新疆东天山红云滩铁矿床地质特征与矿床成因研究

发布时间：2018-06-13 02:22

本文选题：东天山 + 觉罗塔格　；参考：《中国地质大学(北京)》2015年硕士论文

【摘要】：近年来,作为重要铁矿类型的火山岩型铁矿是国内学术研究的热点。新疆东天山造山带觉罗塔格地块的阿奇山-雅满苏铁矿带位于准噶尔板块与塔里木板块拼合部位,发育众多大-中-小型铁矿床。对于这些赋存于火山岩地层中的铁矿床的整体研究滞后,矿床成因、成矿作用过程、区域成矿规律及机制尚不清楚。因此,本文选取该铁矿带西段的红云滩铁矿床,开展深入的野外地质调查,运用电子探针、岩石地球化学、锆石U-Pb年代学、Hf同位素、流体包裹体测温及稳定同位素研究,对矿床的成矿地质特征、成矿大地构造背景、成矿物质来源、成矿时代等研究分析,从而对红云滩铁矿床成因取得了深入的认识:红云滩铁矿赋存于下石炭统雅满苏组火山岩中,矿体呈层状、似层状、透镜状产出,不位于侵入岩的接触带;矿石类型主要为块状、浸染状、条带状矿石,局部为角砾状、细脉状矿石;成矿演化经历了3个阶段:透辉石-石榴石矽卡岩阶段,磁铁矿-阳起石-透闪石-绿帘石-绿泥石退化蚀变阶段,石英-绿帘石-钠长石-钾长石-硫化物阶段。矿石矿物以磁铁矿为主,伴生少量黄铁矿和极少量黄铜矿;电子探针分析表明,磁铁矿总体具较低的Ti、Cr、V,微量组分含量与IOCG、与矽卡岩型铁矿中磁铁矿特征相近,Ti/V比值约1.02,表明是热液交代成因,且Ni含量很低,并非岩浆型和沉积成因特点;黄铁矿微量元素反映S/F比值多大于理论值,指示氧逸度和硫逸度较低的高温热液环境,Co/Ni比多1,成矿与火山-岩浆热液的作用有关。早期矽卡岩主要为钙矽卡岩:石榴子石为钙铁榴石-钙铝榴石系列,以钙铁榴石为主;辉石主要为透辉石-钙铁辉石系列,以透辉石为主,还有钙铁辉石;角闪石主要为阳起石、铁阳起石、少量铁闪石;绿泥石主要为铁镁绿帘石、铁绿泥石;绿帘石从退化蚀变阶段到晚阶段均有发育,早阶段绿帘石相对富铁,Fe/(Fe+Al)比值相对高。钠化-钾化发育于围岩矿化蚀变外带和石英硫化物阶段,钠长石(Ab58.06-99.23An0.72-40.91Or0.04-1.04)、钾长石(Or95.56-98.44Ab1.56-4.36 An0.00-0.07)。围岩蚀变广泛发育,从成矿早阶段到晚阶段显示蚀变分带特征,且矽卡岩与铁矿化关系密切。矿区内石英二长闪长岩、花岗闪长岩、黑云母二长花岗岩、钾长花岗岩主量元素显示准铝质钙碱性花岗岩,稀土、微量元素特征,显示火山弧花岗岩特征。LA-ICP-MS锆石U-Pb测年获得石英二长闪长岩351.5±1.2Ma,黑云母二长花岗岩326.76±0.78Ma,钾长花岗岩297.36±0.51Ma。Hf同位素显示εHf(t)=4.5~14.4,且三者的二阶模式年龄tDM2均大于其锆石U-Pb年龄,岩浆物质可能来源于俯冲板片作用引起的下地壳物质的部分熔融。雅满苏组火山岩(石英角斑岩)属中-基性系列,化学成分属钙碱性系列,稀土和微量配分曲线显示,为陆缘弧火山岩的地球化学特征;LA-ICP-MS锆石U-Pb测年获得矿体顶板石英角斑岩324.1±3.1Ma。Hf同位素显示,εHf(t)=0.1~6.1,接近球粒陨石线,岩石源区为洋壳俯冲环境下,年轻地幔及下地壳物质部分熔融形成的岩浆,火山岩与侵入岩形成构造环境耦合。流体包裹体测温显示,矽卡岩阶段石榴石均一温度在550°C以上,盐度9.21~15.95wt%;退化蚀变阶段绿帘石和石英的均一温度峰值在240°C~330°C。晚期石英硫化物阶段方解石温度集中在200°C~220°C。流体温度和盐度呈降低趋势。氢、氧、硫同位素显示,石榴石平衡水的δ18O在6.5~9.7‰,显示成矿流体以岩浆水为主;绿帘石平衡水δ18O值为3.9~5.4‰,钾长石平衡水的δ18O为3.45~3.65‰,石英平衡水δ18O值为-2.3~0.2‰,显示成矿晚阶段有大气水的加入。磁铁矿的δ18O值为1.2~5‰,平均为3‰,表明铁质以岩浆来源为主。黄铁矿和黄铜矿的δ34S集中于-3.8~4.3‰(平均-0.7‰),具幔源硫特征。结合前人研究,成矿物质以岩浆来源为主,成矿流体主要来自岩浆热液,晚期有大气水或海水加入。参考前人区域成岩和成矿年代学研究成果,根据矿体顶板围岩石英角斑岩锆石U-Pb年龄324.1±3.1Ma,最晚期侵入岩钾长花岗岩297.36±0.51Ma年龄,限定红云滩铁矿床成矿在324~300Ma之间,晚石炭发生的铁成矿作用。综合本次研究工作和前人已取得成果,充分考虑成矿构造背景,并与区域上典型火山岩型铁矿对比,认为红云滩铁矿形成于晚石炭世火山-岩浆作用晚期,显示富铁流体交代-充填雅满苏组火山岩地层而成矿的多阶段特征,应属于为海相火山热液型铁矿床。
[Abstract]:In recent years, the volcanic type iron ore, which is an important type of iron ore, is a hot spot in the domestic academic research. The azqi aliman ore belt in the jagodagan block of the East Tianshan orogenic belt, Xinjiang, located in the joint part of the Junggar plate and the Tarim plate, developed a large number of large medium small iron deposits. The whole study is lagging behind, the genesis of the ore deposit, the process of mineralization and the regional metallogenic regularity and mechanism are not clear. Therefore, this paper selects the Hongyun beach iron deposit in the west section of the iron ore belt, and carries out an in-depth field geological survey, using electron probe, rock geochemistry, zircon U-Pb annual generation, Hf isotope, fluid inclusion temperature measurement and stable isotope research. The metallogenic geological features of the deposit, the metallogenic tectonic background, the source of metallogenic material and the metallogenic age have been studied and