The main rock type of Maxingdaban granitic pluton from Qimantag of Qinghai in the eastern Kunlun is monzogranite. It consists of plagioclase (30% similar to 35%) + K-feldspar (25% similar to 33%) + quartz (23% similar to 25%) + biotite (3% similar to 5%). Whole-rock wanalysis shows SiO2 68. 61% similar to 69. 37%, K2O 3. 95% similar to 4. 08%, P2O5 0. 11% similar to 0. 12%, FeOT/MgO 4. 02 similar to 4. 21, A/CNK (0. 96 similar to 0. 99) <1, which must be high-K calc-alkaline series metaluminous granite. It represents the features of I-type granite. According to REE partition diagram and spider diagram, the granite shows a marked chemical resemblance to continental arc granite, exhibiting enrichment in LILEs such as Rb and Th, but depletion in HFSEs such as Sr, P, Ti, Nb and Ta. Nd-143/Nd-144 (0. 512326 similar to 0. 512340) and epsilon(Nd)(t) (-2. 5 similar to -3.2) imply the monzogranite shares the characters of crust-mantle mixed I-type granite. Based on LA-MC-ICP-MS zircon U-Pb dating, the emplacement of Maxingdaban monzogranitic pluton occurred at 218 +/- 2Ma. Zircon Hf-176/Hf-177 ratio is low (0. 282517 similar to 0. 282623), epsilon(Hf)(t) is -4. 43 similar to -0. 62, which may indicate a mixture with mantle source (large positive epsilon(Hf)(t)) and ancient crust (large negative epsilon(Hf)(t)). The accordance of t(DM2) (1. 20 similar to 1. 25Ga) of Nd and t(DM2) (1. 08 similar to 1. 28Ga) of Hf leads to the conclusion that the crust-mantle differentiation occurred at Mesoproterozoic in Qimantag and indicates the source of the granite may be partly from the pre-Mesoproterozoic materials. It is suggested that the Maxingdaban monzogranitic pluton emplaced at the same time with the Qimantag Late Triassic volcanic rock, when the Paleo-Tethys Ocean closed.
