SanFranciscoVolcanicFieldCoconinoHighSchool三藩火山区.pptx

文档介绍：Arizona'sHotspotContinentalHotspotVolcanism:HotspotsarethoughttobecausedbyanarrowstreamofhotmantleconvectingupfromtheEarth'score-prisedofmorethan600volcanoes-mostofthemrelativelysmallcindercones-scatteredoveranareaofabout1,(.,Hawaii,Tahiti).Asaresult,theyarelessexplosivethansubductionzonevolcanoes,,basalticmagmaistrappedinthelessdensecontinentalcrust,,'sHotspotGeologicBackground:positionfrombasalttorhyoliteandbeganactivityabout6,000,,ountain,-chargedfrothyblobsofbasaltmagmaareeruptedasanupwardspray,,-viscosity(andesite)lavaflows,cinders,andash,interspersedwithdepositsfromvolcanicmudflows(lahars),-sidedbulbousmasses(domes),attheeasternoutskirtsofFlagstaff,