北京大学学报（自然科学版）2025，Vol.61Issue(3)：508-524,17.DOI:10.13209/j.0479-8023.2025.024
北阿尔金850 Ma大陆溢流玄武岩对地幔柱活动的启示
The 850 Ma Continental Flood Basalts in North Altun Block and Their Implications for Mantle Plume Activity
摘要
Abstract
This paper reports the layered mafic volcanic rocks formed in the Hongliuquan area of the North Altyn region at 843 Ma.This suite of volcanic rocks has relatively high TiO2(1.18%-2.06%),low Zr/Hf(23.28-29.28)and low Nb/Ta(4.20-12.99),showing the trace element characteristics of E-MORB/OIB,like the typical low-Ti basalts in large igneous provinces.The analysis results of major and trace elements in the entire rock show that the magma of the basic rock has undergone a low degree of partial melting(<10%)of the asthenosphere source of garnet(<2%),and has been subject to varying degrees of crustal mixing during the uplift process.The occurrence,geochemical characteristics,age data and high mantle potential temperature(Tp=1479℃)of the northern Aljin layered basic volcanic rock indicate that this basic volcanic rock is a continental overflow basalt(CFB)originated from the Neoproterozoic mantle plume.Combined with the extended background magmatic activity developed in the region during the same period(850-750 Ma),we believe that the northern Alkinic volcanic rocks record the earliest magmatic activity during the supercontinent rifting process.In the Neoproterozoic era,it was discovered that the magmatic activities of Alkin and those of the Qilian,Chaibei Margin,Eastern Kunlun,South China and Qinling Mountains all had the diagenological characteristics of an intracontinental rift valley environment,which indicates that they are related to the mantle plume activities at 850-800 Ma.It further indicates that the formation of the Northern Altyn volcanic rock mass is closely related to the beginning of the rifting of the Rodinia supercontinent at approximately 850 Ma.关键词
大陆溢流玄武岩/地幔柱/新元古代/北阿尔金/罗迪尼亚超大陆Key words
continental flood basalts/mantle plume/Neoproterozoic/North Altyn/Rodinia supercontinent引用本文复制引用
冯迪,李艳广,宋述光..北阿尔金850 Ma大陆溢流玄武岩对地幔柱活动的启示[J].北京大学学报（自然科学版）,2025,61(3):508-524,17.基金项目
国家自然科学基金(91955202)资助 （91955202）
