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ID:40848020
大小:1.52 MB
页数:15页
时间:2019-08-08
《Influence of deformation on melt topology in peridotites 变形对橄榄岩熔体结构的影响》由会员上传分享,免费在线阅读,更多相关内容在学术论文-天天文库。
1、JOURNALOFGEOPHYSICALRESEARCH,VOL.102,NO.B5,PAGES10,257-10,271,MAY10,1997InfluenceofdeformationonmelttopologyinperidotitesM.J.DainesandD.L.KohlstedtDepartmentofGeologyandGeophysics,UniversityofMinnesotaatMinneapolis-St.PaulAbstract.Meltmicrostructuresinpartiallymoltenfine-grainedo
2、livine-basaltaggregateshavebeencharacterizedusingimageprocessingmethodstoquantifytheeffectsofdeformationonthegeometryofthemeltnetwork.Olivine-basaltaggregateswithmeltfractionsof0.018to0.165andmeangrainsizebetween10and25gmweredeformedatdifferentialstressesbetween0and250MPa.Forsamp
3、leswithgrainsizesof~10to25gm,deformationatdifferentialstressesgreaterthan~100MParesultsinapreferredorientationofmeltsuchthatalargerfractionofmeltisinmeltpocketswhichhavetheirlongaxisat15-20'toal.Themeltpreferredorientationbecomesmorewelldevelopedwithincreasingdifferentialstressan
4、disrelatedtotheminimuminmeanpressurethatoccursattheendsofmeltpocketsthatareinclinedtoal.Asaresultofthisminimuminmeanpressure,meltflowstotheendsofmeltpocketscausingthemtoextend.Hydrostaticannealingofdeformedsamplesresultsintheredistributionofmeltintomeltpocketsorientedmoreperpendi
5、culartotheoriginal•1;thismeltdistributionisconsistentwiththepreferredwettingof(010)planesofolivinewhichareorientedsubperpendiculartoalafterdeformation.Thedevelopmentofananisotropicmeltdistributioninresponsetostressduringdeformationcouldbeimportantforthefocusingofmelttomid-oceanri
6、dges.IntroductionAlthoughdihedralanglemeasurementsinaggregatesofThephysicalpropertiesofpartiallymoltenrocksdependonolivineplussilicatemeltyieldvalueslessthan60*[Waftandthegrain-scaledistributionofmelt.TheconnectivityandBulau,1979,1982],observationsofsyntheticaggregatesgeometryoft
7、hemeltnetworkaffectnotonlypermeability,producedunderhydrostaticconditionssuggestthatthegeometryrheology,andelectricalconductivityoftherockbutalsoseismicofthemeltnetworkissignificantlydifferentfromthetubulevelocitiesandattenuation.Henceknowledgeofthetopologyofgeometrypredictedbyth
8、eisotropicmodeldescribedabove[Waftthemel
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