摘要
北祁连山系内,分布着一套类型十分齐全的新元古代-早古生代海相火山岩系。包它括有大陆裂谷火山岩、洋脊-洋岛火山岩、岛弧火山岩、弧后盆地火山岩和陆缘被动裂谷火山岩。本文重点介绍北祁连山早古生代洋脊-洋岛火山岩和弧后盆地火山岩的岩石地球化学特点,并从地幔动力学角度探讨它们的岩石成因。这无疑对于深入了解地质历史古老增生板块边缘的火山作用有重要意义。
A sequence of Neoproterozoic-early Palaeozoic marine volcanic rocks with a full range types is distributed in the North Qilian Mountains. It includes continental rift volcanic rocks,mid-ocean ridge and ocean island volcanic rocks,island arc volcanic rocks,back-arc basin volcanic rocks and passive continental-margin rift volcanic rocks. This paper mainly introduces the petrogeochemical characteristics of the early Palaeozoic mid-ocean ridge-ocean island and back-arc basin volcanic rocks in the North Qilian Mountains are their petrogenesis is explored from the angle of mantle dynamics. The authors propose that the origin of mid-ocean ridge-ocean island volcanic magmas is mainly related to mixing and partial melting of two-layer mantle (with a source of N-MORB in the upper layer and an OIB source in the lower layer) under oceanic crust and that the source components of back-arc basin volcanic magma are complex, which may include depleted peridotite from the oceanic lithosphere, relatively fertile Iherzolite derived by the diapiric rise of the mantle plume and fluids from the subduction zone. These ideas are undoubtedly of crucial importance in the further understanding the volcanism taking place on older constructive plate margins in the geological record.
出处
《地质学报》
EI
CAS
CSCD
北大核心
1998年第4期301-312,共12页
Acta Geologica Sinica
基金
国家科技攻关计划(编号85-901)
关键词
洋脊-洋岛
火山岩
弧后盆地
火山作用
岩石成因
mid-ocean ridge-ocean island volcanic rocks
back-arc basin volcanic rocks
vol- canism
petrogenesis
North Qilian Mountains
