吉林省海沟金矿成矿时代及成矿动力学背景

发布时间：2018-05-30 13:09

本文选题：海沟金矿 + 矿床成因　；参考：《吉林大学》2017年硕士论文

【摘要】：海沟金矿位于吉林省延边朝鲜族自治州安图县两江镇,在大地构造位置上属于华北板块北缘东段的夹皮沟—海沟金矿带的东南端,东北侧毗邻兴蒙造山带。研究区太古宙时期属于强烈活动的花岗—绿岩带,此后经历了古生代的古亚洲洋构造域和中生代的太平洋构造域的构造、岩浆活动叠加和改造。海沟金矿位于呈NW向分布的清茶馆—白水滩断裂带和呈NE向分布的集安—松江断裂带(又称两江断裂带)的交汇部位。海沟金矿矿区内出露的地质体主要为中元古界色洛河群变质岩系、海西期海沟二长岩—二长花岗岩、燕山期石人沟黑云母二长花岗岩、大海沟辉长闪长岩以及不同走向的闪长玢岩、正长闪长斑岩、辉绿岩等脉岩。海沟金矿主要产于海沟岩体之中,已发现50余条金矿脉。金矿脉(体)主要受断裂构造控制,其中NE-NNE的断裂构造是最主要的控矿、容矿构造,NE-NNE向展布的28#、38#、43#脉带和NW向展布的33#脉带是海沟金矿最主要的生产矿脉。矿化类型以含金石英脉为主,蚀变岩型金矿化较少,主要分布在矿脉的深部和边部。含金石英脉型金矿石的矿石矿物以自然金、黄铁矿、黄铜矿、方铅矿、闪锌矿、辉钼矿为主,脉石矿物则以石英、碳酸盐矿物为主。深部矿体中辉钼矿的含量增高。主要围岩蚀变类型有包括钾化、硅化、黄铁矿化、绢英岩化和高岭土化、绿泥石化和绿帘石化及碳酸盐化,其中以钾化和硅化最为显著,金矿化与硅化和绢英岩化关系最密切。成矿可划分为5个阶段,即暗红色细粒石英—赤铁矿—沥青铀矿阶段、白色脉石英—钾长石阶段、灰色脉石英—黄铁矿阶段、烟灰色石英—多金属硫化物阶段、石英—方解石—黄铁矿阶段。气液包裹体研究表明,海沟金矿成矿流体总体上属于co2-h2o-nacl体系,具有中温、中低盐度(早期少量高盐度)的特点。硫、铅同位素分析表明成矿物质来源于地幔或以壳幔混源为主。海沟金矿产于晚古生代花岗质岩中,应属于与中基性岩体及脉岩有关的中温岩浆热液型金矿床,与典型的造山型金矿有一定差别。海沟二长岩—二长花岗岩相对富集rb、ba、k等大离子亲石元素(lile),相对亏损nb、p、ti等高场强元素(hfse),sr同位素初始比值(87sr/86sr)i为0.705656~0.705837,εnd(t)值为-10.42~-8.62,两阶段nd亏损地幔模式年龄tdm2为1.84ga~1.99ga,206pb/204pb值为17.2195~17.4301,207pb/204pb值为15.4659~15.5212,208pb/204pb值为37.1721~37.6601。总体上属于古生代古亚洲洋消减作用形成的高钾钙碱性i型花岗岩,并具有壳幔混源的特点。石人沟黑云母二长花岗岩相对富集rb、ba、k等大离子亲石元素(lile),相对亏损nb、p、ti等高场强元素(hfse),sr同位素初始比值(87sr/86sr)i为0.70695,εnd(t)值为-13.1,两阶段nd亏损地幔模式年龄tdm2为2.06ga,206pb/204pb值为17.5380,207pb/204pb值为15.5240,208pb/204pb值为37.7980。总体上属于中生代太平洋板块向欧亚板块俯冲作用形成的i型大陆弧花岗岩类,并具有壳幔混源的特点。大海沟辉长闪长岩相对富集rb、ba、k、sr、hf等大离子亲石元素(lile)以及th、u等放射性元素,相对亏损nb、p、ti等高场强元素(hfse),sr同位素初始比值(87sr/86sr)i为0.70465~0.70450,εnd(t)值为3.8~4.3,两阶段nd亏损地幔模式年龄tdm2为586ma~623ma,206pb/204pb值为18.5586~18.6337,207pb/204pb值为15.5861~15.5858,208pb/204pb值为38.6164~38.6651。形成于燕山晚期由挤压造山向伸展环境转变的时代,岩体物质来源于地幔,并受到地壳物质的混染。锆石u-pb同位素测年表明海沟岩体的成岩年龄为326.1±2.5ma,石人沟岩体的成岩时代为169.7±1.3ma,大海沟岩体成岩时代为132.6±0.8ma。与金矿成矿关系密切的闪长玢岩的成岩年龄为128±12ma、正长闪长斑岩以及成矿前—成矿期辉绿岩的成岩年龄分别是132.4±1.5ma和131.5±0.5ma。综合分析认为海沟金矿的成矿年龄可被限定在132.6~128ma之间。根据与海沟金矿有关的岩浆岩体的研究,结合矿区成矿地质事件分析,认为海沟金矿的成矿动力学背景为太平洋板块向欧亚板块俯冲条件下陆下软流圈地幔上涌、地幔岩石圈拆沉、减薄,所导致的强烈构造、岩浆和热液活动。
[Abstract]:The hitou gold mine is located in Liangjiang Town, Antu County, Yanbian, Jilin province. It belongs to the southeast end of the jacket - hinggou gold belt in the eastern part of the north margin of the North China plate, and the northeast side is adjacent to the Xingmeng belt. The Archean period belongs to the granite greenstone belt, which is a strong activity in the Archean period. After that, the Paleozoic Gu Yazhou was experienced. The tectonics of the Pacific tectonic domain and the Mesozoic Pacific tectonic domain, the superposition and transformation of magmatic activity. The Gigu gold deposit is located in the NW distribution of the Qing tea house white water beach fault zone and the Ji'an Songjiang fault zone (also known as the Liangjiang fault zone). The geological body in the Hai Gou Gold Mine is mainly the Middle Proterozoic salad. The metamorphic rock system of the river group, the Heisi trench two long granite, the two feldspar granite, the Yanshan phase of the Heigu black mica two granite, the gutterage diorite and different diorite porphyrite, the long diorite and the diabase, the Heigu gold deposit is mainly produced in the gully rock, and more than 50 gold veins have been found. The gold vein (body) is mainly broken. Crack structure control, in which the fracture structure of NE-NNE is the most important ore control, the ore bearing structure, the 28#, 38#, 43# vein and NW direction of the distributed 33# vein belt are the most important production veins in the NE-NNE. The mineralization type is mainly composed of gold and stone quartz veins, and the altered rock type gold mineralization is less, mainly distributed in the deep and edge veins of the vein. The ore minerals of the gold ore are mainly natural gold, pyrite, chalcopyrite, galena, sphalerite, and molybdenite. The gangue minerals are mainly quartz and carbonate minerals. The content of Molybdenite in the deep orebodies increases. The main types of rock alteration include potassium, silicification, Huang Tie mineralization, sericite and KAOLINIZATION, green