Geochemical Criteria of the Upper Sinian Cherts of Hydrothermal Origin on the Southest Continental Margin of the Yangtze Plate

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摘要 TheUpperSinianbeddedchertsarewidelydistributedonthesoutheastcontinentalmarginoftheYangtzeplate,withatotalthicknessrangingfrom20to150m,Thechertsareverysimpleinchemicalcomposition,withthecontentsofsiliceousmineralsexceeding90%andthoseofothermineralspeciesbeingverylow.Thetotalcontentoftraceelementsisconsiderablyvarialbe,Thecontentsofmosttraceelementsarelowascomparedwiththeircrustclarkevalues.ButthesechertsareveryrichinthetraceelementsBa,As,Ab,AgandU,coupledwithrelativelyhighcontentsofFe,MnandlowcontentsofAl,Ti,andMg,ItcanbeidentifiedasthechertsofhydrothermaloriginintermsofthevaluesofFe/Ti,(Fe+Mn)/Ti,Al/(Al+Fe+Mn)andU/Th,IntheAl-Fe-Mn,andFe-Mn-(Cu+Ni+Co)×10diagramsandlg[U]-lg[Th],Cr-Zrdiagrams.allthesamplesfromtheareastudiedfallwithinthehydrothermalsedimentfield.Allthesecharacteristicsshowthatthechertsaremainlytheproductofhydrothermalprocesses.Thefactthattheδ30Sivaluesofthechertrangefrom0.0‰to0.7‰withδ18Ofrom20.1‰to23.6‰cleralymanifeststhatthesubmarinehydrothermalwateristhemainsourceofsilica.
机构地区 不详
出版日期 2000年03月13日(中国期刊网平台首次上网日期,不代表论文的发表时间)