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1、100020569ö1999ö015(04)20623229ActaPetrologicaSinica岩石学报大别山北麓侏罗系大理岩砾石的碳-氧同位素组成及3地质意义111121李任伟江茂生李忠孙枢金福全张雯华11中国科学院地质与地球物理研究所,北京100029;21合肥工业大学资源与环境科学系,合肥230026.1.InstituteofGeologyandGeophysics,ChineseAcademyofSciences,Beijing100029;2.DepartmentofResourceandEnvironmentSciences,H
2、efeiIndustrialUniversity,Hefei230026.1999205231收稿,1999208230日改回.LiRenwei,JiangMaosheng,LiZhong,SunShu,JinFuquanandZhangWenhua.1999.Carbonandoxygenisotopiccom-positonsofthemarbleconglomeratesofJurassicageinthenorthernmarginofDabieMountains,China.ActaPetrologicaSinica,15(4):623～
3、629AbstractThestrataofSanjianpuandFenghuangtaiformationsofJurassicageinthenorthernmarginofDabieMountains13orthesouthpartofHefeiBasincontainmarbleconglomeratesthatbelongthesedimentsofalluvialfan.DCvaluesofthe18marbleconglomeratesrangefrom-117to113permil,majorityofthemisclosetoz
4、ero.DOvaluesofthemarbleconglom213eratesrangefrom615to2310permil.DCvaluesofthemarbleofFozilingGroupinDabieblockarefrom-210to-215per1813mil,theDOvaluesfrom613to1311permil.DCofthemarbleoccurredinhighpressureandultra2highpressuremetamor218phicrocksbeltsofDabieblockare1～6permil,the
5、DOfrom5to23permil.Themarkeddifferenceincarbonisotopecom2positionbetweenthemarbleconglomeratesandthemarblesindicatesthattherocksinDabieblockcannotbetheprovenance1318areafortheJurassicmarbleconglomerates.Inaddition,havingthecharacteristicsthatthecrossplotsofDCandDOshow1318little
6、variationofDCwithdecreasingDO,itcanbededucedthattheJurassicmarbleconglomeratesrecordstheprimaryde2positionalcarbonisotopiccompositionofthesourcerocks.KeywordsJurassic,Marbleconglomerates,Carbonandoxygenisotopes,Provenance,DabieMountains摘要在大别山北麓、合肥盆地南缘侏罗系三尖铺组和凤凰台组地层中含有大理岩砾石,属山麓
7、冲积扇环境沉积。它们131813的DC数值范围为-117‰～113‰,大多数近于零值,它们的DO数值从615‰～2310‰。大别地块佛子岭群大理岩的DC1813数值为-210‰～-215‰,DO数值范围从613‰～1311‰。大别地块高压和超高压变质岩带的大理岩的DC数值为1‰～186‰,DO数值为5‰～23‰。碳同位素组成的明显差别表明现今大别地块佛子岭群和高压、超高压变质岩不是合肥盆地南缘1318侏罗系大理岩砾石的来源区。由于DC的数值不随DO值的降低而变化,且分布在一个狭窄的范围,合肥盆地南缘侏罗系大理岩砾石的碳同位素组成代表了它的原岩在沉积
8、时海水的同位素记录。关键词侏罗系;大理岩砾石;碳和氧同位素;源区;大别山中图法分类号P58817;P597123本文属中国
