Detrital Zircon U-Pb Geochronology of Dacaotan Group in the Conjunction Area of North Qinling and Qilian

• 责任者：Chen Yibing (State Key Laboratory of Continent Dynamics ; Department of Geology ; Northwest University ; Xi’an 710069 ; China) ; Zhang Guowei
• 刊名：Acta Geologica Sinica
• 出版年：2010
• 卷期：84(7)
• 关键词：碎屑岩 ; clastic rocks ; 铀—铅计时 ; U-Pb dating ; 秦岭 ; Qinling Mountains ; 祁连山 ; Qilian Mountains
• 页码：p.947-962
• 图表：3 illus., 3 tables, 32 refs.
• 分类号：0803
• issnNo：ISSN0001-5717
• isbnNo：CN11-1951/P

Detrital zircons LA-ICP-MS U-Pb dating was performed systematically on the Late Devonian Dacaotan Group in the conjunction area of North Qinling and Qilian. Three formations of Dacaotan Group are characterized from lower to upper by the followings: 1) with decreasing stratigraphic age, the proportion of pre -550 Ma grains in the three units decreases from 36% to 32%, and then to 25%; 2) the systematic increase in the proportion of the 750～2 600 Ma zicons from 54% to 65%, and then to 72% upward with stratigraphy height, is accompanied by an increase in the peak age of Proterozoic zircons on the age histograms.  The data confirm that the basement of North Qinling-Qilian microcontinent was the predominant source area for the sediments, the active magmatic arc and recycled collision orogen should be another important source area, and some detritus was derived further from the western block of the North China Craton.