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1、SedimentaryGeology205(2008)160–164ContentslistsavailableatScienceDirectSedimentaryGeologyjournalhomepage:www.elsevier.com/locate/sedgeoDolomiteincaves:Recentdolomiteformationinoxic,non-sulfateenvironments.CastañarCave,SpainAnaM.Alonso-Zarza⁎,AndreaMartín-PérezDpto.dePetrologíayGeoquímica,Fac.C
2、C.Geológicas—InstitutodeGeologíaEconómica,UniversidadComplutense-CSIC,28040Madrid,SpainARTICLEINFOABSTRACTArticlehistory:Dolomiteisacommonmineralintherockrecordbutrareinrecentsuperficialenvironments.WhereitdoesReceived9August2007occur,itisrelatedtoanoxic,sulfate-richenvironmentsandmicrobialacti
3、vity.TheoccurrenceofsomeReceivedinrevisedformdolomitedepositsincaves,however,indicatesthatdolomiteformationisalsopossibleinoxic,non-sulfate26February2008settings.Dolomiteisformingat17°Candinoxic-vadoseconditionsonthehostrocksandaragoniteAccepted29February2008speleothemsoftheCastañarCave,Cácere
4、s,Spain.Itappearsasspheroidsanddumbbells50–300μmindiameterthatinternallyconsistofmicron-sizedrhombictoroundedcrystals.InitiallythisdolomiteisCa-Keywords:Dolomiterich,non-stoichiometricandpoorlyordered.Mg-richsolutionsallowtheprecipitationofmetastableMg-richCavescarbonates,suchashuntite.Thissoo
5、ntransformsintothisCa-richdolomite,whichlater“ages”toformaHuntitemorestoichiometricdolomite.Thesedolomitesshowsimilaritiestothosegrownunderanoxic,sulfate-richLow-temperatureconditionsandtheirpresenceincavesprovidesadifferentsettingthatmaycontributetotheunderstandingRecentofthe“dolomiteproblem”
6、,includingtheirinitialformationandlaterrecrystallizationprocesses.CastañarCave©2008ElsevierB.V.Allrightsreserved.Spain1.Introductionrocksareshalesandgreywackeswithinterbeddeddolostonesandmagnesites(AlonsoZarzaetal.,2005a).DissolutionofthedolomiticDolomiteiscommoninancientmarineandcontinentalro
7、cks,butisbedsandtheextensiveweatheringoftheshalesandgreywackesfavorveryrarelyfoundinrecent,sedimentary,lowtemperatureenviron-collapseswhichcreateandenlargethecavities.Thisdissolutionalsoments.Itsformationinthelaboratoryatlowtemperatures
