【作者】 张志辉；

【导师】 张达；

【作者基本信息】 中国地质大学（北京） ， 矿物学、岩石学、矿床学， 2009， 硕士

【摘要】 本论文研究以现代成矿作用、成矿预测理论为指导,对焦冲金硫矿矿区地层、构造、岩浆岩及焦冲金硫矿成矿流体特征等与成矿有关的信息进行综合分析,结合野外实地调查,开展焦冲金硫矿成矿规律及成矿预测工作,圈定预测远景区,为该区找矿工作的部署提供依据。对焦冲金硫矿成矿规律研究表明,焦冲金硫矿矿床多与燕山期造山运动有关。该区的金硫矿矿床,明显地受断裂构造控制,含矿断裂为北东向和北北东向。焦冲金硫矿成矿流体的来源为岩浆热液并从岩石中萃取成矿物质,形成成矿溶液,最后形成矿床,通过对矿物包裹体研究表明,该矿床的三个成矿阶段的成矿温度区间分别为410℃～440℃、320℃～350℃和260℃～320℃,即从早期的石英-硫化物阶段到晚期的方解石热液阶段成矿温度呈现逐渐减低的趋势。焦冲金硫矿成矿深度为1.5Km,成矿压力400×105 Pa。焦冲金硫矿床含金矿物主要为硫化物,硫化物的δ³⁴S平均值相当于热液的总δ³⁴S值,为4.16‰,该值反映了矿石中的硫总体具有深源硫的特征,即硫主要来源于深源岩浆,极少量可能来自于地层中的海水硫酸盐。矿石铅的μ值（9.38～9.49）未出现大幅度的波动,可以指示其壳源特征且与岩浆活动关系密切,反应出该种铅来自下部地壳或者上地幔,铅同位素演化基本处于封闭体系,且在成矿过程中基本未受地壳物质的混染。矿区侵入的辉石二长闪长岩、花岗闪长斑岩具有陆壳沉积岩重熔派生的花岗岩类岩石特征。结合矿区地质作用背景及成矿年代学研究,认为可能燕山中晚期中国东部大陆壳大面积减薄,导致深部幔源熔融岩浆上升,直接底侵到陆壳沉积岩下,使得陆壳沉积岩发生部分熔融,进而派生出本区中酸性的花岗闪长斑岩岩浆。同时,幔源岩浆进一步分异,向过碱性方向演化,形成了本区辉石二长闪长岩岩浆。根据焦冲矿区侵入岩LA—ICP—MS锆石U—Pb年龄分析结果和解释,辉石二长闪长岩结晶年龄206Pb/238U加权平均年龄为122±1Ma,比花岗闪长斑岩结晶年龄206Pb/238U加权平均年龄128±2 Ma要晚。该区岩浆岩形成顺序应为花岗闪长斑岩-辉石二长闪长岩。综合研究认为焦冲金硫矿是青山背斜与岩浆活动共同作用形成的中高温热液充填～交代型矿床,成矿深度为中深成,矿体形成以充填为主,交代次之。更多还原

【Abstract】 This article, guided by modern theories of mineralization and metallogenic prognosis, makes a comprehensive analysis on the information about the stratum, structure, magmatic rocks and characteristics of fluorite mineralization fluid of the the Jiaochong Au-S ore deposit area. Combined with field investigation and the results of work on metallogenic regularity and metallogenic prognosis of the Jiaochong Au-S ore deposit, it enloses a prospect forecast area and provides guidance for the arrangement of the exploration in this area.Studies on the metallogenic regularity of the Jiaochong Au-s ore deposit show that Au-s ore deposit has a lot to do with Yanshanian orogenic movement. Obviously controlled by fault structure, the ore-bearing faults in this area run in E-W and N-S direction. The Jiaochong Au-S ore deposit mineralization liquid comes from the magmatic thermal fluid, extracting mineralizing substance from the rocks, and eventually produces the deposit. Research on the mineral fluid inclusions indicate that the temperature is divided by 3 ranges: 410℃～440℃、320℃～350℃和260℃～320℃,showing a decreasing trend of the temperature from the Quartz-sulfide stage earlier to calcite thermal fluid stage. The depth of the mineralization of Jiaochong Au-S ore deposit is 1.5 Km, and the mineralization pressure is 0.4 Gpa. The S-containing minerals including in the Jiaochong Au-S ore deposit are mostly sulfide. The averagement value of theδ³⁴S of the sulfide which equates the sum value of theδ³⁴S of the thermal fluid is 4.16‰, The value indicates that the sulfur of the ores has the characteristics of the deep-resource sulfur, which means that the sulfur mostly comes from the deep magma and little may come from the marine sulfate in the stratum. Theμvalue of the lead in the ores never shows the wave in big scales, indicating their crustal characteristics and the close association with the magmatic activity. The value also shows this kind of lead comes from the lower crust or the upper mantle, lead isotope basically evolved in the enclosed system and hasn’t been contaminated by the crustal substance.The intrusive pyroxene monzodiorite and granodiorite porphyry have the characteristics of granite deriving from the crustal sedimentary rocks remelting. Combing with the ore-geological function background and ore-forming chronological study, it’s considered that in the mid-late stage of the Yanshan the continental crust in the East China thinned, causing the up-raising of deep mantle-derived magma and directly intrude beneath the crustal sedimentary rocks which makes the crustal sedimentary rocks partly melting and derives to the mid-acid granodiorite porphyry magma. Meanwhile, mantle-derived magma differentiates to the alkaline direction, producing the pyroxene monzodiorite magma in this section. According to the analysis and interpreter of the LA-ICP-MS zircon U-Pb dating of the intrusive rocks, the 206Pb/238U average age of the pyroxene monzodiorite’s crystalization is 122±1Ma, which is latter than that of the granodiorite porphyry, exactly 128±2 Ma.This dating is controversial to the primitive petrogenetic age in this district. The sequence of the magmatic rocks’crystaliztion should be granodiorite poryphyry-pyroxene monzodiorite.After the comprehensive study, it’s considered that Jiaochong Au-S ore deposit is the moderate-to-high temperature thermal filled-alteration ore deposit affected by both Qinggshan anticline and the magma activity. The ore-forming depth is mesogenetic, and the type of the ores are filled primarily and alteration secondarily.更多还原