analyzed, and the cause of the genesis of the red cloud beach iron deposit is deeply understood. The ore types are mainly massive, disseminated, banded ore, partially breccia and fine vein ore; the metallogenic evolution has experienced 3 stages: the diopside - Garnet skarn stage, the magnetite - alimite - tremolite - epidote chlorite degradation stage, the quartz epidote albite - potassium feldspar - sulfide phase. The ore minerals are magnets Ore mainly, with a small amount of pyrite and very small chalcopyrite, electron probe analysis shows that magnetite has a lower Ti, Cr, V, trace component content and IOCG, which is similar to the magnetite in skarn type iron ore, and the Ti/V ratio is about 1.02, indicating that it is a hydrothermal metasomatism, and the Ni content is very low, not magmatic type and sedimentary origin; pyrite micro The quantity element reflects the S/F ratio which is more than the theoretical value, indicating the high temperature hydrothermal environment with lower oxygen fugacity and lower sulfur fugacity. The Co/Ni ratio is 1 more than that of the volcano magmatic hydrothermal solution. The early skarn is mainly calcilicate calcite: the garnet is a calcite, calcite series, mainly with calcite, and the pyroxene calcite pyroxene is mainly pyroxene. The series is mainly diopside and calcene pyroxene, and hornblende is mainly ascite, iron - Yang stone and a small amount of ferric amphibole. The chlorite is mainly iron and magnesium epidote, iron chlorite, and epidote is developed from the stage of degeneration and alteration to late stage. The early stage of epidote is relatively rich in iron, and the ratio of Fe/ (Fe+Al) is relatively high. The sodium and potassium mineralization is developed in the mineralization erosion of the surrounding rock. The altered outer zone and quartz sulfide phase, sodium feldspar (Ab58.06-99.23An0.72-40.91Or0.04-1.04) and potassium feldspar (Or95.56-98.44Ab1.56-4.36 An0.00-0.07). The alteration of the surrounding rock is widely developed, and the alteration zone is characterized by the alteration zone from the early stage to the late stage of the mineralization, and the skarn and iron ore are closely related. The quartz two diorite, the granodiorite and the black in the mining area. The main elements of the mica two granites show that the main elements of the potassium feldspar show the quasi al calc alkaline granites, rare earth and trace elements, showing that the.LA-ICP-MS zircon U-Pb dating of the volcanic arc granite obtained the quartz two diorite 351.5 + 1.2Ma, the black mica two granitic 326.76 + 0.78Ma, and the 297.36 + 0.51Ma.Hf isotopes of the potash granitic granite showing epsilon Hf (T) = =. 