| The mechanisms of formation and petrogenesis of orogenic belt, one of the places with most active tectonic events on the Earth, are having been hot studied by geologist for a long time. As the granite in orogenic belt recorded every stage in process of orogenesis in material, it's very effective to reconstruct the deep dynamics and interaction of crust-mantle during orogenesis based on the study of characteristics of magma-origin and their mechanism. Concerning the East Kunlun orogenic belt in central-west China and inner Qinghai-Tibetan Plateau, granite intruded in overwhelming volume with multi-period and complicated litho-feature, especially for Hercynian-Indosinian. The dissertation managed to study systematically on field geology, lithofacies, petrologic geochemistry and LA-ICP-MS Zircon chronology, focused on petrogenesis, origin of petrologic material, formating tectonic setting and their geological significance. After that, together with regional geo-settings and the advanced study fruits of petrology, following cognitions are concluded:1. Helegang Xilikete granitoids are mainly of granodiorite, in which contents of oxides are SiO2=67.12wt%～73.88wt%, Na2O=1.2wt%～3.12wt% and K2O=3.04wt%～4.62wt%, while Na2O/K2O=0.67～1.8 and Mg# is about 53 for average. The rocks are enriched in LREE and depleted in HREE, and the ratios of (La/Yb)N, (Gd/Yb)N,and Yb/Lu of which are 8.72～35.3,1.36～1.80 and 5.68～7.24 respectively, together with 8Eu ranging between 0.86 and 0.95 and low contents of Y and Yb relatively. For trace elements, the rocks are enriched in LILE like Rb, Th, Ba, U, La et al., and are depleted in HFSE intensely, such as Nb, P, Ta, Ti et al.. Besides, the MME show apparent differences with their host rocks in lithologic geochemistry, such as being poor in Si and enriched in Mg, Fe, Ti, Ga relatively.2. Keke'EAlong rocks are quartz diorite in majority with some characteristics similar to adakite in lithologic geochemistry, which showing concrectely as follows:SiO2=60.08wt%～62.69wt%, Na20/K2O=1.41～1.83 and 1.57 for average, Mg#=47～52, enriched in LILE and LREE, apparent differentiation between LREE and HREE, (La/Yb)N=11.8～18.4, Sr>400×10-6, Sr/Y=38.8～26.7, Y/Yb=10.7～11.7, a little negative anomaly in Eu(δEu=0.83～0.88), relatively depleted in HREE and Y(12.5×10-6～15.6×10-6).3. Resorted to method of LA-ICP-MS Zircon U-Pb chronology, the intruded ages of Helegang Xilikete rocks and Keke'EAlong rocks are obtained for about 230.2±4.6Ma and 221±3.9Ma respectively, which indicate that the two rocks both are formatted in Mid-Late Triassic, and the crystallized age of the MME is 231.9±5.7Ma, syn-formated with host rocks-Helegang Xilikete granodiorite, showing that there were magma mixing process in the eastern section of the East Kunlun area during Indosinian.4. According to lithological geochemistry data, we believe that Helegang Xilikete granitic rocks were formatted by partial melting of lower-crust, which was resulted from diapir of athenospheric magma triggered by breaking up of subduction slab, and the MME of which might be formatted by mixing between mafic magma, the product of partial melting of lithosperic mantle, and some part of host rocks-granodiorite when they were arising. While Keke'EAlong rocks should be formatted by dehydration melting of detached lower-crust after they sank into beneath lithosperic mantle.5. In Middle and Late Triassic, paleo-Tethys tectonic region collided and lifted completely, in which lower-crust detachment occurred companying by bulk of magmatism, and tectono-thermo events started frequently. After that, the eastern part of the east Kunlun area went to the evolution stage of intra-orogenesis, which indicates the perish of paleo-Tethys ocean in the east section ultimately.
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