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EXPLANATORYTEXT OFTHE GEOLOGICALMAPOFJAPAN Scale ASAHIDAKE Abashiri By MoriakiKōnoyaTakehiroKobayashi CheoulWooKimandShinpeiKawachi GeologicalSurveyofHokkaidō Résumé TheareaofAsahidakesheetmapissituatedinlatitude NandlongitudeE.,andislocatedin thedaisetsunationalparkandbelongstokamikawatownhiga shikawatownbieitownandshintokutowninhokkaidōthe Daisetsuvolcanicgroupisincludedinthissheetmapandthe neighbouringdaisetzusheetmap Topography TopographicallytheareaisdividedintotheDaisetsuvolcanic groupandtheirbasementswhicharedistributedintheeastern andwesternpartsthebasementintheeasternpartismainly composedoftheslateandbasemanyraggedmountainranges peralleltothestructureoftheslatethewesternbasement composedmainlyofthepropyliteshowssteepmountainthe Daisetsuvolcanoesarecomprisetopographicallythebroadrelati velyflatplainscomposedofbasallavaflowsdomeshapedmounta inssuchashakuundakeandtomuraushimadeofveryviscous
lavasandtypicalstratifiedvolcanoessuchasasahidake InadditionlowflatplaneisdevelopedalongtheIshikaririver inthenortheasternpart Geology ThegeologyofthisareaiscomposedlargelyofPreTertiary HidakaGroupMiocenevolcanicrocksandsedimentsandmany lavaflowsofthedaisetsuvolcanicgroupwhichcovertheabove mentionedformationsinadditionquaternarysedimentsare alsopresent PreTertiaryformationisrepresentedbytheslateofthelo werhidakaformationbelongingtothehidakagroup TheMioceneformationscomprisetheKaunnaipropyliteand YanbetappuFormationTheKaunnaipropylitewhichisexten sivelydistributedinthewesternpartoftheareaisakindof compositeigneousbodybeingcomposedofrhyoliticandbasaltic propylitesinsomeplacesbothholocrystallinefaciesandgreen tuffareassociatedwiththem TheYanbetappuFormationislargelycomposedoflatered palegreenweldedtuffsandiscoveredbynormaldepositscompo sedofthesandstonsintheupperhorizon ThePlioceneFormationsincludetheTomuraushiweldedtuff andtheuniishikarilavasthetomutaushiweldedtuffcompo sedofrhyoliticweldedtuffcoveredbytuffaceoussandstoneis welldevelopedinthisareaaswellasintheadjoiningareaofthe sheetmapoftheupperstreamofthetokachirivertheuni Ishikarilavacomposedofthehyperstheneaugiteandesiteisde velopedintheeasternpartofthearea Theothervolcanicrockscomprisethelavaflowsrelatedto theformationofthedaisetsuvolcanicgroupandcanbegrouped intothefollowingstages ThestageoftheformationofthebasementoftheDai setsuvolcanicgroup
ThestageoftheformationoftheOlderDaisetsuVolcano ThestageoftheformationoftheYoungerDaisetsuVo lcano ThestageoftheformationoftheAsahidakevolcano OfthesethestagebelongstothePleoPleistoceneandthest agebelongstotheholocenethelavasofthe stageinclude thebieilowerlavakoganegaharalowerlavanumanoharalava MidoridakelowerlavaKaundakelavaPonchūbetsulavaKogane gaharalavachūbetsudakelavaandtakanegaharalavaallof whicharetwopyroxeneandesitessomtimeswishwelldeveloped platyjointtheyarecharacterizedbytheirextensivedistri butionformingflatlavaplatformsandareofthesocalledflat lavatype The stageincludestheolderdaisetsulavausiroasahidake lavahakuundakelavatomuraushi stlaveandndlavaall ofwhichbelongtothehornblendehyperstheneaugiteandesites withcoarsegrainedphenocrysts ThestagevolcanicsisrepresentedbytheSounkyowelded tuffhyperstheneaugiteandesiticincompositionitsgeologicage isthelatepleistocene InadditionthefirstterracedepositstheHakuyōdairaforma tionandthethirdterracedepositsallofwhicharepleistocene orholoceneinagearedevelopedinthelowlandalongtheishi kaririver GlacialandPeriglacialTopography CirquesduetotheglacialerossionaredevelopedintheKo ganegaharakaundakechūbetsudakeandtakanegaharaandthe iraltitudeishigherthan,mabovethesealevel Periglacialtopographyincludespolygonalsoilsstriationsoils andstonepavementsallofwhicharealsodistributedintheal tiude Economicgeology
Anepithermaldepositofcopperleadandzincisfoundinthe midstreamofthekaunnairiveranexplitationwastried oncebutthedepositwasabandonedowingtoitspoorquality Theminingofsulfurwhichwastheimportantnonmetalicdepo sitsinthecraterofasahidakebeendiscontinued Hotspringsareabondantinthisdistrictandmanyof themareusedforbathingsuchastenninkyōyūkomanbetsu andkogenspashotspringswhichissuefromtheupstreams ofyambetappuandtomuraushirivershavenotbeenutilized EspeciallyalongtheupstreamofTomuraushiriverhotsprings higher aredistributedforthedistanceofaboutkmand muchsteamiscomingout