摘要
南盘江盆地中三叠世巨厚的复理石建造吸引了诸多地质学者,但对盆地内碎屑岩的物质来源问题仍存在分歧。为弄清盆地内碎屑岩系物源问题,此次选取南盘江盆地北部尾若地区中三叠统许满组2段浊积岩为研究对象,利用碎屑锆石LA-ICP-MS U-Pb测年,探讨其主要物源方向。测试结果显示,碎屑锆石U-Pb年龄存在239~340Ma、340~570 Ma、710~990 Ma、990~2300 Ma和2300~2600 Ma等5个年龄阶段,说明南盘江盆地中三叠统许满组碎屑物源复杂。利用碎屑锆石年龄与南盘江盆地周边可能性源区的锆石年龄组成对比,并结合区域性岩相古地理研究及区域构造演化史,认为南盘江盆地内巨厚浊积岩系物源主要来自盆地西南部的Song Ma缝合带、哀牢山剪切带及盆地东南部包括钦防褶皱带在内的云开地块。
Many geologists are interested in the massive thick turbidites of Middle Triassic flysch formation in the Nanpanjiang basin.However,the understanding on provenance of clastic rocks in this flysch formation of the basin remains contentious.In order to trace the source of clastic rocks of the Nanpanjiang basin,we have chosen turbidites of the second Member of Middle Triassic Xuman Formation in the Weiruo area of the northern Nanpanjiang Basin as research object to explore the provenance of sediments of the turbidite by utilizing LA-ICP-MS dating of detrital zircons.The testing results show that there are five ranges of detrital zircon U-Pb ages,including 239~340 Ma,340~570 Ma,710~990 Ma,990~2300 Ma,and 2300~2800 Ma,suggesting the complicated provenance of detritus sediments of the second Member of Triassic Xuman Formation in the northern Nanpanjiang basin.Based on the comparison of these detrital zircon U-Pb ages in this study area and other U-Pb ages of zircons of possible provenances in surrounding areas of the Napanjiang basin and the combination of regional lithofacies paleogeography and regional tectonic evolution history,it is believed that the source of massive thick turbidites in the northern Nanpanjiang basin could be mainly sourced from the Song Ma suture zone and the Ailaoshan shear zone in the southwest,as well as the Yunkai ancient land containing the Qin-Fang orogenic belt in the southeast.
作者
刘晓震
胡煜昭
郑爽
王占峰
LIU Xiao-zhen;HU Yu-zhao;ZHENG Shuang;WANG Zhan-feng(Kunming University of Science and Technology;Yunnan Mineral Resources Laboratory)
出处
《矿物学报》
CAS
CSCD
北大核心
2021年第1期69-77,共9页
Acta Mineralogica Sinica
基金
国家自然科学基金项目(编号:41672073)。
