地质学报2017，Vol.91Issue(7)：1522-1541,20.
鄂尔多斯盆地北部中生代中晚期地层碎屑锆石U-Pb定年与物源示踪
Detrital Zircon U-Pb Dating of Middle-Late Mesozoic Strata in the Northern Ordos Basin: Implications for Tracing Sediment Sources
摘要
Abstract
The distribution of U-Pb ages and their variation features have been comprehensively studied using LA-ICP-MS in-situ isotopic dating of the detrital zircons from sandstones of Zhiluo Formation of the Middle Jurassic and Zhidan Group of the Early Cretaceous from the Hangjinqi area,Ordos basin.Based on the statistic and comparison of isotopic dating results for the plutons in and around this area by previous researchers,along with regional structural background,the provenance of Zhiluo Formation and Zhidan Group and their evolution was also addressed systematically.The main conclusions can be drawn as follows.(1) Zircons from four samples of Zhiluo Formation and two samples of Zhidan Group yielded four peak ages of 270～280 Ma,320～340 Ma,1800～2000 Ma,2300～2500 Ma,with minor zircons from the Zhidan Group having age range from 230 Ma to 240 Ma only appear.(2) The sandstones in the Hangjinqi area mainly sourced from the gneisses,granulites,khondalite and the Hercynian intermediate-felsic intrusive rocks in Yinshan and Daqingshan-Wulashan,with minor from Langshan and the khondalite from the Jining area.(3) The two ages of 1800～2000 Ma and 2300～2500 Ma may reflect the tectonic thermal event at the basement of the North China Craton.The two age of 270～280 Ma and 320～340 Ma may record two fast subduction events of the Paleo-Asian Ocean which occurred during Early Carboniferous to Middle Permian.(4) The 230～240 Ma zircon which appeared in the Zhidan Group indicates that the Indosinian intrusive rock was uplifted to the surface by intensive crustal overthrusting caused by the Yanshan movement in Late Jurassic in the northern margin of Ordos Basin,and denudation further increased provenance from the Indosinian intrusive rock for the study area.(5) Comparison with the samples from the mid-Jurassic Zhiluo Formation shows that peak points of the samples from the lower Cretaceous Zhidan Group at 2300～ 2500 Ma significantly increase.This probably resulted from relative expansion of the sedimentary boundary in the northern margin of the basin in the Early Cretaceous,thus increasing provenance proportion from the Yinshan Terran.关键词
中侏罗统直罗组/下白垩统志丹群/碎屑锆石U-Pb定年/物源示踪/鄂尔多斯盆地北部Key words
Zhiluo Formation of Middle Jurassic/Zhidan Group of Lower Cretaceous/detrital zircon U-Pb dating/provenance analysis/northern Ordos basin引用本文复制引用
雷开宇,刘池洋,张龙,吴柏林,王建强,寸小妮,孙莉..鄂尔多斯盆地北部中生代中晚期地层碎屑锆石U-Pb定年与物源示踪[J].地质学报,2017,91(7):1522-1541,20.基金项目
本文为国家自然科学重点基金项目(编号41330315)、西北大学大陆动力学国家重点实验室科技部专项经费、中国地质调查局工作项目(编号12120114009201)联合资助成果. （编号41330315）
