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选取新疆东准噶尔北部青格里河下游一带乌图布拉克、阿热勒托别和哈旦逊岩体等具一定规模的3个代表性岩体,通过全岩Rb-Sr等时线同位素定年,确定了研究区内玛音鄂博断裂南侧花岗岩类的形成时代分别为(334.1±9.5)M a、(300±9)M a和(280±12)M a,其初始87Sr/86Sr比值分别为0.704 33、0.704 35和0.703 84。结果表明研究区内花岗岩分别形成于华力西中晚期的不同阶段。乌图布拉克岩体形成于早石炭世,为碰撞造山作用晚期的钙碱性花岗岩,可能是早泥盆世富Nb玄武岩部分熔融的产物;结合前人厘定的板块俯冲时间(408~376 M a),推测西伯利亚板块与哈萨克斯坦—准噶尔板块的碰撞时限为376~334 M a。阿热勒托别岩体形成于后碰撞拉张环境,可能是形成于岛弧环境的中基性火山岩部分熔融的产物;哈旦逊岩体虽然也形成于后碰撞拉张环境,但拉张程度更高,属于与岩浆底侵作用有关的花岗岩类。
Three representative rock masses with a certain scale, such as the Wutubulak, the Atheletobe and the Hudsonons in the lower part of the Qinggli River in the northern part of East Junggar, Xinjiang, were selected and isotopely determined by Rb-Sr isotope dating (334.1 ± 9.5) M a, (300 ± 9) M a, and (280 ± 12) M a, respectively, and the initial 87Sr / 86Sr ratios were determined in the southern area of the Mamu Obo fault in the study area 0.704 33, 0.704 35 and 0.703 84. The results show that the granites in the study area are formed in different stages of mid-late stage of Variscan. The Wutublak pluton was formed in the Early Carboniferous and is a calc-alkaline granite with late collision orogeny. It may be a product of partial melting of the Early Devonian Nb rich basalt. Combined with the predecessor plate subduction time (408 ~ 376 M a), it is speculated that the collision time limit between Siberian plate and Kazakhstan-Zunggar plate is 376-344 Ma. The Aleretopedi rock body formed in the post-collision tension environment may be the product of partial melting of the medium-basic volcanic rocks formed in the island arc environment. Although the Hudson rock body is also formed in the post-collision tension environment, A higher degree, belongs to the granite class related to magmatic underplating.