【摘要】 通过对大兴安岭北段塔木兰沟组玄武岩岩石学、地球化学及其形成的大地构造环境的综合研究发现,塔木兰沟组玄武岩具有拉斑玄武岩和碱性玄武岩的双重特征,Na2O-2<K2O;Eu无异常,La/Yb=35.7(平均);富集Ba、Sr、K,亏损Nb.岩浆的形成可能与裂谷作用有关.在这一构造-热事件中,推测该裂谷在上黑龙江地区陆壳减薄最大,呼中地区岩石圈减薄最大,根河地区陆壳、岩石圈减薄均较小.更多还原

【Abstract】 Study on the petrology,geochemistry and tectonic setting of the basalt from Tamulangou formation indicates that the basic volcanic rocks are geochemically similar to both tholeiitic basalt and alkali basalt,with Na2O-2< K2O,no negative Eu anomaly,La/Yb=35.7,rich Ba,Sr and K,and deficient Nb.The magma is probably generated by rifting.In such a thermal-tectonic event,it is speculated that the crust in Shangheilongjiang area and the lithosphere in Huzhong area were thinned greatly;while the lithosphere and the crust in Genhe area were slightly thinned.更多还原