Impact of post-depositional processes on charcoal fragmentation and archaeobotanical implications: Experimental approach combining charcoal analysis and biomechanics

Julia Chrzazvez (1) , Isabelle Théry-Parisot (1) , Gilbert Fiorucci (2) , Jean-Frédéric Terralc (3) , Bernard Thibaut (4, 5)

1 CEPAM - Centre d'Études Préhistoire, Antiquité, Moyen-Age
2 CEMEF - Centre de Mise en Forme des Matériaux
3 UMR ISEM - Institut des Sciences de l'Evolution de Montpellier
4 LMGC - Laboratoire de Mécanique et Génie Civil
5 BOIS - Bois

Generallyspeaking,charcoalanalysisisbasedonidentifyingandcountingcharcoalfragmentsinordertocalculatetherelativevariationsintaxafrequency.Allpost-depositionalprocessesarelikelytoinducefragmentationoftheanthracologicalmaterial,raisingthequestionoftherepresentativenessoftaxa.Basedonaninnovativeexperimentalapproachcombiningbothcharcoalanalysisandbiomechanics,thispaperexploreshowthemechanicalpropertiesofcharcoalcaninfluencethefragmentationandthequantificationofspeciesinanthracologicalassemblages.Wecarriedoutstandardizedlaboratorycompressiontestson302samplesissuedfrom10taxa,charredatthreedifferenttemperatures,inordertocharacterizethemechanicalpropertiesofcommonspeciesintemperateandMediterraneanEurope.Ourresultshighlightthedifferentialresponsesofthetestedspeciesintermsofresistancetocompressionandfragmentation,twoprocesseswhichdonotappeartobecorrelated.Charcoalisveryresistanttopressure(upto22.5MPa).Ourresultsshowthatsignificantfragmentationdifferencesexistbetweentaxa.Thetotalnumberoffragmentsaftercompressionislargelydependentonthespecies,regardlessofthecharringtemperature.However,thisinterspecificvariabilityismoresignificantforsmallfragments[1e2mm],thanforlargerfragments[2e4mm]and>4mm,withtheexceptionofQuercus,whichdisplaysdifferentialreactionstocompression.Finally,amultifactorialanalysisbringstolighttheimpactofthephysicalandanatomicalcharacteristicsofthedifferentspeciesoncharcoalfragmentation

Keywords: Experimentation; Fragmentation; Charcoal analysis; Taphonomy; Mechanical properties

Domains: Materials; Biodiversity; Environmental Sciences

Julia Chrzazvez, Isabelle Théry-Parisot, Gilbert Fiorucci, Jean-Frédéric Terralc, Bernard Thibaut. Impact of post-depositional processes on charcoal fragmentation and archaeobotanical implications: Experimental approach combining charcoal analysis and biomechanics. Journal of Archaeological Science, 2014, 44, pp.30-42. ⟨10.1016/j.jas.2014.01.006⟩. ⟨hal-00951096⟩