摘要
通过对所有已发表的辽西义县组火山岩数据进行系统的主、微量元素和同位素分析，发现义县组火山岩以中基性为主，其上部层位中酸性组分增多。其高的Mg值和埃达克质特征并不是原始岩浆本身的性质，不能作为下地壳拆沉作用的有力证据。义县组火山岩的基性部分主要来自于受洋壳俯冲作用改造过的岩石圈地幔，并存在与古老下地壳来源的熔体不同程度的混合作用。因此，义县组火山岩是岩浆混合作用的产物而非下地壳拆沉作用的产物。底侵的下地壳也参与了义县组火山岩的形成，但软流圈组分的参与有限。
The authors, based on the systematics of all the published major, trace elemental and isotopic data of volcanic lavas from the Yixian Formation, western Liaoning Province, found that the volcanic lavas of the Yixian Formation are composed dominantly of marie-intermediate components with the increasing intermediate-acidic components in the upper sequence. Their high Mg values and adakitic geochemical characteristics are not the primary features of the initial magma, and thus cannot be regarded as the powerful evidence for the existence of lower crust delamination in the region. The marie components of the Yixian Formation were originally derived from the lithospheric mantle, which were previously modified by the subducted oceanic crust. The mixing of marie magrna with ancient lower crust-derived magma to a certain degree produced the various volcanic lavas of the Yixian Formation. Therefore, volcanic lavas of the Yixian Formation are the products of magma mixing rather than lower crust delamination. Basaltic underplated lower crust was involved in the origin of these volcanic lavas, with little and limited contribution of the asthenosphere.
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2008年第1期37-48,共12页
Acta Petrologica Sinica
基金
国家自然科学基金委大陆动力学群体项目(40721062)
中国科学院知识创新工程重要方向项目(KZCX2-YW-103)
百人计划资助成果
关键词
辽西
义县组
火山岩
岩浆混合作用
岩石圈伸展
Western Liaoning Province, Yixian Formation, Volcanic lava, Magma mixing, Lithosphere extension
