【摘要】 在野外调查和岩石学研究的基础上,对皖北新元古代贾园组混积岩进行了系统的元素地球化学(包括稀土元素)分析,结果表明:该套混积岩主要由不同比例(1:1.5～1:9)的碳酸盐和陆源碎屑组分混合而成,属于"相缘渐变沉积混合"。其元素含量与碳酸盐组分和陆源碎屑组分比例密切相关,但La、Th、Zr及Sc等元素之间的比值主要受控于陆源碎屑而相对稳定,可以用于识别碎屑物源区及其构造背景。地球化学特征证实混积岩中陆源碎屑组分主要来自与大陆岛弧有关的长英质火山岩,但也存在少量古老基底的参与。结合最近研究进展推断,皖北新元古代沉积活动可能主要发生在与1.0～0.8 Ga之间,其沉积环境与Rodinia超大陆汇聚过程中导致的华北板块东南缘弧后伸展有关。更多还原

【Abstract】 Field observation and petrographic study as well as a systematic analysis of major and trace elements(including rare earth elements) were carried out for diamictites from the Neoproterozoic Jiayuan Formation in northern Anhui Province.The results imply that these diamictites are composed of carbonates and terrigenous de-tritus of variable proportions(1/1.5～1/9) and belong to "mixed sedimentation with gradual facies change".The concentrations of elements are closely related to the relative concentrations of carbonates and terrigenous detritus,whereas the ratios between La,Th,Zr and Sc are controlled by terrigenous detritus with limited variations,and hence can be used as tracers for the discrimination of provenance of terrigenous detritus and its tectonic back-ground.Geochemical features demonstrate that the terrigenous detritus was mainly derived from the continental arc felsic volcanics,with minor contribution from the old basement.Combined with recent research achievements,the authors hold that the Neoproterozoic sedimentation in northern Anhui Province probably took place between 1.0 and 0.8 Ga,and the sedimentary environment was related to the back arc extension of the southeastern margin of the North China Craton during the convergence of Rodinia supercontinent.更多还原