南祁连北缘东段晚奥陶世构造演化:多藏角闪辉长岩U-Pb年代学、岩石地球化学和矿物化学证据
发布时间：2018-08-05 15:22
【摘要】：为约束多藏角闪辉长岩的岩石成因和南祁连北缘东段晚奥陶世的构造演化,对多藏角闪辉长岩进行了LA-ICP-MS锆石U-Pb年代学、岩石地球化学和矿物化学分析。结果表明,角闪辉长岩中锆石具条痕状吸收和高的Th/U比值(0.37~1.16),暗示其岩浆成因。岩浆锆石的206Pb/238 U定年结果为(444±3)Ma,表明多藏角闪辉长岩形成于晚奥陶世,两组捕获锆石的年龄为520 Ma和484 Ma,代表早期的岩浆事件。多藏岩体具相对低的SiO_2含量(51.68%~55.66%)和高的MgO(4.48%~7.37%)、TiO_2(1.01%~1.24%)、FeO~T(7.99%~8.72%)含量以及高的Mg#值(53~63);LREEs相对富集、HREEs相对亏损,(La/Yb)N=4.03~7.89,具有弱的Eu异常(δEu=0.78~1.16),富集LILEs(Rb、Ba、K)、亏损HFSEs(Nb、Ta),具Sr、P、Ti元素的亏损。结合矿物化学分析表明,南祁连北缘东段多藏角闪辉长岩起源于受俯冲流体交代的富集岩石圈地幔物质的部分熔融,形成于洋-洋汇聚向洋-陆碰撞转换背景下俯冲大洋板片断离后的伸展构造环境。
[Abstract]:In order to constrain the petrogenesis of multi-reservoir hornblende gabbro and the late Ordovician tectonic evolution in the eastern part of the northern margin of South Qilian, LA-ICP-MS zircon U-Pb chronology, petrogeochemical and mineralogical analysis were carried out for the multireservoir hornblende gabbro. The results show that the zircon in hornblende gabbro has strip-like absorption and high Th/U ratio (0.37 ~ 1.16), indicating its magmatic origin. The 206Pb/238 U dating of magmatic zircon is (444 卤3) Ma, which indicates that the multi-reservoir amphibolite was formed in the late Ordovician. The ages of two sets of zircon traps are 520Ma and 484Ma. which represent the early magmatic events. 澶氳棌宀╀綋鍏风浉瀵逛綆鐨凷iO_2鍚噺(51.68%~55.66%)鍜岄珮鐨凪gO(4.48%~7.37%),TiO_2(1.01%~1.24%),FeO~T(7.99%~8.72%)鍚噺浠ュ強楂樼殑Mg#鍊，
本文编号：2166198
[Abstract]:In order to constrain the petrogenesis of multi-reservoir hornblende gabbro and the late Ordovician tectonic evolution in the eastern part of the northern margin of South Qilian, LA-ICP-MS zircon U-Pb chronology, petrogeochemical and mineralogical analysis were carried out for the multireservoir hornblende gabbro. The results show that the zircon in hornblende gabbro has strip-like absorption and high Th/U ratio (0.37 ~ 1.16), indicating its magmatic origin. The 206Pb/238 U dating of magmatic zircon is (444 卤3) Ma, which indicates that the multi-reservoir amphibolite was formed in the late Ordovician. The ages of two sets of zircon traps are 520Ma and 484Ma. which represent the early magmatic events. 澶氳棌宀╀綋鍏风浉瀵逛綆鐨凷iO_2鍚噺(51.68%~55.66%)鍜岄珮鐨凪gO(4.48%~7.37%),TiO_2(1.01%~1.24%),FeO~T(7.99%~8.72%)鍚噺浠ュ強楂樼殑Mg#鍊，
本文编号：2166198
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