中文摘要：

本文以北秦岭造山带华北陆块南缘被动陆缘火山裂谷（大洋？）盆地、早古生代岛弧-弧后盆地和晚古生代岛弧-蛇绿杂岩等构造相带为研究重点,综合利用同位素年代学、古生物年代学、岩石学、岩石地球化学和同位素地球化学等实测数据,系统研究和探讨了北秦岭造山带被动陆缘大洋扩张向俯冲增生造山转换的时限。研究显示：华北陆块南缘由晚新元古代大洋扩张作用转化为板块俯冲作用的转换时限为早奥陶世,约472Ma左右。北秦岭造山带在古生代期间至少存在两期板块俯冲增生造山作用,时代上向南变新,空间上向南向洋内迁移。两次俯冲增生造山作用分别构筑了北秦岭造山带早古生代岛弧-弧后盆地和晚古生代岛弧-俯冲杂岩两条构造相带。

英文摘要：

This study examines the tectonic affinities and geochronology of three tectonic facies in the north Qinling orogenic belt, the volcanic rift or oceanic basin on the south margin of the north China block, early Paleozoic island arc-backarc basin assembledge, and late Palezoic island arc-subduction-related opiolitic melange, respectively, using integrated field observations, biochronologic, geochemical, isotopic, SHRIMP and LA-ICP-Ms zircon U-Pb analyses. The results in the study show that transformation from sea-floor spreading on the south margin of the north China block to subduction resulting in the arc-basin system occuured in the early Ordovician, ca 472 ± 11 Ma, and there were two events of subductionaccretion orogeny developed in the north Qinling orogenic belt during the Paleozoic. Subduction migrated southward to the ocean from the early to late Paleozoic.