摘要
武功山造山带位于华夏地块与扬子地块碰撞缝合带南侧,记录了新元古代以来的多次构造运动。本文对其中的黑云母二长花岗岩和二云母二长花岗岩进行了全面的矿物学、岩石地球化学、锆石U-Pb同位素年代学及Lu—Hf同位素研究。LA-ICP-MS锆石U-Pb同位素年代学研究指示武功山黑云母二长花岗岩和二云母二长花岗岩结晶于早志留世(441.6~442.2 Ma)。武功山早志留世花岗岩具有富硅(SiO_(2)含量为67.43%~73.06%)、富碱(Na_(2)O+K_(2)O含量为6.47%~8.46%)、贫钙(CaO=0.78%~2.64%)、贫镁(MgO=0.46%~1.61%)等特征,为强过铝质高钾钙碱性花岗岩(A/CNK=1.09~1.35)。同时,岩相学和地球化学指示岩石属于亚碱性系列,分异程度较低,ΣREE较低,轻重稀土分异程度较高,为S型花岗岩且岩浆源区物相为角闪石+斜长石+石榴子石。结合花岗岩锆石fLu/Hf值均小于-0.9,εHf(t)均为负值(-6.7到-4.8),指示岩浆来源于古元古代古老陆壳物质,形成于陆内造山构造背景下,为武功山地区对武夷—云开造山运动的响应。
Objectives:This paper provided Petrography,geochemical characteristics,LA-ICP-MA zircon U-Pb age,and zircon Lu—Hf isotopes of Early Paleozoic granite in the Wugong Mountain area,South China.The formation age,genesis,and geological significance of granites are discussed.Methods:Based on the field work,through the microscopic observation,the whole rock chemical analysis,the LA-ICP-MS zircon U-Pb isotopic chronology,and the LA-ICP-MS zircon Lu—Hf isotopes of granites.Results:The zircons of Wugong Mountain granite have good euhedral degree and developed oscillatory belts,showing the characteristics of magmatic origin.Zircon LA-ICP-MS U-Pb isotopic chronology shows that the granites in the Wugong Mountain area were formed at 441.6~442.2Ma and were the products of the Early Silurian orogeny.The rocks are rich in silicon(SiO_(2)=67.43%~73.06%),alkali(Na_(2)O+K_(2)O=6.47%~8.46%),and poor in calcium(CaO=0.78%~2.64%),magnesium(MgO=0.46%~1.61%).Aluminum saturation index(A/CNK=1.09~1.35).It is enriched in large ion lithophile elements such as Rb,K,Th and U,and relatively depleted in high field strength elements such as Nb and Ti.The ratio of light and heavy rare earth elements(La/Yb)N=7.91~12.69,with a high degree of differentiation and moderate—weak negative Eu anomaly(δEu=0.50~0.86).The rare earth distribution curves are right-leaning,indicating the characteristics of S-type granite.Zircon fLu/Hf values of the Wugong Mountain granite are all less than-0.9,andεHf(t)are all negative.Conclusions:Collectively,it is suggested that the granite belongs to strong peraluminous high-potassium calc-alkaline granite.It is S-type granite,and the magmatic facies is hornblende+plagioclase+garnet.The Wugong Mountain granite was formed in the Early Silurian,and the test results are relatively concentrated,revealing that the early Paleozoic granite in the Wugong Mountain area was formed in a relatively short time.The zircon Lu—Hf isotopic characteristics indicate that the magma source area is neoproterozoic continental crust mater
作者
张垚垚
刘凯
何庆成
童珏
邓岳飞
余成华
孙军亮
余廷溪
郭骏瀚
王书训
ZHANG Yaoyao;LIU Kai;HE Qingcheng;TONG Jue;DENG Yuefei;YU Chenghua;SUN Junliang;YU Tingxi;GUO Junhan;WANG Shuxun(Chinese Academy of Geological Sciences,Beijing,100037;China University of Geosciences(Beijing),Beijing,100083;The Fourth Geological Brigade of Jiangxi Geological Bureau,Pingxiang,Jiangxi,337000;CIGIS(CHINA)LIMITED,Beijing,100007;Shenzhen Investigation and Research Institute CO.,LTD,Shenzhen,Guangdong,518000)
出处
《地质论评》
CAS
CSCD
北大核心
2023年第3期1004-1020,共17页
Geological Review
基金
中国地质调查项目(编号:DD20221677-2、DD20201165)
中央财政基本科研业务费项目(编号:JKY202004、JKY202011)
江西省重点研发计划项目(编号:20203BBG72W011)
江西省地质局科技研究项目(编号:2021AA07)的成果。
关键词
武功山
早古生代
地球化学
Lu—Hf同位素
地质意义
Wugong Mountain
Early Paleozoic
geochemistry
Lu—Hf isotopes
geological significance
