Abstract:

 Stromatolitic phosphorite in the Ediacaran Dengying Formation was initially discovered in Weng′an-Fuquan area of SouthwesternGuizhouProvince,Chinawherephosphateoresarewidelydistributed.Asanewphosphorousstratumofphosphorite,itis characterizeddominantlybytypicalstromatoliticstructures.ThephosphoriteofstromatoliteislocatedatthetopoftheEdiacaran DengyingFormationthatiscomposedoflenticularorganicreef(algalreefofstromatolite).Themajormineralcomponentsofthe stromatoliticphosphoritearephosphatesandcarbonates.Thewhitelaminatedbedsareenrichedinphosphatemineralswhilethedark laminatedbedshavelowercontentsofphosphatemineralsandcontainmainlycarbonateminerals.Analysisofthemineralogicaland geochemicalcharacteristicsindicatesthatstromatoliticphosphoriteintheEdiacaranDengyingFormationisalgalreefofstromatolite thatwasformedinasemi-restrictedsubtidalenvironment.Accordingly,itcouldbeinferredthatthephosphoriccolumnarstromatolitic reefswereformedbyenrichmentinandprecipitationofphosphorusfromtheseawaterwithrichphosphorusduetocomplexbiological orbio-chemicalactionsofalgae.Inaddition,theresultsshowthatthemineralizationofphosphaticmineralsoccurredmainlyatthe sediment-waterinterfaceinweaklyalkalineandsuboxicenvironmentwherealgaehadplayedasignificantrole.

Key words: DengyingFormation;stromatoliticphosphorite;geochemicalcharacteristics;mineralizationenvironment