Geochronology of Gneissic Plagioclase-Amphibolite from Beidahe Group-Complex in Western Segment of Qilian Mountains, China

• 责任者：He Shiping (Xi’an Institute of Geology and Mineral Resources ; China Geological Survey ; Xi’an 710054 ; China) ; Li Rongshe
• 刊名：Geological Bulletin of China
• 出版年：2010
• 卷期：29(9)
• 关键词：角闪岩 ; amphibolites ; 片麻状构造 ; gneissic structure ; 祁连山 ; Qilian Mountains
• 页码：p.1275-1280
• 图表：3 illus., 1 table, 12 refs.
• 分类号：0802
• issnNo：ISSN1671-2552
• isbnNo：CN11-4648/P

SHRIMP U-Pb dating of detrital zircons from Beidahe Group-complex, one of the oldest metamorphic series in the western segment of Qilian orogenic belt, shows the deposition occurred from 1 400 Ma to 863 Ma rather than Paleoproterozoic previously studied. High resolution LA-ICP-MS in situ dating yields the age of (724.4±3.7) Ma from gneissic amphibolite in Beidahe Group-complex located in Dang River, Subei County, Gansu Province, which indicates the protolith age of gabbro.The age equals to the geological record of Rodinia supercontinent break-down event. The study is of great significance to the existence of Rodinia supercontinent break-down event in the Qilian orogenic belt, and has further restricted the formation age of Beidahe Group-complex between 1 400 and 724 Ma.