【摘要】 辽东前任屯角闪岩中锆石的阴极发光图像显示其具均匀的吸收条带,具有镁铁质超镁铁质岩中锆石的特征。锆石的SHRIMPU_Pb分析结果主要集中在谐和线上117～143Ma之间,206Pb/238U的平均年龄值为128.6±5.1Ma(204Pb校正的结果),表明前任屯角闪岩岩体的形成时间为早白垩世。研究区内早白垩世镁铁质超镁铁质岩石和花岗质岩石的共存,即双峰式岩浆作用的存在,表明华北克拉通东部早白垩世时期强烈伸展环境的存在,同时暗示中生代岩石圈地幔减薄达到了峰期。更多还原

【Abstract】 The zircons from Qianrentun amphibolite in eastern Liaoning show an uniform absorbing band in cathodoluminescence （CL） images, being of characteristics of zircons in the mafic_ultramafic intusives. SHRIMP U_Pb dating results of the zircons are mainly distributed between the concordia ages of 117～143 Ma with a weighted mean （）²⁰⁶Pb/²³⁸U age of 128.6±5.1 Ma (²⁰⁴Pb corrected), indicating that the amphibolite was formed in Early Cretaceous. The coexistence of Early Cretaceous mafic_ultramafic igneous rocks and granitoids in eastern Liaoning, i.e. the presence of the bimodal magmatism, suggests that a strong extensional environment existed in the eastern part of the North China Craton in Early Cretaceous and that the thinning of lithospheric mantle reached its culmination in that period.更多还原