陕西凤县二里河喷流沉积型铅锌矿床的地质地球化学证据

通过实地地质调查和取样测试,对二里河铅锌矿床进行标型矿物微量元素、围岩稀土元素地球化学特征、流体包裹体特征分析。结果表明:二里河铅锌矿床具有海底热水喷流沉积矿床一般地质特征,多期(华力西期+印支期)构造运动和幅度较大的裂陷发育史为大量矿质的喷流和聚集提供了十分有利的导矿和容矿构造条件。标型矿物微量元素地球化学特征显示:闪锌矿明显富集Cd((6493.74～7225.68)×10^-6),贫Sb、As,黄铁矿w(S)与w(Se)比值为23443.48～250284.36,w(Co)与w(Ni)比值为3.47～104.10,指示矿床具热水沉积特征,而黄铁矿w(Fe)/(w(S)+w(As))为0.87～1.52,表明该矿为浅部成因矿床;流体包裹体特征、围岩和闪锌矿稀土元素显著亏损Eu、Ce,指示二里河铅锌矿床可能具有喷流沉积型矿床远源矿化特征;log(δCe)为-0.04～0.04,表明二里河铅锌矿床围岩在还原环境下成岩;石英流体包裹体均一温度及闪锌矿成分指示的温度范围(215℃～333℃)特征表明该矿床为中温矿床。综上所述,二里河铅锌矿床可能为相对远离喷流口的喷流沉积型浅层中温层状矿床。

Geological and Geochemical Evidence of the Erlihe SEDEX Pb-Zn Deposit in Fengxian,Shaanxi

Based on the geologic survey and sampling test, characteristics of the typomorphic mineral trace element, wall rock rare earth elements geochemistry and fluid inclusion for Erlihe Pb-Zn Deposit were analyzed. The results showed that the Erlihe Pb-Zn Deposit had the general geological features of a submarine exhalative sedimentary deposit; the multi-phase tectonic movement of the Indo-Variscan period and the large-scale development of fractured surface provided a favorable structural condition for mineralization by erupting and aggregating a large number of minerals. Characteristics of the typomorphic mineral trace element showed that sphalerite was rich in Cd((6 493.74-7 225.68)×10^-6)and poor in Sb and As, pyrite w(S)/w(Se)and w(Co)/w(Ni)were 23 443.48-250 284.36 and 3.47-104.10 respectively, the deposit was hot brine sedimentary; pyrite w(Fe)/(w(S)+w(As))(0.87-1.52)suggested the deposit originated from shallow; characteristics of fluid inclusions and rare earth elements(dramatically depleted in Eu and Ce in wall rock and sphalerite)probably hint distal mineralization of SEDEX in medium temperature; log(δCe)(-0.04-0.04)displays an anoxic environment for wall rock diagenesis; the homogeneous temperature of quartz fluid inclusion and temperature interval of sphalerite components(215 ℃-333 ℃)showed the deposit was in medium temperature. In general, Erlihe Pb-Zn Deposit is possibly a type of superficial medium temperature strata-bound SEDEX deposit, relatively far away from the vent.