摘要
合肥盆地的形成演化与大别造山带具有密切的耦合关系,充填了来自造山带剥蚀的碎屑物质,从而记录了大别造山带隆升和剥蚀历史的关键信息。为了给大别造山带后碰撞阶段隆升演化历史提供信息,选择合肥盆地中部下白垩统朱巷组和古近系定远组开展详细的碎屑锆石LA-ICP-MS U-Pb定年工作。朱巷组碎屑锆石年龄特征相对复杂,主要表现为具有新元古代中期和三叠纪2个主年龄峰以及一系列次级年龄峰;定远组则主要具有新元古代中期主年龄峰,兼有部分古元古代和太古代末年龄峰。结合现有资料综合分析可知,朱巷组物源区主要为大别造山带,其下部地层向上部地层碎屑锆石年龄特征的转变反映了大别造山带后碰撞阶段造山带北部高压—超高压岩石逐渐被剥蚀殆尽的过程;定远组物源区主要为合肥盆地东侧的张八岭隆起,物源物质可能来源于该隆起内分布的震旦系。晚白垩世末—古近纪初,合肥盆地沉积岩的主要物源区由大别造山带转变为张八岭隆起。这为更好地认识合肥盆地及其周边地区的构造演化提供了新的证据。
Rock materials in an orogen are usually large-scale denuded and transferred to their surrounding basins during the post-collisional stage.Therefore,studies on sedimentary rocks in these basins are helpful for better understanding the evolutionary history of the orogen.The Hefei Basin,located north of the Dabie Orogen,was filled with clastic materials from the orogen,recording key information on its uplift and denudation history.In this study,sandstones of the Lower Cretaceous Zhuxiang Formation and siltstones of the Paleogene Dingyuan Formation in the central Hefei Basin were selected for detailed detrital zircon LA-ICP-MS U-Pb dating.The detrital zircon age frequencies in the Zhuxiang Formation show Triassic and middle Neoproterozoic age clusters,whereas the Dingyuan Formation has a predominant middle Neoproterozoic age cluster,with secondary age clusters in the Paleoproterozoic and the Archean.All the samples lacked or contained few Early Cretaceous zircon ages.Combined with the results of previous studies,it can be concluded that the provenance of the Zhuxiang Formation is mainly the Dabie Orogen and that its formation age corresponds to the late stage of the Fenghuangtai Formation in the southern Hefei Basin.Different detrital zircon age frequencies in different samples correspond to the process in which the high-pressure and ultrahigh-pressure rocks were gradually denuded in the Dabie Orogen during the Early Cretaceous.In the Paleogene,the Hefei Basin was surrounded by a series of uplifts,which greatly reduced the diversity of clastic material sources of the Paleogene Dingyuan Formation.Because the detrital zircon age frequencies of the Dingyuan Formation are consistent with those of the Sinian strata in the South China Block,it can be inferred that the source materials of the Dingyuan Formation mainly come from the Sinian of the Zhangbaling Uplift.The provenance of sedimentary rocks in the Hefei Basin changed from the Dabie Orogen to the Zhangbaling Uplift at the end of the Late Cretaceous or the beginning
作者
杨隽豪
王勇生
白桥
马威威
YANG Juanhao;WANG Yongsheng;BAI Qiao;MA Weiwei(School of Resources and Environmental Engineering,Hefei University of Technology,Hefei 230009,China)
出处
《地球科学进展》
CAS
CSCD
北大核心
2022年第8期871-880,共10页
Advances in Earth Science
基金
国家自然科学基金面上项目“大别造山带北淮阳单元的变形历史与构造属性”(编号:41572186)资助
关键词
合肥盆地
中—新生界地层
碎屑锆石定年
物源分析
Hefei Basin
Mesozoic-Cenozoic strata
Detrital zircon dating
Provenance analysis
