Cenozoic Geological Evolution Of Tanggula Mountain In The Hinterland Of Qinghai-Tibetan Plateau And It Respond In Collision Effect Of India-Asia Plate

On the basis of the latest studies of continental kinetics and plate tectonics and combining the geological and geophysical materials with the accurate study of isotope chronology, this paper lays stress on Tanggula Mountain in the hinterland of Qinghai-Tibetan plateau. Following the geological events that represented by evidences, it reshapes the process of the geological evolution of the hinterland in the plateau. Through the studies about Late Mesozoic-Cenozoic crust -mantle magma movement, Cenozoic tectonic deformed and tectonic sediment response of Tanggula mountain, this paper precisely depicts the uplift process of Tanggula in the hinterland of the plateau and the climatic and environmental effects that caused by the uplift of the plateau.Based on the study of lithology on late Mesozoic-Cenozoic granite of Tanggula Mountain, it is indicted that there are three types of lithological combination, namely, the combination of monzonitic granite-moyite-feldspar granite porphyry of Longyala granitic mass, the combination of pyroxene quartz monzonite-quartz monzonite-monzonitic granite-quartz monzonitic porphyry of Munai granitic mass and the combination of monzonitic granite-monzonitic granitic porphyry of Saiduopugangri granitic mass. It is showed by the constants and the geochemical features of rare-earth elements that SiO₂ is in a relatively good positive correlation with K₂O with the increase of the content of SiO₂ in the granite of same stage, but SiO₂ is in a relatively good negative correlation with TiO₂ Al₂O₃,FeO, MgO, CaO and P₂O₅. All the samples contained relatively high content of Rb, Th, K, Ce and light rare-earth elements and formed similar partition modle of rare-earth elements that has negative anomaly Eu. The geochemical features of microelements show that these granites have properties of crust-mantle mixed source. The geochemical features of rare-earth element also support this further. The granites in the studied area have medium value of ⁸⁷Sr/⁸⁶Sr (0.7060-0.7106) and ¹⁴³Nd/ ¹⁴⁴Nd (0.512441). They are higher than the modern value of 0.70478 of modern uniform gather warehouse (⁸⁷Sr/⁸⁶Sr) _CHUR lower than the modern value of 0.51264 of spherolite aerolite uniform gather warehouse (¹⁴³Nd/¹⁴⁴Nd) chur respectively. The isotope geochemical of Sr and Nd reveal that these granites came from crust-mantle mixed formation. It is indicated by the accurate dating of U-Pb isotope chronology of single zircon in the typical masses of three rock combination that Longyala granite and Munai granite were formed in 69.8 ± 2.0- 67.1±2.0Ma, Saiduopugangri granite was formed in 40.6 ± 3.1Ma. The systemic apatite fission-track dating was carried on the Munai granitic mass of different elevations.