摘要
内蒙古东乌旗北部地区白音高老组流纹质晶屑凝灰岩锆石SHRIMP测年结果显示火山岩年龄为(121.9±2.4) Ma,属早白垩世;岩石地球化学数据指示火山岩属高钾钙碱性系列,具有偏铝质特征;岩石总体富集大离子亲石元素Rb、Th、U、K,亏损Ba、Sr及高场强元素Nb、Ta、Zr、Ti,Hf。轻稀土相对富集,重稀土相对亏损,具较大的Eu异常(δEu=0.19~0.48)。综合研究表明,区内早白垩世白音高老组火山岩具有A2型岩浆岩的特征,应该是太平洋板块西北向俯冲后地壳伸展的产物。
The Baiyingaol Formation in the north area of East Ujimqin Banner,Inner Mongolia consists of mainly acid volcanic rocks.Zircon SHRIMP dating of rhyolitc tuff with crystals in BaiyingaolaoFormation shows that the age of Baiyingaolao formation volcanic rocks is 121.9±2.4Ma,which belongs to Early Cretaceous volcanic product.The geochemical characteristics of Baiyingaolao formation show that they have high-K cale alkaline rocks,and have weak aluminous characteristics.The rocks are obviously rich in Rb,Th,U,K,and poor in Ba and Sr,as well as HFSE of Nb,Ta,Zr,Ti and Hf.LREE are relative richer than HREE.The factional distillation of HREE shows that Eu have obvious superior negative anomaly(SEu average are between O.19 and O.48)Comprehensive researches indicate that Baiyingaolao formation volcanic rocks have the characteristics of A2-type granites and should be the result of stretching setting that related to the subduction of Pacific Plate during Early Cretaceous.
作者
赵鸿燕
邱庆伦
李鹏飞
关小荣
李丛
吕际根
ZHAO Hong-yan;QIU Qing-lun;Li Peng-fei;GUAN Xiao-rong;LI Cong;LV Ji-gen(Henan Academy of Territorial Spatial Survey and Planning,Zhengzhou 450053,China;Henan Academy of Geology,Zhengzhou 450001,China)
出处
《甘肃地质》
2024年第1期1-9,共9页
Gansu Geology
基金
中国地质调查局内蒙古东乌旗北部塔尔根敖包边防连等8幅1:5万区域地质调查项目(1212010881219)。
关键词
白音高老组
SHRIMP年龄
地球化学特征
构造环境
早白垩世
东乌旗
Baiyingaolao Formation
SHRIMP U-Pb dating
geochemical characteristics
tectonic setting
Early Cretaceous
East Ujimqin Banner
