热液矿床中Pb的迁移和沉淀机制研究综述  

Mechanisms of Lead Transportation and Deposition in Hydrothermal Deposits

作　　者：陈贤[1,2] 刘家军[1,2] 李彦春[3] 王艳龙[4] 张德会[1,2] 陶银龙[1,2] 曹强[1,2] 

机构地区：[1]中国地质大学地质过程与矿产资源国家重点实验室,北京100083 [2]中国地质大学地球科学与资源学院,北京100083 [3]中国冶金地质总局昆明地质勘查院,昆明650201 [4]河北省区域地质矿产调查研究所,河北廊坊065000

出　　处：《地质科技情报》2015年第3期45-57,共13页Geological Science and Technology Information

基　　金：国家自然科学基金项目(41030423);中国地质调查地质矿产调查评价专项(1212011220924)

摘　　要：岩浆结晶过程中,矿物-熔体相分离时,Pb优先进入熔体相,表现出不相容性;流体-熔体相分离时,Pb优先进入流体相;卤水-气相分离时,Pb优先进入卤水相;Pb在成矿过程中主要进入液相中进行迁移。氧化、偏酸性、富氯热液体系中,Pb主要以PbCl2-nn(0≤n≤4)形式迁移,尤其在高于350℃的高温环境下,Pb的氯络合物起支配作用;中低温、贫氯、高还原硫的碱性热液中,Pb主要以硫氢络合物形式迁移;氧化、贫氯的强碱性(pH>7.5)热液中,Pb主要以羟基络合物形式迁移;贫Cl-且富CO32-和HCO-3配体的中、低温弱碱性热液体系中,PbCO03、Pb(CO3)2-2络合物也很重要。NH3、F-、Br-、S2-x、NaPbCl03、NaPbCl4-以及S2O2-3等潜在无机配体对Pb迁移成矿意义不大。某些有机配体,如羧酸、氨基酸、腐殖酸,在低温(<200℃)条件下对Pb的运移成矿有重要作用,尤其羧酸比较重要。在成矿过程中,岩浆-热液成因的Pb-Zn矿床通常经历了早期岩浆房去气、期后热液和晚期热液3个阶段。非岩浆热液成因的层控Pb-Zn矿床流体主要为盆地卤水,矿化机制主要为构造挤压与重力的联合驱动,或者伸展背景下的海底热液对流。影响Pb沉淀富集的微观因素主要包括热液组成、温度、压力、pH值以及Eh值等。热液演化过程中,沸腾减压、围岩蚀变以及流体混合等地质作用促使上述微观物理化学因素发生显著变化,形成地球化学障,从而使得矿石矿物大量沉淀。In the process of magmatic crystallization, we insist that： when mineral and melt phase is separa- ted, lead is into the melt phase more preferentially, and lead is not compatible; when fluid and melt phase is in separation, lead is more likely to enter the fluid phase; when brine and vapor is in separation, lead preferentially enters into the brine phase l during the process of ore-forming, lead mainly enters into the liquid phase and is transported. In the magmatic hydrothermal solutions, oxidation, partial acid, chlorine- rich and sulfide-poor, PbCI^-n （0~n^4） complex is the most important form of transporting lead, but the factors, such as temperature and chloride concentration, determine the specific speciation. More than 350 ℃, PbCI2n-n- （0≤n≤4） plays a dominant role （especially PbC1＋ , PbCI0 0）, and other types of complexes are not stable at high temperature; under the conditions,200--350℃, poor CI- , rich sulfide and alkaline, lead may be more conducive to form sulfur hydrogen complex and transport lead more than 10 ppm, and below 200℃, in chloride-poor hydrothermal solution, sulfur hydrogen complex of lead is insignificant to form e- conomic deposits, however, organic complex of lead is important. For oxidized conditions, hydrothermal being of poor C1 and rich C1- but alkaline （pH〉7.5）, hydroxide complexes of Pb is dominant. Under low temperature, poor CI- and mildly alkaline conditions, with sufficient concentration of CO2-3- and HCO3- ligands, carbonate complexes（PbCO0 3 ,Pb（CO3）2-2- ） are important, while hydroxide complexes dom- inate Pb speciation under more alkaline conditions. Other potential inorganic ligands to form lead comple- xes, such as NH3, F- ,Br- , S2-x- , NaPbCI0 3 ,NaPbC1;- and S2O2-3- , are insignificant under general geological conditions. Carboxylate and amino acids are most important organisms to form lead-organic complexes, es- pecially the former. Below 200℃, they can transport sufficient lead to form economic deposits. The miner- alizati

关 键 词：Pb络合物 相分离 迁移 沉淀 

分 类 号：P595[天文地球—地球化学]