Influence of deformation on melt topology in peridotites 变形对橄榄岩熔体结构的影响

《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