Provenance and Tectonic Setting of the Neoproterozoic Diamictites from Jiayuan Formation in Northern Anhui Province:Evidence from Geochemical Study
SUN Lin-hua1),GUI He-rong1),CHEN Song1),MA Yan-ping1),WANG Gui-liang2) 1) School of Earth Sciences and Engineering,Suzhou University,Suzhou,Anhui 234000;2) School of Resource and Earth Sciences,China University of Mining and Technology,Xuzhou,Jiangsu 221008
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.
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