4.5~14.4, and the two order mode age of the three is larger than the U-Pb age of its zircon. The magma material may be derived from the partial melting of the lower crust material caused by the subduction plate action. The volcanic rock (quartz hornporphyry) in the Jan suzu formation is a medium basic series, and the chemical composition is a calc alkaline series. The rare earth and trace distribution curves show that it is a continental arc volcano. The geochemical characteristics of rock; LA-ICP-MS zircon U-Pb dating has obtained 324.1 + 3.1Ma.Hf isotopes of quartz angle porphyry of the orebody, and epsilon Hf (T) =0.1~6.1, close to the chondrite line, the source area of the rock is the magma formed by the partial melting of the young mantle and the lower crust material in the oceanic subduction environment, and the volcanic rock and the intrusive rock formed the tectonic environment coupled with the fluid. The temperature of the inclusions shows that the homogeneous temperature of garnet in the skarn stage is above 550 C, and the salinity is 9.21~15.95wt%; the peak value of the homogeneous temperature of epidote and quartz at the stage of degradation alteration is in the stage of the late quartz sulfide stage of 240 degrees C~330 C., the temperature of the calcite is concentrated at 200 [200] C. fluid temperature and salinity. Hydrogen, oxygen, and sulfur isotopes show that the temperature and salinity of the calcite are decreased. The delta 18O of the garnet balanced water is 6.5~9.7 per thousand, indicating that the ore-forming fluid is dominated by rock size water, and the delta 18O value of epidote equilibrium water is 3.9~5.4 per 1000, the delta 18O of the potassium feldspar equilibrium water is 3.45~3.65 per 1000 and the delta 18O value of the quartz balance water is -2.3~0.2 per 1000, indicating that the late stage of the mineralization has the addition of atmospheric water. The delta 18O value of the magnetite is 1.2~5 per thousand, with an average of 3 per thousand, indicating iron quality. The main source of magma is that the delta 34S of pyrite and chalcopyrite concentrates on -3.8~4.3 per thousand (average -0.7 per thousand) and has the characteristics of mantle derived sulfur. In combination with previous studies, the metallogenic material is mainly derived from magma source, and the ore-forming fluid mainly comes from magmatic hydrothermal fluid, and the late atmospheric water or seawater is added. The zircon U-Pb age of the quartzite porphyry in the roof surrounding rock is 324.1 + 3.1Ma, and the most late intrusive rock potassium feldspar is 297.36 + 0.51Ma age, and the iron mineralization of the Hongyun beach iron deposit is formed between 324~300Ma and Late Carboniferous. The comprehensive study and the previous achievements have been obtained, and the metallogenic tectonic setting is considered and the typical fire in the region is considered. Compared with the rock type iron ore, it is believed that Hongyun beach iron ore formed in Late Carboniferous volcano magmatism, showing the multi-stage metallogenic characteristics of the metasomatism of rich iron fluid and filling the jacousu formation, which should belong to the hydrothermal ore deposit of the marine volcano.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.31

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