摘要:
应用元素地球化学方法,对库车坳陷北部山前带中生界三叠系和侏罗系泥岩的主量元 素、微量元素和稀土元素(REE)特征进行了研究,并探讨了其沉积环境意义。 结果表明:库车坳 陷北部山前带中生界泥岩主要为陆相淡水沉积,稀土元素具有轻稀土富集特征,稀土元素总量反 映有机质快速堆积、陆源细碎屑补给速度慢的沉积特征。 从三叠纪到侏罗纪古盐度略有上升,古 气候以温暖湿润为主,整体处于贫氧—缺氧环境。 黄山街组沉积时期温暖湿润的气候与较低的 古盐度有利于有机质的形成,贫氧—缺氧环境提供保存条件。 至恰克马克组沉积时期古气候开 始向干燥炎热转化, 且古盐度较高,影响有机质产量,但缺氧环境更有利于其保存。
Abstract:
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.
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