摘要
为厘定德能铜多金属矿床侵入岩时代,查明岩石成因,本文利用LA-ICP-MS技术对德能铜多金属矿床石英闪长玢岩锆石进行了U-Th-Pb同位素测定,分析了岩石地球化学和Sr-Nd-Pb同位素。结果表明,石英闪长玢岩形成于早白垩世126.6±2.2~127.5±2.2Ma。岩石硅含量中等(平均58.58%),富碱(ALK平均6.53%),为高钾钙碱性花岗岩。稀土元素球粒陨石配分模式图右倾,(La/Yb)N为4.64~6.18。大离子亲石元素Rb、Th、K、Pb、Zr和Hf等富集,高场强元素Nb、Ta、P、Ti等亏损。206 Pb/204 Pb为18.629~18.771,207 Pb/204 Pb为15.690~15.738,208Pb/204 Pb为39.188~39.435。(87 Sr/86 Sr)i为0.709215~0.710463,(143 Nd/144 Nd)i为0.512044~0.512093,εNd(t)为-8.40^-7.45,TDM2为1524~1602Ma。上述分析结果表明,石英闪长玢岩为I型花岗岩,具岛弧岩浆活动特征,是向南俯冲的班公湖-怒江洋壳脱水,导致地幔楔发生熔融,幔源物质上涌引起中元古代下地壳物质发生部分熔融的产物。
In order to obtain the age and genesis of quartz diorite-porphyrites of the Deneng copper polymetallic deposit,U-Th-Pb measurement was carried out on zircons from quartz diorite-porphyrites using LA-ICP-MS technique,geochemistry and Sr-Nd-Pb isotopes.Zircon U-Pb dating yielded the ages of 126.6±2.2Ma to 127.5±2.2Ma,which corresponds to the crystallization age of quartz diorite-porphyrites.The quartz diorite-porphyrites belong to the high-K calc-alkaline series and are characterized by middle SiO2and highobvious negative Eu anomaly（Eu=0.66-0.74）.They are also enriched in large ion lithophile elements（LILEs e.g.,Rb,Th,K,Pb,Zr and Hf）and depleted in high field strength elements（HFSEs e.g.,0.709215to 0.710463,andMa.On the basis of the results above,we can conclude that the quartz diorite-porphyrites should be I-type granite with typical feature of arc magmatism.The genesis can be attributed to the southward subduction of the Bangong-Nujiang Ocean seafloor,which dehydrated and caused the partical melting of mantle wedge.The upwelling of mantle materials led to the partial melting of Meso-proterozoic lower crust and formed the magma of the Deneng quartz dioriteporphyrites.
作者
于玉帅
高原
杨竹森
田世洪
周云
张炜强
YU Yushuai;GAO Yuan;YANG Zhusen;TIAN Shihong;ZHOU Yun;ZHANG Weiqiang(East China University of Technology,Nanchang,330013,China;Wuhan Center of Geological Survey,CGS,Wuhan,430205,China;Research Center of Granitic Diagenesis and Mineralization,CGS,Wuhan,430205;J iang xi Institute of Geology Survey,Nanchang,330030,China;Institute of Mineral Resources,CAGS,Beijing 100037,China)
出处
《地质学报》
EI
CAS
CSCD
北大核心
2018年第7期1458-1473,共16页
Acta Geologica Sinica
基金
国家自然科学基金项目(编号41503040)
国家重点研发计划项目(编号2016YFC0600306)资助的成果
