摘要
取自小赛什腾山的3个岩浆岩样品的锆石LA-ICP-MS U-Pb测年结果给出了437±10 Ma与487±14 Ma（XSST01）、390.8±9.1 Ma（XSST02）、400.1±7.9 Ma与445.8±10 Ma（XSST03）5组206Pb/238U平均年龄结果,这表明小赛什腾山地区存在470-480 Ma、440-450 Ma和390-400 Ma三期古生代花岗质岩浆侵入旋回,更正了小赛什腾山地区花岗岩均形成于海西期的认识？将本次给出的年代学数据与柴北缘构造带古生代花岗质岩浆作用年代学格架进行对比,结果表明,小赛什腾山地区490-400 Ma花岗岩侵位时间、期次与整个柴北缘构造带其他地区基本一致,这些年代学数据为证实小赛什腾山是柴北缘构造带的重要组成部分提供了重要证据？同时认为,奥陶纪初期（470-480 Ma）岩浆岩的形成与柴北缘洋洋壳向北俯冲有关,奥陶纪末期（440-450 Ma）的花岗岩形成于同造山陆-陆碰撞环境,早泥盆世（390-400 Ma）花岗岩与俯冲-碰撞晚期岩石圈拆沉有关,初步厘定了约490-400 Ma小赛什腾山一带的大地构造演化格架？
Zircon U-Pb dating was conducted for three magmatic rock samples from Xiaosaishiteng Mountain area, which yielded five average zircon U-Pb ages of 437±10 Ma, 487±14 Ma（XSST01）, 390.8±9.1Ma（XSST02）, 400.1±7.9 Ma and 445.8±10 Ma（XSST03）. These ages reflect three periods of Paleozoic granitoid magma intrusion epoch in 470―480 Ma, 440―450 Ma, 390―400 Ma and prove the granite in Xiaosaishiteng Mountain area formed at the Hercynian. By contrast of the age data in this paper and the phases of Paleozoic granitoid magmatism in structural belt of the north Qaidam Basin, the result that reveals the granitiod magma intrusion time of stage in 490―400 Ma is consistent with other areas of northern margin of the Qaidam Basin. These age＇s data play a major role on proving that the Xiaosaishiteng Mountain is a part of structural belt of the north Qaidam Basin. Meanwhile, it is held that magmatic rocks of the Early Ordovician period（470―480 Ma） are concerned with oceanic crust subduction to north on the north margin of the Qaidam Basin, granite of the Late Ordovician period（440―450 Ma） formed in syn-orogenic continental collision regime and granite of the Early Devonian（390―400 Ma） is related to lithosphere delamination formed in late subduction-collision environment. Till then, framework of tectonic Evolution during about 490―400 Ma in Xiaosaishiteng Mountain area was preliminarily confirmed.
出处
《矿物学报》
CAS
CSCD
北大核心
2016年第1期119-124,共6页
Acta Mineralogica Sinica
基金
国土资源地调项目(资[2014]03-025-002
12120113040000-3)
关键词
小赛什腾山
古生代
花岗岩
锆石U-PB定年
地质意义
Xiaosaishiteng mountain
paleozoic
granite
zircon U-Pb dating
geological significance
