摘要
青海省都兰县果洛龙洼金矿床位于东昆仑造山带东段,昆中断裂南侧。矿床赋矿围岩是一套奥陶-志留系纳赤台群的浅变质火山沉积岩系。矿床受多级构造系统控制,东西向断裂是矿区的主用控矿断裂。矿化体类型主要是黄铁矿为主的硫化物石英脉,其次为硫化物蚀变岩型矿体。硫同位素测试数据显示,黄铁矿δ34S为0.2‰～3.88‰,方铅矿δ34S为-2.03‰～-5.95‰。含金石英脉中黄铁矿的206Pb/204Pb、207Pb/204Pb、208Pb/204Pb变化范围分别为18.057～18.135、15.524～15.585、37.962～38.110;方铅矿中变化范围为18.093～18.106、15.542～15.563、37.901～37.919。含矿石英脉成矿流体分析显示其液相成分相对富含K+、Na+、Ca2+、SO24-、NO23-离子,阳离子中一般Na+>K+>Ca2+>Mg2+;阴离子中SO42->Cl->F->NO23-;气相成分中除H2O为主要成分外,CO2含量也较高。围岩和石英脉矿体中黄铁矿稀土分析显示其∑LREE/∑HREE在3.49～28.17之间,(La/Sm)N=2.23～29.49,轻重稀土发生了强烈的分馏,具有轻稀土富集的特征;δEu变化在0.36～1.44之间,δCe在0.71～1.08之间,两者皆以弱负异常为主。黄铁矿微量元素分析显示大多数Co/Ni比值在0.63-3.8之间;Hf/Sm、Nd/La和Th/La值小于1。硫、铅同位素研究显示矿床的成矿流体来源于深部岩浆;成矿流体、稀土和微量元素研究表明矿床成矿温度为中高温-中低温,成矿流体是富Cl-和SO42-的深部岩浆热液,金以该类络合物形式运移。
The Guoluolongwa gold deposit is located in the eastern section of the East Kunlun orogenic belt,south of the Middle of Eastern Kunlun fault zone.It is controlled by multi-level structural systems,and main ore-controlling faults are of east-west trend.The Ordovician-Silurian Nachitai Group metamorphosed volcanic sedimentary rocks are the direct country rocks.The main type of mineralization is pyrite-dominated sulphide quartz vein and the subordinate one is sulphide altered rock type.The δ34S values of 6 pyrites separated of auriferous quartz veins show variations from 0.2‰ to 3.88‰,while galenas show variations from-2.03‰ to-5.95‰.The lead isotope compositions of sulfides from the gold ore are characterized by low radiogenic values and narrow ranges of ratios：18.057 to 18.135 for 206Pb/204Pb,15.524 to 15.585 for 207Pb/204Pb,and 37.901 to 37.919 for 208Pb/204Pb,respectively.Quartz ore-forming fluid analysis shows its liquid compositions are relatively rich in K＋,Na＋,Ca2＋,SO2-4,and NO2-3 ions,and usually Na＋ K＋Ca2＋Mg2＋in positive ions,SO2-4 Cl- F- NO2-3in negative ions;gaseous compositions are mainly H2O and CO2-rich.Pyrites rare earth elements （REE） and trace element analysis shows that the range of ∑LREE/∑HREE is 3.49～ 28.17,（La/Sm）N=2.23～29.49,indicating both light REE（LREE） and heavy REE（HREE） underwent intensely fractionation and characterized by LREE enrichment-type REE patterns.The variations of δEu and δCe are mainly 0.36～1.44,0.71～1.08,respectively,both of them exhibit weak negative anomalies.Most of samples’ Co/Ni ratios are between 0.63 and 3.8,and ratios Hf/Sm,Nd/La and Th/La are less than 1.Studies on the sulfur and the lead isotopes show that the ore-forming materials are mainly derived from the deep magma.Research on ore-forming fluids,REE and trace elements reveals that the ore-forming temperature is medium-high and medium-low temperature.Ore-forming hydrothermal is rich in Cl-and SO2-4ions,and the Au migrated in this type of complex.
出处
《地质与勘探》
CAS
CSCD
北大核心
2010年第5期931-941,共11页
Geology and Exploration
基金
国家十一五科技支撑计划重大项目:柴达木南北缘铜铅锌矿成矿规律及大型资源基地评价技术示范研究课题(编号:2006BAA01B06)
青海省地方地质勘查基金项目:"青海省都兰县果洛龙洼地区金矿成矿规律研究及找矿预测"资助
关键词
果洛龙洼
造山带
硫、铅同位素
成矿流体
微量元素
Guoluolongwa
orogenic belt
sulfur and lead isotopes
ore-forming fluid
trace elements
