南辽河群斜长角闪岩的地球化学特征及地质意义:以三家子地区为例

基于详细的野外地质调查,对南辽河群下部里尔峪组斜长角闪岩进行了岩相学和地球化学研究。岩相学研究表明,南辽河群下部里尔峪组斜长角闪岩属于正变质岩。地球化学研究显示,这些斜长角闪岩原岩属于高铁拉斑玄武岩系列(Nb/Y=0.16~0.4),SiO_2含量为47.27%~50.68%,具有较低的TiO_2含量(0.92%~1.61%),亏损高场强元素(Nb、Ta、Zr、Hf等),表明其原岩形成于岛弧或活动大陆边缘,而非前人所说的大陆裂谷。综合岩相学和地球化学特征,初步认为其岩石成因与活动大陆边缘有关。

Geochemical characteristics of amphibolite of South Liaohe Group and their geological significance: a case study of Sanjiazi area

On the basis of detailed field geological survey, the authors undertook petrographic and geochemical analysis of the amphibolites in Lieryu Formation of lower South Liaohe Group. Petrographic studies show that the amphibolites in Lieryu Formation are orthometamorphite. Geochemical data indicates that the amphibolites belong to high Fe tholeiitic series (Nb/Y=0.16~0.40), with the content of SiO2 of 47.27%~50.68%, and low TiO2 content of 0.92%~1.61%. They are depleted in high field strength elements such as Nb, Ta, Zr and Hf, indicating that their original rocks were formed in an island arc or active continental margin, rather than the continental rift defined by previous studies. Integrating petrographic and geochemical characteristics, it is preliminarily concluded that the petrogenesis is related to the active continental margin.