• 责任者：He Zhengjun (Institute of Geology ; Chinese Academy of Geological Sciences ; Beijing 100037 ; China) ; Niu Baogui
• 刊名：Geological Bulletin of China
• 出版年：2011
• 卷期：30(5)
• 关键词：风化壳 ; weathering crust ; 碎屑岩 ; clastic rocks ; 铀—铅计时 ; U-Pb dating ; 元古宙 ; Proterozoic ; 北京 ; Beijing
• 页码：p.798-802
• 图表：3 illus., 2 tables, 16 refs.
• 分类号：1300
• 出版序号：1142
• issnNo：ISSN1671-2552
• isbnNo：CN11-4648/P

///Recently, the Proterozoic rapakivi granites (dike) with the paleo-weathered mantle-clastic rocks covered directly by the sandstones of the Changzhougou Formation of Changchengian System are discovered in the Miyun County, Beijing. The detrital components of the rocks embrace the in-situ weathered mantle saprolites and coarse-grained clastic rocks from rapakivi granites. Through SHRIMP and LA-ICP-MS dating methods, the authors obtained the U-Pb dating ages of (1 682±20) Ma and (1 708±6) Ma from the detrital zircons sampled in the rocks; those age data are the same with the nearby Miyun rapakivi granite. The existence of this suite of weathered saprolites and clastic rocks, as well as the analysis of the dating results, have shown that the age of the base of the Changzhougou Formation should be younger than 1 682 Ma.