青海省天峻南山蛇绿岩套特征分析-(6239)

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1、AbstractTianjunNanshaninwesternQinghaiprovinceislocatedintheNorthChinaplate,southernQiliantectonicbeltandthenorthernmarginofthenorthernmarginoftheQaidamBasinbindingsiteZongwulongorogenicbelt.ZongwulongorogenicbeltistheSouthernQilianblockandthenorthernmargi

2、noftheQaidamBasinblockinthePaleozoiccollisionfunctionproduct，NWWdirectionlineartectonicbelt.TianjunNanshanophioliteinQinghaiprovinceinthestudyareaisnotcontinuouslyexposed.EachunitofophioliteinthetectonicrocksheetformoccursinTianjunNanshanophioliticmelangeB

3、elt.Ophiolitesequencethroughouttherockrecoveredisbasicallyintact.TianjunNanshanophiolitebeltisabout19kilometerslong,200~3000meterswide,theexposedareaofabout25squarekilometers.Controlledbyfaults,theNorthLarizhaafaultastheboundarywithsouthernQilianorogenicbe

4、ltinthelateTriassicGroupRivers(Tj)contactwithinfault.OnthesouthsideareinfaultcontactwiththeCarboniferousGuokeshangroup(Cgk)clasticrockandcarbonaterockstrata.TianjunNanshanophioliteassemblagescomposedofdifferentrockblocks,mainlyincludingintenseserpentinizat

5、ionmetamorphosedpureperidotite,peridotite,gabbros,basiclava(deep-seachert)andsiliceousrock.ThebasaltsofTianjunNanshanophiolitebelongtocalcalkalinerock,withthetholeiiteseries,chemicalcharacteristicsoflowKandhighTirocks.Themaficdykesandcumulatesgabbrosbasicl

6、avarockwiththesamechemicalcharacteristics.Metamorphicultrabasichaveperidotitefeaturesoftypicalophiolitein,theircommongeochemicalcharacteristicsreflectingthattheyaremembersofthesameophiolitesuiteinthefamily.Thedifferentrockcombinationproductformationbelongs

7、tothesametectonicenvironment.TianjunNanshanophiolitetotalcontentofREEislow.Metamorphicperidotiteisthelowest,thetotalREEisslightlyhighorclosetomidoceanridgeophiolite.REElineisnotexactlythesameofmidoceanridgeophiolite.TheREElineisclosetooceanislandophiolite.

8、TraceelementsaregenerallyenrichedinLILelements,butlossofHFSelements.8786TheophiolitemaficlavaandmaficdykeswarmsofSr/Sr(0.7037~0.703852)ratioisclosetotheratiooftypicaloceanislandbasalt,andslightlyhigherthanthe