; VMS矿床; 变质流体; 多金属硫化物; 温度条件; 火山喷流沉积; 热液叠加; 绿泥石片岩; 阿尔泰南缘; Talate Pb-Zn deposit; Metamorphism; Fluid inclusion; Altay
• ISSN: 1000-9515; 1755-6724
• DOI: 10.1111/1755-6724.12479

The Talate Pb-Zn deposit,located in the east of the NW-SE extending Devonian Kelan volcanic-sedimentary basin of the southern Altaides,occurs in the metamorphic rock series of the upper second lithological section of the lower Devonian lower Kangbutiebao Formation（D_1k_1~2）.The Pb-Zn orebodies are stratiform and overprinted by late sulfide—quartz veins.Two distinct mineralization periods were identified：a submarine volcanic sedimentary exhalation period and a metamorphic hydrothermal mineralization period.The metamorphic overprinting period can be further divided into two stages：an early stage characterized by bedding-parallel lentoid quartz veins developed in the chlorite schist and leptite of the ore-bearing horizon,and a late stage represented by pyritechalcopyrite-quartz veins crosscutting chlorite schist and leptite or the massive Pb-Zn ores.Fluid inclusions in the early metamorphic quartz veins are mainly CO_2-H_2O-NaCI and carbonic（CO_2±CH_4±N_2） inclusions with minor aqueous inclusions.The CO_2-H_2O-NaCl inclusions have homogenization temperatures of 294-368℃,T_（m,CO2） of-62.6 to-60.5℃,T_（h,CO2） of 7.7 to 29.6℃（homogenized into liquid）,and salinities of 5.5-7.4 wt%NaCl eqv.The carbonic inclusions have T_（m,CO2）of-60.1 to-58.5℃,and T_（h,Co2） of-4.2 to 20.6℃.Fluid inclusions in late sulfide quartz veins are also dominated by CO_2-H_2O-NaCl and CO_2±CH_4 inclusions.The CO_2-H_2O-NaCl inclusions have T_（b,tot） of142 to 360℃,T_（m,CO2）of-66.0 to-56.6℃,T_（h,CO2） of-6.0 to 29.4℃（homogenized into liquid） and salinities of 2.4-16.5 wt%NaCl eqv.The carbonic inclusions have T_（m,Co2）of-61.5 to-57.3℃,and T_（h,CO2） of-27.0to 28.7℃.The aqueous inclusions（L-V） have T_（m,ice） of-9.8 to-1.3℃ and T_（h,tot） of 205 to 412℃.The P-T trapping conditions of CO_2-rich fluid inclusions（100-370 MPa,250-368℃） are comparable with the late- to post-regional metamorphism conditions.The CO_2-rich fluids,possibly derived from regional metamorphism,were involved in the reworking and metal enrichment of the primary ores.Based on these results,the Talate Pb-Zn deposit is classified as a VMS deposit modified by metamorphic fluids.The massive Pb-Zn ores with banded and breccia structures were developed in the early period of submarine volcanic sedimentary exhalation associated with an extensional subduction-related back-arc basin,and the quartz veins bearing polymetallic sulfides were formed in the late period of metamorphic hydrothermal superimposition related to the Permian-Triassic continental collision.