Rb-Sr isotope age of Niuquanzi ophiolite and its tectonic significance in Beishan district, Gansu

The ophiolite of early Paleozoic time of Beishan in Gansu,affected by the Aljin NE left-lateral strick-slip fault,is divided in to three sections which are Baiyun shan-Xichangjing, Tongchangkou-Niuquanzi and Baiyu shan-Hong liuhe section.Niuquanzi ophiolite,developed all units of ophiolite and resembling eastern Xichangjing and western Hongliuhe ophiolite belonging to the type of oceanic crustop hiolite,is also the type of oceanic crustop hiolite. Its Rb-Sr isotope age is 463±18 Ma(middle Ordovician-early stage of late Ordoviaian),the same as age of Rediolaria in band of Xichangjing ophiolite and that of Hongliuhe ophiolite hasn't been determined.Recovering the tectonic,this three secsions are one ophiolite zone of early Paleozoic.And it is a stylolitic zone between Tarim and kazakh stan missif in Early Paleozoic.