• 责任者：Liu Dong (State Key Laboratory of Geological Processes and Mineral Resources ; School of Earth Sciences and Mineral Resources ; China University of Geosciences ; Beijing 100083 ; China) ; Zhao Zhidan
• 刊名：Acta Petrologica Sinica
• 出版年：2013
• 卷期：29(11)
• 关键词：碱性岩 ; alkali rocks ; 铀—铅计时 ; U-Pb dating ; 青藏高原 ; Qinghai-Tibetan Plateau
• 页码：p.3703-3715
• 图表：5 illus., 4 tables, 40 refs.
• 分类号：0801
• issnNo：ISSN1000-0569
• isbnNo：CN11-1922/P

     Zircons entrained in mantle-derived magmas offer a prime opportunity to reveal cryptic magmatic episodes in the deep crust. We have investigated zircons from mantle-derived uhrapotassic veins in the Xuena area, southern Lhasa subterrane. Zircons in the Xuena uhrapotassic rocks reveal four major magmatic pulses around 〈 100Ma, 300 - 400Ma, 450 - 500Ma, and 700 - 850Ma. The high U/Yb ratios and low Y contents of these zircons demonstrate their continental origin. Cenozoic-Mesozoic and Late Paleozoic magmatism have been widely identified from the southern Lhasa subterrane, suggesting the contribution from overlying juvenile crust. But similar Proterozoic-Early Paleozoic age distributions （450 -500Ma and 700 -850Ma） between these zircon xenocrysts and those dating records in the Himalayan orogenic belt corroborate the input from underthrusted Indian continental crust. Furthermore, the increasing （Dy/Yb） N ratio since - 60Ma and rapid decreasing zircon εHf （t） values, from ＋ 10 - ＋ 5 to - 10 - - 25, are interpreted to reflect significant and progressive crustal thickening in response to India-Asia convergence and the contribution from subducted Indian continental crust to postcollisional magmatism in the southern Lhasa sub-terrane.