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1、PALEOCEANOGRAPHY,VOL.27,PA2206,doi:10.1029/2011PA002271,2012OriginofmagneticmineralconcentrationvariationintheSouthernOcean12ToshitsuguYamazakiandMinoruIkeharaReceived21December2011;revised10March2012;accepted13March2012;published24April2012.[1]IntheSouthernOcean,magneticmineralconcentrationi
2、ncreasesinglacialperiods.ThevariationpatterncloselyresembleseoliandustfluxrecordsfromAntarcticicecores,butthecauseofthelinkageremainsunclear,asthedustfluxistoosmallforthesourceofterrigenousmaterialsintheSouthernOcean.WehaveconductedanenvironmentalmagneticstudyoflatePleistocenesedimentsfromthe
3、southIndianOceantoinvestigatetheoriginofthemagneticconcentrationchanges.Biogenicmagnetitescanbedetectedusingthecharacteristicsofalmostnomagnetostaticinteractionsandnarrowcoercivitydistribution,reflectingoccurrenceofsingle-domainmagnetitesinachain.Weinterpretthatanon-interactingcomponentonfirs
4、t-orderreversalcurvediagramsandlow-coercivitycomponentswithsmalldispersionfromisothermalremanentmagnetization(IRM)componentanalysesrepresentbiogenicmagnetites,andthattheinteractingandmiddle-coercivitycomponentsrepresentterrigenousmaghemites.Theratioofanhystereticremanentmagnetizationsusceptib
5、ilitytosaturationIRMreflectsrelativeabundanceofthebiogenicandterrigenouscomponents.Itwasrevealedthatbiogenicmagnetitesareadominantconstituentofthemagneticminerals.Inglacials,theabundanceofbothbiogenicandterrigenouscomponentsincreasedwithincreasedproportionsofthelatter.Increasedoceanproductivi
6、tyinglacialsissuggestedfromincreasedproportionsofbiogenicmagnetiteswithelongatedmorphologies,indicativeofless-oxicconditions,andincreasedsedimentationrates.TheseobservationssuggestthattheincreasedmagneticconcentrationinglacialsintheSouthernOceanmaybeexplainedbyironfertilization;theproductiono
7、fbiogenicmagnetiteswasenhancedassociatedwithincreasedoceanproductivity,whichwasfueledbyincreasedeoliandustflux.Citation:Yamazaki,T.,andM.Ikehara(2012),OriginofmagneticmineralconcentrationvariationintheSouthernOcean,Paleoceanography,27,PA2206,
