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J4 ›› 2015, Vol. 21 ›› Issue (2): 186-.DOI: 10.16108/j.issn1006-7493.2

• 岩石 矿物 矿床学 • 上一篇    下一篇

瓮安埃迪卡拉系灯影组叠层石磷块岩形成环境及成矿机制

张 伟,杨瑞东*,毛 铁,任海利,高军波,陈吉艳   

  • 出版日期:2015-06-20 发布日期:2015-07-10

SedimentaryEnvironmentandMineralizationMechanismofthe StromatoliticPhosphoriteintheEdiacaranDengyingFormation, Weng′anCountyofGuizhouProvince,China

ZHANG Wei, YANG Ruidong*, MAO Tie, REN Haili, GAO Junbo, CHEN Jiyan   

  • Online:2015-06-20 Published:2015-07-10

摘要:

瓮安地区埃迪卡拉系灯影组叠层石磷块岩是瓮安—福泉磷矿区新发现的含磷层位。磷块岩以典型的叠层石构造为主 要特征,呈透镜状生物礁(藻礁)形式产于灯影组顶部。叠层石磷块岩的矿物组成主要为磷酸盐矿物及碳酸盐矿物;白色 纹层富含磷酸盐矿物,而暗色纹层磷酸盐矿物含量较低,主要为碳酸盐矿物。通过对叠层石磷块岩矿物学及地球化学特征 进行研究,提出灯影组叠层石磷块岩属于潮下带半局限环境叠层石礁,是大量藻类通过生物或生物化学作用,将海水中磷 质富集-沉淀而形成磷质柱状叠层石礁;磷酸盐的矿化主要发生在沉积物—海水界面弱碱性次氧化环境,藻类在磷块岩形成 过程中起重要作用。

关键词: 灯影组;叠层石磷块岩;地球化学;成矿环境

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