地幔柱活动对克拉通岩石圈地幔的影响:西伯利亚克拉通地幔橄榄岩包体Sr-Nd-Hf同位素制约  

Effect of mantle plume activity on craton lithospheric mantle:Sr-Nd-Hf isotopic constraints of mantle peridotite xenoliths of Siberian Craton

作　　者：程哲 孙晶[1] CHENG Zhe;SUN Jing(College of Geosciences,China University of Petroleum,Beijing 102249,China)

机构地区：[1]中国石油大学(北京)地球科学学院,北京102249

出　　处：《世界地质》2023年第4期621-635,共15页World Geology

基　　金：国家自然科学青年基金项目(41602045)。

摘　　要：利用单矿物溶液法分析了Obnazhennaya金伯利岩中橄榄岩包体单矿物的Sr-Nd-Hf同位素组成,并且与Udachnaya金伯利岩中橄榄岩包体单矿物的Sr-Nd-Hf同位素组成进行了对比。结果显示,Obnazhennaya金伯利岩中橄榄岩包体单斜辉石具有亏损的Sr同位素组成和富集的Nd、Hf同位素组成。橄榄岩包体石榴子石的Sr-Nd-Hf同位素组成表现出原始的特征,没有受到交代作用的影响。通过对比Udachnaya和Obnazhennaya金伯利岩中地幔包体的特征和单斜辉石的二元混合模拟发现,Udachnaya金伯利岩中的地幔包体的Sr-Nd-Hf同位素组成更偏向于金伯利岩的特征,而与之相反,Obnazhennaya金伯利岩中的地幔包体的Sr-Nd-Hf同位素组成则位于金伯利岩和地幔柱溢流玄武岩之间,且更加偏向于溢流玄武岩的同位素特征。因此,地幔柱活动对西伯利亚克拉通岩石圈产生了影响,改变了其岩石圈地幔的同位素组成。The Sr-Nd-Hf isotopic compositions of minerals in peridotite xenoliths from the Obnazhennaya kimberlite are analyzed using solution method,and compared with those from Udachnaya kimberlite.The results show that the clinopyroxenes within peridotite xenolith in the Obnazhennaya kimberlite are depleted in Sr and enriched in Nd,Hf isotopic compositions.The Sr-Nd-Hf isotopic compositions of garnets from peridotite xenoliths in the Obnazhennaya kimberlite show primitive characteristics and are not affected by metasomatism.By comparing the characteristics of mantle xenoliths in Udachnaya and Obnazhennaya kimberlites and simulating binary mixing of clinopyroxenes,it is found that the Sr-Nd-Hf isotopic composition of mantle xenoliths in Udachnaya kimberlite is quite similar to the characteristics of the hosting kimberlite,while the Sr-Nd-Hf isotopic composition of mantle xenoliths in Obnazhennaya kimberlite is of the character between kimberlite and basalt related to mantle plume,which is more close to the isotopic characteristics of basalt lava flow.Therefore,the mantle plume activity has an impact on the Siberian Craton lithosphere,changing the isotopic composition of its lithospheric mantle.

关 键 词：SR-ND-HF同位素 地幔柱 橄榄岩包体 西伯利亚岩克拉通 

分 类 号：P597[天文地球—地球化学]