U-Pb dating of detrital zircons and geochemical characteristics of Inkisi Formation in the northeastern Angola area
Objectives:The sedimentary age,material source,sedimentary environment and tectonic setting of the arkose of Inkisi Formation in northeast Angola are discussed through detritonal zircon dating and petrogeochemistry,which provide scientific basis for the study of the evolution of Congo Basin.Methods:We performed the zircon LA-ICP-MS U-Pb isotopic dating,major elements and trace elements compositions of the arkose from Inkisi Formation in northeastern of Angola.Results:The results show that the 206Pb/238U age of detrital zircon is mainly concentrated in three peak age ranges of 2350～1900 Ma,1150～850 Ma,and 850～500 Ma,with the youngest zircon having a peak age of 531±9 Ma.Conclusions;The upper limit of depositional age of Inkisi Formation in this area is the Early Cambrian.The geochemical characteristics of the sandstone of Inkisi Formation show that the provenance has the characteristics of near-source transport of felsic provenance,and the water in the sedimentary period was an open freshwater environment of continental facies.Based on the age spectrum of detrital zircon,source identification of major trace elements and structure identification diagram,the results show that the West Congo tectonic zone is the main provenance zone,followed by the Lufilian tectonic zone and Angola shield.The tectonic environment of its provenance area is mainly active continental margin and passive continental margin tectonic environment background.
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