| 羌塘中部各拉丹冬二长花岗岩体同位素地质年代学和地球化学研究 |
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| 关键词:central Qiangtang Geladandong granite isotope geochronology geochemistry |
| 基金项目:国土资源部国土资源大调查项目(编号:200013000135) |
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| Isotope Geochronology and Geochemical Characteristics of Geladandong Monzonitic Granite in Centeral Qiangtang |
| The Geladandong intrusive body mainly consists of monzonitic granite, with the single zircon U_Pb age being 40±3 Ma, the Rb_Sr isochron age of the rock being 47±0.4 Ma, and the K_Ar ages of plagioclase, hornblende and biotite being 37.1 Ma, 45.8 Ma, 48 Ma, respectively. The rock body was formed in Eocene. The rocks have high content of alkali and potash (K_2O>Na_2O), belonging to high_potash calc_alkalic series. The trace elements are characterized by enrichment of LREE, LILE (Th, U) and depletion of HFSE. The 87 Sr/ 86 Sr ratios, the ε_ Nd (t)ratios and the δ 18 O values range from 0.70701 to 0.70724, -6.0 to -4.1, and 8.18‰ to 9.01‰, respectively. These data prove that the tectonic setting is volcanic island arc granite. The collision of the Indian plate with the Eurasian plate led to the large_scale uplift from 55 Ma. During the nearly SN_trending compression and shortening, Qinghai_Tibet plateau probably produced a tensile structure parallel to the main stress in Qiangtang terrane, leading to the emplacement of Geladandong granite. This is one of the hot tectonic events produced in northern Qiangtang terrane by the uplift of Qinghai_Tibet plateau. |
| BAI Yun-shan,LI Li,NIU Zhi-jun,YAO Zhou-fa,DUAN Qi-fa.2006.Isotope Geochronology and Geochemical Characteristics of Geladandong Monzonitic Granite in Centeral Qiangtang[J].Acta Geoscientica Sinica,27(3):217-225. |
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