(1. 昆明理工大學(xué) 國土資源工程學(xué)院，昆明 650093；
2. 有色金屬礦產(chǎn)地質(zhì)調(diào)查中心西南地質(zhì)調(diào)查所，昆明 650093；
3. 昆明理工大學(xué) 城市學(xué)院，昆明 650093)
摘 要: 金牛廠鉛鋅礦床是川滇黔鉛鋅多金屬成礦區(qū)滇東北礦集區(qū)內(nèi)產(chǎn)于下寒武統(tǒng)筇竹寺組泥質(zhì)、鈣質(zhì)粉砂巖中的鉛鋅礦床，屬于非碳酸鹽巖容礦的后生熱液礦床。區(qū)內(nèi)賦礦地層筇竹寺組Pb、Zn含量異常高，而礦石Pb同位素組成與基底巖石(昆陽群)基本一致，礦源層是基底還是筇竹寺組、該礦床與區(qū)內(nèi)其他賦存于碳酸鹽巖中的鉛鋅礦床成礦機(jī)理是否具有一致性，直接關(guān)系到鉛鋅成礦系統(tǒng)研究與礦床深部找礦預(yù)測。基于流體包裹體測溫及硫化物H-O-S-Pb同位素組成分析，結(jié)果表明：1) 流體包裹體均一溫度為165~274 ℃，平均216 ℃；鹽度為6.5%~14.0%NaCleqv，平均值為7.8%NaCleqv，指示成礦流體屬于中低溫-中低鹽度的富氣相流體；顯微激光拉曼光譜分析顯示流體包裹體的液相成分主要為H2O，氣相成分主要為CH4；2) 脈石礦物石英的H、O同位素特征表明，成礦流體主要來源于流經(jīng)深部褶皺基底(昆陽群)的深部流體和含有機(jī)質(zhì)的盆地鹵水的混合；3) 硫化物δ34 S值與川滇黔成礦區(qū)內(nèi)主要鉛鋅礦床具有相似性，其還原S主要來源于下伏地層震旦系燈影組和下寒武統(tǒng)漁戶村組白云巖中硫酸鹽的熱化學(xué)還原硫作用(TSR)過程；4) 硫化物的Pb同位素組成不僅與基底巖石的鉛同位素比值一致，且沿上地殼Pb平均演化線呈直線分布，表明殼源Pb源主要來自基底巖石(昆陽群)，賦礦圍巖下寒武統(tǒng)筇竹寺組碎屑巖也貢獻(xiàn)了部分Pb。結(jié)合礦床對比研究，認(rèn)為該礦床和川滇黔成礦區(qū)內(nèi)主要鉛鋅礦床是在同一成礦地質(zhì)背景下形成，具有相似的成礦模式，但在賦礦圍巖、賦礦斷裂性質(zhì)、礦質(zhì)來源等方面存在自身的特點(diǎn)。該研究可為川滇黔成礦區(qū)內(nèi)鉛鋅成礦系統(tǒng)研究提供依據(jù)，也為該區(qū)礦床深部及外圍找礦提供新思路。
關(guān)鍵字: 流體包裹體測溫；H-O-S-Pb同位素；成礦物質(zhì)來源；成礦模式；金牛廠鉛鋅礦床
（1. Kunming University of Science and Technology, Faculty of Land Resources Engineering, Kunming 650093, China;
2. SouthwestInstitute of Geological Survey, Geological Survey Center for Non-ferrous Metals Resources, Kunming 650093, China;
3. City College, Kunming University of Science and Technology, Kunming 650093, China）
Abstract:The Jinniuchang Pb-Zn deposit hosted in the argillaceous and calcareous siltstone of the Lower Cambrian Qiongzhusi Formation is a non-carbonate-hosted epigenetic hydrothermal deposit in the deposit-concentrated district in northeastern Yunnan of the Sichuan–Yunnan–Guizhou Pb-Zn polymetallic metallogenic triangle area(SYGT). The content of Pb and Zn in the ore-bearing strata of the mining area is abnormally high, and the Pb isotopic composition of the ore is basically consistent with that of the basement rocks (Kunyang group). Whether the ore source layer is the basement or the Qiongzhusi Formation, and whether the Jinniuchang deposit has the same metallogenic mechanism as other carbonate-hosted Pb-Zn deposits in the district, which are related to the Pb-Zn metallogenic system and the prospecting potential of deep deposits. Based on the microthermometry of fluid inclusions and the sulfide H-O-S-Pb isotopic composition analysis, the following results are achieved: 1) The homogenisation temperatures of fluid inclusions in quartz range from 165 ℃ to 274 ℃, with an average value of 216 ℃; the salinity range from 6.5% to 14.0% NaCleqv, with an average value of 7.8% NaCleqv, indicating the ore-forming fluid belongs to the gas-rich fluid with medium-low temperature and medium-low salinity. Microscopic laser Raman spectroscopy analysis shows that the liquid phase composition of fluid inclusions is mainly H2O, and the gas phase composition is mainly CH4. 2) The H and O isotopic composition characteristics of the gangue mineral quartz indicate that the ore-forming fluid is mainly derived from the mixing of deep source metamorphic water flowing through deep fold basement (Kunyang group) and organic-containing basin brine. 3) The sulfides'''' δ34S values are similar to the main Pb-Zn deposits in the SYGT, which is interpreted as that the reduced S is mainly derived from sulfates in marine sedimentary rocks in dolomites of the Sinian Dengying Formation and the Lower Cambrian Yuhucun Formation through thermochemical reduction of sulfur (TSR). 4) Sulfides have Pb isotopic compositions that form a linear trend on the average crustal Pb growth curve in 207Pb/204Pb vs. 206Pb/204Pb plot. Moreover, Pb isotopic ratios are consistent with the basement rocks, consequently suggesting crustal Pb sources with the majority of Pb are derived from the basement rocks (Kunyang group). The clastic rocks of the Lower Cambrian Qiongzhusi Formation also provide part of the Pb sources. Combined with the comparative study of the deposit, we conclude that the Jinniuchang deposit and major Pb-Zn deposits in the SYGT formed under the same metallogenic geological background and had a similar metallogenic model, but the Jinniuchang deposit has its own characteristics in terms of ore-bearing wall rock, ore-bearing fracture properties, and mineral sources. This achievement provides a basis for the study of the Pb-Zn metallogenic system and a new idea for the deep and peripheral prospecting of the Pb-Zn deposits in the SYGT.
Key words: microthermometry of fluid inclusions; H-O-S-Pb isotopes; source of ore-forming materials; metallogenic model; Jinniuchang Pb-Zn deposit
