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1、JournalofStructuralGeology22(2000)1723±1735www.elsevier.nl/locate/jstrugeoMolluscshellmicrostructuresandcrystallographictexturesD.Chateignera,*,C.Hedegaardb,H.-R.WenkcaLaboratoiredePhysiquedel'EtatCondenseÂ,UniversiteÂDuMaine,LeMans,FrancebInstituteofBiology,DepartmentofEcologyandGenetics,Universi
2、tyofAarhus,Aarhus,DenmarkcDepartmentofGeologyandGeophysics,UniversityofCalifornia,Berkeley,CA,USAReceived30November1999;accepted26June2000AbstractX-raydiffractionisusedtocharacterisetexturesofthearagonitelayersofshellsfrommonoplacophoras,bivalves,cephalopodsandgastropods.Texturesvaryinstrength,pat
3、ternandthroughthethicknessoftheshells.Thetexturepatternsexhibitedinthestudiedtaxa,whichcanbequantitativelydescribedbyalimitednumberofparameters,arecomparedwiththemicrostructuretypesobservedwithscanningelectronmicroscopy.Whereasforsimplecrystallitearrangements,suchasnacres,thereisagoodcorrespondenc
4、ebetweentextureandmicrostructure,thisisoftennotthecaseinmorecomplexmicrostructuressuchasincrossedlamellarlayers.Morphologicallysimilarmicrostructuresmayhavedifferentcrystallographictextures,andthesametexturesmaybefoundinmicrostructureswithdifferentmorphol-ogy.Thesetwokindsofmeasurementsareshowntob
5、ecomplementarysincetheyprovidenon-redundantinformationformanytaxa,whichsuggeststhattheymaybevaluablephylogeneticindicators.q2000ElsevierScienceLtd.Allrightsreserved.1.Introductiondominatestheanisotropicpropertiesofaggregates(Kocksetal.,1998).However,onlyfewpapersconsidertheaggre-Theinvestigationof
6、molluscshellmicrostructures,builtgatepropertiesofshells(Bùggild,1930;Wenk,1965;ofcomplexcalciteand/oraragonitelayerintergrowths,isofWilmotetal.,1992).Mutvei(1978,1980)hypothesisedinterestinmany®eldsofscience.Ingeology,sinceshellsaboutthecrystallographicpropertiesofnacretablets,butarethemostcommonl
7、ypreservedpartsinfossils,theyarehisconclusionshavebeenatleastpartlyrefutedbyrecentusedtodeterminethephylogeneticevolutionandspecifyinvestigations(HedegaardandWenk,1998).thestratigraphicageofgeologicalformations.P
