简介：X-raydiffractionmethodsforestimatingthemetamorphicgradeofdiagenetic,anchizoneandepizoneinmetapelitesarereviewedandappliedtosamplesfroma7000m+boreholeinwesternChinaandsurfacesamplesfromthesurroundingZoigêarea.Kübler'sillitecrystallinity(IC)measurementsprovidemoreconsistentresultsthancalculatedvaluesofpercentageofilliteintheI/SmixedlayersandpercentageofI/Smixedlayers.Down-boreholeICvaluesdisplayatypicalburialmetamorphicrelationshipbetweenstratigraphiclevelandIC.Amethodforpreparingverylowgrademetamorphicmapsisdescribed,andisogradsplottedonaregionalgeologicalmapatselectedvaluesofIC,delineatingahightemperaturediageneticzone,ananchizone,andanepizone.ThemapshowsthatICvaluesarecontrolledbystratigraphiclevelinthenorthofthestudyarea(i.e.burialmetamorphism),andproximitytoanigneousintrusivebodyinthesouth(i.e.contactmetamorphism).