CAJ | 학술논문

为了确定在祁连托莱牧场一带新发现的中-新元古代火山岩的形成时代及岩石类型,并对其构造环境进行分析探讨。采取野外实地调查,并结合Sm-Nd等时线年龄测定、岩石学、岩石化学、岩石地球化学等方面的成果,进行综合分析研究。结果表明,新发现的中-新元古代火山岩由单一的玄武岩组成,呈夹层透镜体或构造岩块近东西向赋存于新划分的中-新元古代托勒片岩岩组中,Sm-Nd等时线年龄（950±53）Ma;岩石具斑状结构,基质具变余间粒结构,为铝过饱和型（A l2O3〉K2O＋Na2O＋CaO）岩石,属拉斑玄武岩系列;稀土、微量元素特征证明,其具有岛弧拉斑玄武岩和N-MORB的双重地球化学特征;同位素143Nd/144Nd=0.512 61～0.511 845,εNd（t）为-2.39。反映出火山岩浆源于偏基性的壳幔混合区,是陆缘裂谷的产物。
위료학정재기련탁래목장일대신발현적중-신원고대화산암적형성시대급암석류형,병대기구조배경진행분석탐토。채취야외실지조사,병결합Sm-Nd등시선년령측정、암석학、암석화학、암석지구화학등방면적성과,진행종합분석연구。결과표명,신발현적중-신원고대화산암유단일적현무암조성,정협층투경체혹구조암괴근동서향부존우신화분적중-신원고대탁륵편암암조중,Sm-Nd등시선년령（950±53）Ma;암석구반상결구,기질구변여간립결구,위려과포화형（A l2O3〉K2O＋Na2O＋CaO）암석,속랍반현무암계렬;희토、미량원소특정증명,기구유도호랍반현무암화N-MORB적쌍중지구화학특정;동위소143Nd/144Nd=0.512 61～0.511 845,εNd（t）위-2.39。반영출화산암장원우편기성적각만혼합구,시륙연렬곡적산물。
Field investigation was integrated with methods of Sm-Nd isochron age,lithology,lithochemistry and lithogeochemistry to determine the formation age and rock types of newly discovered volcanic rocks from a single basalt with Middle Proterozoic-Neoproterozoic in Tuole ranch area of Qilian,Qinghai,and to analyze its tectonic setting.The volcanic rocks with laminated lenses Or structure blocks occurred in the EW schist formation with Middle Proterozoic-Neoproterozoic,and with porphyritic texture and matrix with variable odd grain structure.The Sm-Nd isochron age is about 950±53Ma,and belongs to tholeiitic series with excess saturated aluminum of rock（Al2O3K2O＋Na2O＋CaO）.Its isotope 143Nd/144Nd=0.51261-0.511845,εNd（t） is-2.39.From the above,we have conclusion that magma derived from lower crust of partial mafic,and was the product of continental margin rift.