• 责任者：Duan Zhiming (Chengdu Institute of Geology and Mineral Resources ; China Geological Survey ; Chengdu 610082 ; China) ; Zhang Yuxiu
• 刊名：Acta Geologica Sinica
• 出版年：2013
• 卷期：87(12)
• 关键词：石英闪长岩 ; quartz diorite ; 岩石地球化学 ; lithogeochemistry ; 西藏 ; Tibet
• 页码：p.1874-1886
• 图表：11 illus., 3 tables, 74 refs.
• 分类号：0801
• issnNo：ISSN0001-5717
• isbnNo：CN11-1951/P

     The Mazicuo quartz diorites is located at southwest of the Xainshuihe fault, southern Songpan-Ganzi Terrane. The quartz diorites demonstrate high potassium （3.53%-3.86%）, Ca-rich （4.91%-6.07%）, low A1 content （14.60%-15.24%, A/CNK=0.80-0.89） and total rare earth elements （REE）. Light rare earth elements （LREEs） are enriched but slightly Eu depleted, with whole rock （8- Sr/86 Sr）i= 0. 707407 -0. 707640 implying that the Mazicuo magma origined from crust-mantle mixed melting or partial melting of lower crust. The Mazieuo quartz diorites belong to lower crust-remelting I-type high-potassium calc-alkaline granite series. The trace element diagrams for discriminating tectonic environments indicate that the Mazicuo quartz diorites resemble volcanic arc granites. The enrichment in Rb （60.1 × 10 6 -85.9 ×10-6） andCs （4.01×10-6-19. 62×10-6）, and high K20/Na20 （1. 31-1. 82） ratio suggest that biotite-rich sources are responsible for the Mazicuo magma. The zircon SHRIMP U-Pb age of 221-2.0 Ma （MSWD=I. 4） shows the intrusive age is Late Triassic, while the whole-rock Rb-Sr age of 207＋2.0 Ma may indicate the quartz diorites uplifted at late Late Triassic. The Mazicuo quartz diorites might form in Late Triassic back-arc tectonic background and derive from crust-mantle mix melting resulting from diapiric uplifting of lithospheric mantle magma.