Abstract–Anorthosites of the Olonkhuduk pluton of the Central Asian Orogenic Belt are dated at 1772 ± 1 Ma (ID TIMS U-Pb zircon method). Similar age estimate (1784 ± 10 Ma) was previously obtained for anorthosite of the Khungilingol pluton from the Ider block of the Tarbagatai terrane. These data indicate a significant time gap (70–60 Ma) between the collision that formed the Early Precambrian blocks of the Baidaric and Tarbagatai terranes in the range 1860–1850 Ma and the emplacement of the anorthosites. The termination of accretion-collision processes and consolidation of the Early Precambrian block of the Baidaric terrain are marked by the postkinematic subalkaline granites with an age of 1825 ± 5 Ma. Geochemically, the anorthosites of the Olonkhuduk and Khungilingol plutons are similar to the typical anorthosites of ancient cratons. Sm-Nd isotopic data indicate a mixed source of these anorthosites: juvenile mantle component of Paleoproterozoic age and crustal component of Neoarchean age. It can be assumed that the primary mafic magma of the anorthosites experienced a significant crustal contamination. Based on the similar geologic setting, age, and composition, the anorthosites of the Olonkhuduk and Khungilingol plutons can be ascribed to a single within-plate complex. The age values obtained for the anorthosites coincide with the estimated age of rift magmatism in the North China craton at 1.8–1.75 Ga and the emplacement time of mafic dikes swarms at 1778 ± 3 Ma (SIMS U-Pb method). Thus, the considered Early Precambrian blocks by the end of the Paleoproterozoic (about 1900–1850 Ma) could be a part of the Columbia supercontinent (Rogers and Santosh, 2002).

中文翻译：

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中亚造山带百达岭地带的Olonkhuduk斜长岩斜体：地质位置和年龄

摘要–中亚造山带的Olonkhuduk岩体的钙铁矿的年代为1772±1 Ma（ID TIMS U-Pb锆石法）。以前从塔尔巴加泰（Tarbagatai）地块的Ider块获得的Khungilingol岩体的钙硅钙石的钙钛矿的早熟年龄估计相似（1784±10 Ma）。这些数据表明，在1860-1850 Ma范围内形成Baidaric和Tarbagatai地层的前寒武纪块体的碰撞与钙硅钙石的位置之间存在明显的时间间隔（70-60 Ma）。增生碰撞过程的终止和贝加达克地区前寒武纪早期块体的固结特征是运动后亚碱性花岗岩，年龄为1825±5 Ma。在地球化学上，Olonkhuduk和Khungilingol岩体的钙硅石与古代克拉通的典型钙硅石相似。Sm-Nd同位素数据表明这些钙长石的混合来源：古元古代时代的地幔组分和新古代时代的地壳组分。可以假定，钙铁矿的原基性镁铁质岩浆经历了明显的地壳污染。基于相似的地质背景，年龄和组成，Olonkhuduk和Khungilingol岩体的原位生物可归因于单个板内复合物。获得的钙长岩的年龄值与华北克拉通裂谷岩浆作用的估计年龄在1.8–1.75 Ga以及铁磁石堤群的安置时间在1778±3 Ma（SIMS U-Pb方法）相吻合。因此，到古元古代末（大约1900-1850 Ma）之前被认为是早寒武世块体可能是哥伦比亚超大陆的一部分（Rogers和Santosh，2002）。