and chlorinization and epidote. And carbonation and carbonation, of which potassium and silicification are most significant, gold mineralization is most closely related to silicification and sericite. The mineralization can be divided into 5 stages: dark red fine quartz - hematite - Bituminous stage, white vein quartz - potassium feldspar stage, gray vein quartz - pyrite stage, smoke gray quartz - polymetallic sulfide stage In the phase of quartz calcite pyrite, the study of gas-liquid inclusions shows that the metallogenic fluid of the Hai Gou Gold deposit belongs to the co2-h2o-nacl system in general, with the characteristics of middle and low salinity (early small amount of high salinity). The analysis of sulfur and lead isotopes indicates that the metallogenic material is derived from the mantle or the mixed source of crust and mantle. The gold deposit in the trench is produced in the late Paleozoic granite. In the rock, we should belong to medium temperature magmatic hydrothermal gold deposits related to medium basic rock mass and vein rock, which are different from typical orogenic gold deposits. The two long rock and two granites in the trench are relatively rich in Rb, Ba, K and other large ion lithophilic elements (lile), relative to the loss of Nb, P, Ti and other high field elements (HFSE), and the initial ratio of Sr isotopes (87sr/86sr) I is 0.705 656~0.705837, the value of epsilon Nd (T) is -10.42~-8.62, the two stage nd loss mantle model age tdm2 is 1.84ga~1.99ga, 206pb/204pb value is 17.2195~17.4301207pb/204pb value of 15.4659~15.5212208pb/204pb value is the high potassium calcium alkaline I type granite which belongs to the Paleozoic Paleozoic Paleozoic subduction, and has the crust and mantle mixture. The characteristics of the source are that the two feldspar granites are relatively rich in Rb, Ba, K and other large ionic stone elements (lile), relative to the loss of Nb, P, Ti and other high field elements (HFSE), the initial Sr isotope ratio (87sr/86sr) I is 0.70695, and the two stage of the two stage of the loss of mantle model age is 15.. The 5240208pb/204pb value is 37.7980. generally belonging to the I type continental arc granitoids formed by the subduction of the Mesozoic Pacific plate to the Eurasian plate, and has the characteristics of the mixed source of the crust and mantle. The long diorite of the sea gully long diorite is relatively rich in Rb, Ba, K, Sr, HF and other large ionic stone elements (lile), th, and u. The initial ratio of the strong element (HFSE), the initial ratio of Sr isotopes (87sr/86sr) I is 0.70465~0.70450, the value of the epsilon Nd (T) is 3.8~4.3, the two stage nd depleted mantle model age tdm2 is 586ma~623ma, and the 206pb/204pb value is formed at the late Yanshan from the extrusion orogeny to the extension environment. The rock mass originates from the mantle and is contaminated by the crust material in the time of change. The zircon U-Pb isotope dating shows that the age of the diagenesis of the trench rock mass is 326.1 + 2.5mA, the age of the diagenesis of the stone man gully rock is 169.7 + 1.3mA, and the diorite porphyrite age of 132.6 + 0.8ma. with the gold mineralization in the great trench rock age is 128. The age of the diagenesis of the normal long diorite porphyry and the pre metallogenic phase of the metallogenic phase of diabase is 132.4 + 1.5mA and 131.5 + 0.5ma.. The metallogenic age of the gutting gold deposit can be limited to 132.6~128ma. According to the study of the magmatic rock mass related to the gutage gold mine and the analysis of the metallogenic geological events in the mining area, it is considered that the gutting gold deposit The metallogenic dynamics background is that the Pacific plate subducted under subduction of the Eurasian plate, the subcontinental asthenosphere mantle upwelling, the mantle lithosphere delamination and thinning, resulting in strong structure, magma and hydrothermal activity.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P618.51

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