• 责任者：Wang Hongliang (Xi’an Center of Geological Survey ; CGS ; Xi’an 710054 ; China) ; Xu Xueyi
• 刊名：Acta Geologica Sinica
• 出版年：2011
• 卷期：85(8)
• 关键词：磁铁矿 ; magnetite ; 石英岩 ; quartzite ; 铀—铅计时 ; U-Pb dating ; 秦岭 ; Qinling Mountains
• 页码：p.1284-1290
• 图表：3 illus., 1 table, 22 refs.
• 分类号：0802
• issnNo：ISSN0001-5717
• isbnNo：CN11-1951/P

The study picked lots of zircons from magnetite quartzite at Xiaogoushan mining area.CL images of zircons show a distinct mantle-edge structure which most zircons have, oscillatory zoning developed within mantle indicating magmatic in origin, and late-stage metamorphic, grayish zoning edge. According to CL imaging features and genetic analysis of zircons, the authors obtained an upper intercept age of  (2 645±25) Ma  (MSWD=1.2) and a weighted mean ²⁰⁷Pb/²⁰⁶Pb age of  (2 645±24) Ma for the magnetite-quartzite magmatic zircons in Xiaogoushan mine area using microdomain U-Pb isotope LA-ICP-MS (laser ablation ICP-MS) determination. Two ages are consistent to each other, representing the formation age of protolith of quartzite. Based on above, the authors say that the age reflects an important regional metamorphism event in Archean.