【作者】 刘虎；

【导师】 王金荣；

【作者基本信息】 兰州大学 ， 矿物学、岩石学、矿床学， 2013， 硕士

【摘要】 阳山金矿处于西秦岭造山南亚带,为我国重要的金成矿带,下泥盆统三河口组是主要赋矿地层。本文在野外地质调查和实验室分析测试的基础上,利用岩相学、岩石地球化学、流体包裹体等研究方法,对研究区花岗岩及其成矿作用进行了系统地研究,取得了如下成果和认识：1、阳山金矿的花岗岩类岩石的Si02含量70.41%～74.89%,平均72.00%；TiO2平均含量0.24%；A1203平均含量15.13%； MgO含量O.68%；CaO含量平均1.61%；Alk(Na20+K20)含量2.39%～6.78%,平均3.70%,其中Na2O0.11％～3.95%,平均0.63%,K2O2.25％～3.92%,平均3.07%；A/CNK:1.14～2.74,平均2.03,为过铝质。微量元素中Rb、K、La、Nb、Hf、Tb(?)目对富集,Ba、P、Nb.Sr.Ti相对亏损。研究区岩浆岩稀土总量∑REE57.2～90.9×10-6(平均82.97×10-6),LREE富集,(La/Yb)N=8.92～24.51,稀土元素发生不同程度的分馏,轻、重稀土元素之间也有一定分馏；中等的负Eu异常(Eu／Eu*=0.66～0.90,平均0.79),指示岩浆作用过程中,斜长石有一定程度晶出,或源区有斜长石残留；岩石属高钾钙碱性系列,源于地壳物质部分熔融,形成于造山环境。2、花岗岩LA-ICP-MS锆石U-Pb年龄研究结果表明：1)花岗斑岩锆石年龄具新太古代到侏罗纪的谱系；2)斜长花岗斑岩从古元古代到白垩纪谱系；3)蚀变花岗细晶岩从中元古代到志留纪谱系的特点。结合区域地质特征及研究区的花岗岩类侵入于泥盆系可以推断,阳山地区存在印支期和燕山期两期的花岗岩类岩石,花岗斑岩形成于侏罗纪(J),斜长花岗斑岩形成于白垩纪(K),而老于泥盆纪的锆石是花岗岩浆形成及侵入过程捕获结晶基底和褶皱基底的锆石,指示该区存在前寒武结晶基底。3、区内流体包裹体发育中等、类型简单,多为富液相包裹体(L-V),少量为纯液相(L),包裹体成分主要为CO2,属碳-水体系,另有少量CO。宿主矿物以石英为主。流体包裹体在石英中随机分散分布,部分地段集合成群,少量次生包裹体沿裂隙呈带状分布,发育程度从上往下减弱、从西往东增强,指示成矿流体为自下而上运移。流体包裹体均一温度位于中低温区,存在两个峰值,与盐度对应。研究结果也显示,不同温度盐度的流体发生混合,温度压力的变化以及冷却、稀释及PH、EH值的改变,是矿质发生沉淀的重要因素。成矿流体来源主要为天水,有来自岩浆热液成分的加入,指示温度压力突变导致金大量富集于快速沉淀的黄铁矿中,推断阳山金矿深部找矿前景较大。更多还原

【Abstract】 Yangshan gold deposit in west qinling mountain belt in South Asia, for the important gold metallogenic belt in China. In this paper, on the basis of field geological investigation and laboratory analysis test, by lithology, rock geochemistry, fluid inclusion study, obtained the following results:1, Granite rock in the Yangshan gold deposit has the SiO2content of70.41%～74.89%, average72.00%; TiO2average content0.24%; A12O3average content is15.13%; CaO average content is1.61%; Alk (Na2O+K2O) content is2.39%～6.78%, average3.70%, including Na2O content of0.11%～3.95%, average0.63%, K2O2.25%～3.92%, average3.07%; A/CNK:1.142.74with average of2.03, could be assign to peraluminous. The trace elements generally show Ba、P、Nb、S、Ti losse, and Rb、K、La、Nb、Hf、Tb rich. The total igneous rock REE content is higher he studied area and less volatility (∑REE57.2-90.9×10-6, average82.97×10-6). LREE rich and (La/Yb) N8.92～24.51. REE shows different degree of fractionation, LREE and HREE also appears certain degree of fractionation; Showing relatively medium negative Eu (Eu/Eu*=0.66-0.90, average of0.79), which indicates plagioclase has a certain degree crystallization or left from the source rock during the magmatism process. The rock belongs to high potassium calcic-alkline series, due to the crust material partially melting and formed in orogenic environment.2, granite LA-ICP-MS zircon U-Pb age research results show that:1) granite porphyry zircon age spectrum of new archean to the Jurassic;2) inclined long granite porphyry zircon ages from paleoproterozoic to cretaceous spectrum;3) altered granitic aplite zircon age from the proterozoic to the characteristics of the pedigree of the silurian. Combined with regional geological features and granite type of intrusion in the devonian system in the study area can be deduced that yangshan area phase exist indosinian and yanshan period two granite rocks, granite porphyry formed in the Jurassic (J), plagioclase granite porphyry formed in the cretaceous (K), and the indo-chinese epoch before the zircon is granitic magma formation and intrusion process captured crystalline basement and the palaeozoic fold basement of zircon, indicating existence before the Cambrian in the area of crystalline basement. 3, fluid inclusions in the growth medium, simple type, mostly rich liquid inclusions (L V), a small amount of pure liquid (L), the composition of inclusions are mainly CO2, carbon-water system, and a small amount of CO. Host minerals mainly quartz. Fluid inclusions in quartz randomly scattered distribution, sections of the collection. Fluid inclusions, uniform temperature in the low temperature area, there are two peaks, and salinity. Results also show that different salinity of fluid mixing, temperature changes in temperature and pressure and cooling, the change of dilution and PH and EH value, is an important factor in mineral precipitation occurs. Source of ore-forming fluid mainly for tianshui, have joined from magmatic hydrothermal constituents, concluded that yangshan gold deep prospecting prospect is larger.更多还原