西太平洋海山玄武岩等离子体质谱分析及其地质意义

海山玄武岩记录着海山演化以及相关深部过程的重要信息。对西太平洋戈沃罗夫平顶海山、牛郎平顶海山、阿诺德平顶海山、斯科尔尼亚科瓦平顶海山、戈尔金平顶海山、麦克唐奈平顶海山、令仪海山、徐福平顶海山玄武岩进行岩石学和等离子体质谱测试分析,结果表明:研究区玄武岩多呈杏仁状、气孔-杏仁状、块状构造,斑状结构。岩石主要由斑晶、基质组成。斑晶的矿物成份主要为斜长石、橄榄石和单斜辉石。基质的矿物成份主要为斜长石、橄榄石、单斜辉石和玻璃质等。不同海山玄武岩的稀土配分模式以及稀土参数均反映了洋岛玄武岩的典型特征,表明了研究区海山是一组属于多热点成因的典型板内火山型海山,可能受过了多期次的区内断裂岩浆活动的影响。

Plasma Mass Spectrometry of Sea Mountain Basalts in the Western Pacific and Its Geological Significance

Seamount basalts recorded important information of seamount and deep evolution p rocess.Through the analysis of petrology and REE geochemical characteristics o f Govorov Guyot,Niulang Guyot,Arnold Guyot,Skornyakova Guyot,Gordin Guyo t,McDonnell Guyot,Lingyi Seamount,Xufu Seamounts basalts in the western Pacific,it shows that basalts in study area have amygdaloidal,fumarolic-amy gdaloidal and porphyritic texture.Rocks are mainly composed of phenocrysts and matrix.Mineral composition of phenocrysts is mainly plagioclase,olivine and clinopyroxene.Mineral composition of matrix is plagioclase,olivine,clinop yroxene and glassy etc.REE patterns and parameters of each sea mountain basalt s reflect the typical characteristics of oceanic island basalts.It indicates t hat the seamount in study area is a typical volcanic seamount in plate caused by multiple hotspots.At the same time,it may have been influenced by multi-st age fault and magmatic activity.