【摘要】 通过对额尔古纳八卡地区酸性侵入岩进行LA-ICP-MS锆石U-Pb定年研究表明,八卡区内5个代表性的酸性侵入岩体中的锆石大部分为自形-半自形晶,显示其为岩浆成因锆石;岩浆作用集中于3个阶段。其包括:1)新元古代早期岩浆活动,正长花岗岩加权平均年龄为798 Ma±6Ma,其形成可能与Rodinia超大陆裂解的构造背景有关;2)晚二叠世—早三叠世的岩浆活动,岩石年龄介于238～267Ma,结合花岗岩特征,反映其形成于古亚洲洋闭合后的造山后环境;3)花岗岩的138Ma±1Ma、137Ma±2Ma岩体年龄显示了早白垩世岩浆作用的存在,该岩浆事件与蒙古-鄂霍茨克缝合带的演化有关。更多还原

【Abstract】 Zircons from the 5 representative acidic intrusive bodies in Baka area are generally idiomorphic or hypidiomorphic crystals from magma.Data of LA-ICP-MS zircon U-Pb dating of the acidic intrusive rocks are concentrated in 3 stages.The first stage is early Neoproterozoic orthoclase granite with the weighted average age of 798 Ma±6 Ma which is related to the geological event of disintegration of Rodinia supercontinent.The second stage is 242 to 265 Ma,the late Permian-Early Triassic period and the magmatism took place under the post-orogenic environment after the closure of the Paleo-Asian oceanaccording to characteristics of the granite.The third stage is is 138 Ma±1 Ma and 137 Ma±2 Ma corresponding to early Cretaceous Epoch related to the evolution of the Mongolian-Okhotsk suture zone.更多还原