【摘要】 地球化学研究表明:北秦岭榴辉岩原岩属于拉斑玄武岩系列,岩石的Nb/La=0.68～0.92,Ce/Nb=2.11～3.62,Th/Yb=0.42～1.00,Ti/Zr=75.26～125.84,显示源区具有N-MORB的特征;岩石Nb含量9～13μg/g,Zr/Y值为4.24～6.92,同时明显富Ti和Fe,又显示了OIB的特征,因此岩石源区应是N-MORB和OIB两个端元的混合。结合地质资料综合分析,认为北秦岭榴辉岩原岩可能是洋盆中的海山玄武岩,具有洋壳性质,洋壳被消减俯冲到下地壳或地幔深处,经高压变质形成榴辉岩。更多还原

【Abstract】 The protolith of eclogites in north Qinling belongs to tholeiitic basalt.The ratios of Nb/La,Ce/Nb,Th/Yb and Ti/Zr of the eclogites are 0.68～0.92,2.11～3.62,0.42～1.00 and 75.26～125.84, respectively,showing the characteristics of NMORB.However,Their Nb contents of 9～13 μg/g and Zr/Y ratios of 4.24～6.92,together with the enrichment of Ti and Fe,show the affinity of OIB.Therefore the protolith of the eclogites is probably derivation from the source with the mixture of NMORB and OIB members.Based on regionally geological information,the protolith of eclogites is possibly seamount basalt in the oceanic basin,and is of the component of oceanic crust.The basalts subducted downward to the low crust or the mantle,and metamorphized to eclogite at highpressure.更多还原