地质学报2017，Vol.91Issue(11)：2521-2544,24.
鄂尔多斯盆地西南部上三叠统延长组碎屑锆石U-Pb定年及其物源意义
Detrital Zircon U-Pb Dating of the Upper Triassic Yanchang Formation in Southwestern Ordos Basin and Its Provenance Significance
摘要
Abstract
Due to the special tectonic location and the limit of exploration work,it has been controversial about the provenance of the Chang 6 of Upper Triassic Yanchang Formation in the southwestern Ordos Basin.Four samples of clastic rocks were collected from wells Li78,Zhuang33,Yan40 and the strata of Chang 6 in the Ruishuihe area in southwestern Ordos Basin to conduct the LA-ICP-MS zircon U-Pb isotope geochronologic dating.The results show that all samples have five similar age groups:250～350 Ma,400 ～660 Ma,920～1200 Ma,1750～1950 Ma and 2200～2600 Ma.Corresponding to it,the peak age of every group concentrates on 284～330Ma,430～460 Ma,950～1000 Ma,1850～1915 Ma and 2250～2450 Ma respectively.This study carried out a comprehensive analysis of provenance position,parent rock time,and lithology of Chang 6 section through comparison with age distribution of detrital zircons from adjacent areas and heavy minerals data.The results indicate that the provenance of the study area has characteristics of multi-orientation,multi-period and multi-type.The main sources of Chang 6 Formation are the igneous rocks and metamorphic rocks of Caledonian and Jinningian periods from the western part of North Qinling Mountain,the eastern part of North Qilian Mountain and West Qinling in the southwestern Ordos Basin as well as Paleoproterozoic khondalite series from the northeastern Ordos Basin.Besides,Variscan magmatic rocks from Alxa Block in the northwestern basin and metamorphic basement rocks from the southeastern part of Ordos Block also made partial contribution.This result is helpful for restoring sedimentary environment of prototype basin and guiding next step work of oil exploration.关键词
碎屑锆石U-Pb定年/重矿物/物源分析/长6段/鄂尔多斯盆地西南部Key words
U-Pb dating of detrital zircon/heavy mineral/provenance analyse/the Chang 6 of Upper Triassic Yanchang Formation/southwestern Ordos Basin引用本文复制引用
孙迪,冯乔,刘震,卢朝进,夏鲁..鄂尔多斯盆地西南部上三叠统延长组碎屑锆石U-Pb定年及其物源意义[J].地质学报,2017,91(11):2521-2544,24.基金项目
本文为海外及港澳学者合作研究基金(编号41428201)资助的成果. （编号41428201）
