Element geochemical characteristics of Mesozoic mudstones in the northern piedmont zone of the Kuqa depression and their implications to sedimentary environments

Bymeansofelementgeochemistry,thecharacteristicsofmajorelements,traceelementsand rareearthelements(REE)forTriassicandJurassicmudstonesfromthenorthernpiedmontzoneinthe Kuqadepressionwerestudiedanddiscussedfortheimplicationsfosedimentryenvironment.TheMesozoicmudstonesfromthenorthernpiedmontzoneintheKuqadepressionaredominentlyterrestrialfreshwatersedimentaryenvironments.REE arecharacterizedbyenrichmentoflightREE,andreflect the
sedimentarycharacteristicsofrapidaccumulationoforganicmatterandslowrechargeofterrigenousfine debris.FromtheTriassictotheJurassic,thepaleosalinityincreasedslightlywhilethepaleoclimatewas mainlyhumid,andthewholewasunderdysoxic-anoxicconditions.Thewarmandhumidpaleoclimate andlowerpaleosalinityduringthedepositionoftheHuangshanjieFormationareconducivetotheproductionoforganicmatterproductivity,andthedysoxic-anoxicconditionprovidespreservationconditions.Thehot-drypaleoclimateenvironmentbegantoappearintheperiodoftheQiakemakeFormation, andthehigherpaleosalinitymaypromotetheformationoforganicmatter,buttheanoxicconditionis moreconducivetoitspreservation.