Mafic dykes from Øksfjord, Seiland Igneous Province, northern Norway: geochemistry and palaeotectonic significance
Mafic dykes from Øksfjord, Seiland Igneous Province, northern Norway: geochemistry and palaeotectonic significance
复制标题
挪威北部塞兰火成岩省 Øksfjord 的镁铁质岩脉：地球化学和古构造意义
作者：
H. Reginiussen;E. Ravna;K. Berglund
摘要Øksfjord-Langfjord地区的基性岩脉是在塞兰火成岩省漫长的构造岩浆演化过程中不同阶段侵入的。野外关系、岩石学和地球化学表明，该区存在4代碱性玄武岩岩脉和1代碱性煌斑岩岩脉。整个岩脉组具有与板块内大地构造环境形成相一致的地球化学特征。微量元素表明碱玄武岩脉具有洋岛玄武岩的亲缘性，表明其源为岩石圈下地幔。资料支持塞兰火成岩省与裂谷有关的起源。塞兰火成岩省（300英里）岩浆活动的寿命很难用传统的地幔柱框架来解释。认为本省间歇岩浆活动以容许性岩浆活动为主，受岩石圈构造控制。
Abstract Mafic dykes from the Øksfjord-Langfjord area were intruded at different stages during the prolonged tectonomagmatic evolution of the Seiland Igneous Province. Field relations, petrography and geochemistry indicate the presence of four dyke generations with alkali basalt composition and one generation of alkaline lamprophyres. The entire dyke suite has geochemical signatures consistent with formation in a within-plate geotectonic environment. Trace elements indicate that the alkali basalt dykes have OIB (ocean island basalt) affinities and we suggest a sublithospheric mantle source. The data support a rift-related origin for the Seiland Igneous Province. Longevity of magmatism in the Seiland Igneous Province (300 m.y.) is difficult to explain within a conventional mantle plume framework. Instead, it is proposed that the intermittent magmatism in the province was predominantly permissive and controlled by lithosphere structure.