俄罗斯远东地区晚中生代花岗岩类的时空分布及其地质意义

    Spatial and temporal variations of Late Mesozoic granitoids in Russian Far East area and their significance for geological setting

    • 摘要: 在俄罗斯远东地区晚中生代花岗岩类年龄和相关地球化学数据的基础上,初步建立了该区晚中生代花岗岩类的年代学格架:大致以145Ma为界,分为侏罗纪(178~151Ma)和早白垩世(142~122Ma)2期。侏罗纪的花岗岩类主要为花岗岩-花岗闪长岩-石英二长岩组合,总体上为准铝质—强过铝质高钾钙碱性系列;早白垩世的花岗岩类主要为花岗岩-石英闪长岩-石英二长岩组合,主要为过铝质钙碱性—高钾钙碱性系列—钾玄岩系列。2期花岗岩稀土元素配分曲线均呈右倾型,重稀土元素曲线较平坦,都富集大离子亲石元素(如U、K)和轻稀土元素。与中国东北地区晚中生代花岗岩类对比,中国东北地区总体以兴安岭为中心,中间为早白垩世的花岗岩类,两侧为侏罗纪花岗岩类对称分布。境内外的侏罗纪花岗岩类构造背景不同,其分布与鄂霍次克洋和太平洋板块的俯冲有关,早白垩世花岗岩类可能形成于鄂霍次克带挤压造山后的伸展垮塌和太平洋板块的俯冲弧后伸展阶段。

       

      Abstract: Based on systematic collection of ages and geochemical data, this paper has preliminarily established geochronological framework of the Late Mesozoic granitoids in Russian Far East area. These granitoids can be mainly divided into two periods, i.e., Jurassic period (178~151 Ma) and Early Cretaceous period (142~122 Ma). The Jurassic granitoids consist mainly of granites, granodiorites and quartz monzonite, and show metaluminous-peraluminous high-K, calc-alkaline granites characteristics. The Early Cretaceous granitoids consist mainly of granite, quartz diorite and quartz monzonite, and are characterized by peraluminous calc-alkaline, high-K-calc-alkaline and shoshonite granites. REE patterns of two periods of granitoids are all of right-inclined type, their HREE assume relatively flat curves and are enriched with large ion lithopile elements (such as U and K) and LREE. Compared with the Late Mesozoic granitoids in northeastern China, the Jurassic granitoids in Far East area show different tectonic settings, which is related to the subduction of the Okhotsk plate and the Pacific plate. The Early Cretaceous granitoids were formed in an extensional collapse period after the compressive orogeny of the Okhotsk belt or back-arc extension after the subduction of the Pacific plate.

       

    /

    返回文章
    返回