【摘要】 云南会泽铅锌矿床位于扬子板块西缘川-黔-滇铅锌银多金属成矿域的中南部,严格受断裂带的控制.长期以来,对于该矿的成矿流体来源存在着较大的争论.研究表明,矿石中脉石矿物方解石的C、O同位素组成相对均一,其δ13C(PDB)为-2.1×10-3～-3.5×10-3、极差-1.4×10-3、均值-2.8×10-3,δ18O(SMOW)为16.7×10-3～18.6×10-3、极差1.9×10-3、均值17.7×10-3,不同矿体(不同标高)、不同产状以及相同矿体不同产状方解石的C、O同位素组成不具明显差别;除了纯液相包裹体(L)和富液相的气液两相包裹体(L+V)外,还存在含子晶的三相包裹体(S+L+V)和不混溶的CO2三相包裹体(VCO2+LCO2+LH2O),流体包裹体均一温度介于110～400℃之间,具有双峰现象;矿床的(87Sr/86Sr)0(0.713676～0.717012)不仅明显高于地幔(0.704±0.002)和峨嵋山玄武岩(0.703932～0.707818;85件样品)的(87Sr/86Sr)0,也相对高于矿区赋矿地层(C1b)的(87Sr/86Sr)0(0.70868～0.70931;3件样品),但明显低于基底岩石的(87Sr/86Sr)0(0.7243～0.7288;5件样品),且成矿过程中流体基本没有发生Sr同位素分馏现象.因此,成矿流体为均一流体,是不同性质流体的混合产物,具有多源性.而从气液两相包裹体盐度-均一温度图解可以看出,在300～400℃区间,包裹体盐度基本被孤立为两群:一群为5%～6%(w(NaCl)),另一群为12%～16%(w(NaCl)).而在100～300℃特别是150～250℃区间,包裹体盐度则基本均匀分布在7%～23%(w(NaCl))之间.断裂带形成压力为(50～320)×105Pa,矿体上覆岩石压力为(574～640)×105Pa,矿床成矿压力为(145～754)×105Pa.流体在上升到断裂带后压力的剧降,导致了沸腾作用的发生.在混合作用和沸腾作用的双重影响下,受狭窄断裂带控制的成矿流体高度浓缩,金属矿物得以大规模地从流体中沉淀出来,形成品位极高的铅锌矿石.更多还原

【Abstract】 The Huize Pb-Zn ore deposits, Yunnan Province, located in the southern-center of the Sichuan-Yunnan-Guizhou Pb-Zn-Ag multimetal mineralization district, are strictly controlled by faulted zones. There has long been controversy about the sources of ore-forming fluid in these ore deposits. Calcite is one of the gangue minerals in the ores of these ore deposits. Their δ 13C（PDB） values vary from -2.1×10 -3 to -3.5×10 -3, and their δ 18O（SMOW） values are 16.7×10 -3 to 18.6×10 -3. There are no obvious difference in the δ 13C（PDB） values and the δ 18O（SMOW） values of calcites from different orebodies, different occurrences and different elevations. Besides pure liquid inclusions （L） and gas-liquid inclusions with rich liquid （L+V）, three-phase inclusions containing a daughter （S+L+V） and immiscible three-phase CO₂ inclusions （V CO₂+L CO₂+L H₂O） occur in the minerals. The homogenization temperatures of all these inclusions vary from 110℃ to 400℃, and have two peaks. （ 87Sr/ 86Sr）₀ ratios of these ore deposits （0.713676-0.717012） are obviously higher than those of the mantle （0.704±0.002） and Emeishan basalt （0.703932-0.707818; 85 samples）, and slightly higher than those of the Baizuo Formation of Huize lead-zinc ore deposits （0.70868-0.70931; 3 samples）. But all these ratios are lower than the ones of the basement rocks （0.7243-0.7288; 5 samples）. The （ 87Sr/ 86Sr）₀ ratios of these ore deposits also show that the isotopic fractionation of Sr does not occur in the ore-forming fluid during the precipitation of minerals. So, the ore-forming fluid is homogeneous and a product of different fluid mixing.Gas-liquid inclusions can be obviously separated into two groups in the range of 300-400℃ according to their salinities: a group with the salinity of 5%-6% （w（NaCl）） and the other group with the salinity of 12%-16% （w（NaCl））. However, the salinities of inclusions vary from 7% to 23% （w（NaCl）） in the range of 100-300℃, especially the range of 150-250℃. The pressures of faulted zones are 50×105-320×105Pa and the pressures of overlying rocks on the ore bodies are 574×105-640×105Pa, and those of the ore-forming processes vary from 145×105 to 754×105Pa. When the ore-forming fluid flows into the faulted zones, its pressure sharply reduces. Then boiling occurs in the ore-forming processes. As a result of fluids mixing and boiling, the ore-forming fluid is highly concentrated. When the fluid is saturated or oversaturated, metallic minerals begin to precipitate on a great scale. So, the grade of lead-zinc ores is very high.更多还原