摘要
辽东半岛岫岩王家堡子地区位于胶-辽-吉造山/活动带中段。本文对该区内的二长花岗岩与花岗斑岩(杨家堡岩体与石庙沟岩体)进行了U-Pb年代学与地球化学特征研究,并探讨了其地质意义。结果表明:杨家堡岩体与石庙沟岩体侵位年龄分别为(127.4±0.57)Ma和(123±1.6)Ma,年代为早白垩世。早白垩世杨家堡岩体明显的Nb、Ta异常,Ta/Th值较低,应与板块的俯冲有关,且与高山提出由拆沉作用形成的岩浆地球化学特征一致,即LREE与HREE分异明显、高Sr/Y、Th/U、Mg^(#),低Lu/Hf值,表明岩浆形成与由板块俯冲导致的拆沉作用有关。早白垩世石庙沟岩体A/CNK=1.05~1.11,为铝质A型花岗岩,形成于长英质地壳的脱水部分熔融。早白垩世杨家堡岩体为准铝质或弱过铝质、中-高钾钙碱性系列的I型花岗岩,具有活动大陆边缘花岗岩的岩石组合特征。综上所述,辽东地区燕山期岩浆活动应与古太平洋板块俯冲碰撞有关,由碰撞产生的挤压造山作用结束于123±1.6Ma,开始进入碰撞后拉伸的构造环境,开启了岩石圈减薄的序章。
Wangjiapuzi area in Xiuyan county of the Liaodong Peninsula is located in the middle section of the Jiao-Liao-Ji(Shandong-Liaoning-Jilin)orogenic/active belt.In this paper,the U-Pb chronology and geochemical characteristics of monzogranite and granite porphyry(Yangjiapu pluton and Shimiaogou pluton)in this area are studied,and their geological significances are discussed.The results show that the emplacement ages of the Yangjiapu pluton and the Shimiaogou pluton are(127.4±0.57 Ma)Ma and(123±1.6)Ma respectively in the Early Cretaceous.The Yangjiapuzi plutons of the Early Cretaceous have obvious Nb and Ta anomalies,and the Ta/Th values are low,which are related to the subduction of the plate,and is consistent with the magma geochemistry characteristics formed by the delamination proposed by Gao Shan,i.e.,the obvious differentiation between LREE and HREE,high Sr/Y,Th/U,Mg^(#),and low Lu/Hf,indicating that the magma formation is related to the delamination caused by plate subduction.The Shimiaogou pluton of the Early Cretaceous with A/CNK=1.05-1.11 is an aluminum A-type granite,which was formed in the melting of the dehydrated part of the felsic crust.The Yangjiapaozi pluton of the Early Cretaceous is quasi-aluminous or weakly peraluminous,and belongs to the medium-high potassium calc-alkaline series I-type granites,which have the rock association characteristics of active continental margin granites.In summary,the Yanshanian magmatic activity in the Liaodong area should be related to the subduction and collision of the paleo-Pacific plate.The compressional orogeny caused by the collision ended at 123±1.6 Ma,and it began to enter the tectonic environment of post-collision extension,which opened the preface of lithosphere thinning.
作者
何俐
李琛
He Li;Li Chen(Liaoning Chemical Geological Exploration Institute Co.,Ltd.,Jinzhou 121000,Liaoning,China)
出处
《化工矿产地质》
CAS
2022年第2期109-121,共13页
Geology of Chemical Minerals
基金
中国地质调查局“辽东吉南成矿带永吉-凤城地区地质矿产调查”子项目“辽宁1∶5万王家堡子(K51E022013)、苏子沟(K51E022014)、黄花甸子(K51E021014)、岫岩县(K51E023014)幅区域地质矿产调查”(DD20160049-8)。
关键词
早白垩世
花岗岩
锆石
U-PB
测年
地球化学
构造转换
岫岩王家堡子地区
Early Cretaceous
Granite
Zircon U-Pb dating
Geochemistry
Tectonic transformation
Wangjiapuzi area in Xiuyan county
