鄂西神农架群石槽河组火山岩地球化学特征及地质意义

Geochemical Characteristics and Geological Significance of Shicaohe Volcanic Rocks of Shennongjia Group in Western Hubei Province

在神农架群石槽河组中,发育有一套变玄武岩夹凝灰岩的火山岩组合,夹于上下两套碳酸盐岩之间。石槽河组火山岩Si O2在45.25%~53.70%之间,其中变玄武岩属于碱性系列,凝灰岩属于拉斑玄武系列。地球化学特征显示石槽河组火山岩具有板内碱性玄武岩特征,岩浆来源于软流圈,为格林威尔造山运动中俯冲碰撞后缘在大陆基础上拉张形成裂谷盆地的产物。

Meta-basalt and tuff, intercalated in the two carbonate rocks, are found in the Shicaohe volcanic rocks of Shennongjia group. The contents of SiO2 are 45.25 % -53.70%. The meta-basalt belongs to alkaline series, while the tuff belongs to tholeiitic basaltic series. The geological characteristics reveal the Shicaohe volcanic rocks are plate alkaline basalts. Their magma could be derived from the asthenosphere. They may form in the rift basin of continental tension,which is a product at the subduction collision trailing edge in Greenville orogenic event.