1Igneous RocksIgneous Rocks• Cool from magma• Magma is a mixture of molten rock, solid crystals and dissolved gases• Magma is predominantly silica compoundsNorman Levi Bowen• Experiments of melting igneous rocks• Discovered minerals melt in a distinct and regular order• Hypothesized will crystallize in opposite orderhttp://vgp.agu.org/bowen_paper/bowen_paper.htmlBowen’s lab--1910http://vgp.agu.org/bowen_paper/bowen_paper.htmlBowen’s Reaction SeriesBowen’s Reaction Series• Cooling silicate melt• At certain temperature, a particular set of minerals will crystallize• These will change into different minerals if they remain in contact with magma during cooling phaseBowen’ Reaction Series• At certain temperature, a particular set of minerals will crystallize• Those are the ones present if there is no more magma to solidify• May be removed from remaining magma, so they don’t react with itThe rock cycleRock cycle "shortcuts" or interruptions • Sedimentary rock melts • Igneous rock is metamorphosed • Sedimentary rock is weathered • Metamorphic rock weathers2Sedimentary rock outcrops Sediment deposition Sedimentary rockSedimentary classificationsandstone White cliffs of Doverfossils Dessication cracks Ripple marks3Before deformationGranite and gneissSlate Marble• http://www.carrieresducharme.com/interest.htmFolded rockMetamorphic deformation Fold in metamorphic rockOceanic basin tectonics• http://my.execpc.com/~acmelasr/mountains/geogramsnf.html4Passive continent-to-ocean lithosphere transition• http://www.odp.usyd.edu.au/odp_CD/slope/slindex2.htmlConvergent plate boundary• http://my.execpc.com/~acmelasr/mountains/geogramsnf.htmlRock climbersEl CapitanYosemite mapBasaltic lava splashbasalt Scoria: basaltRhyolite: Fine-grained igneous texture5Coarse-grained igneous texturePorphyritic igneous texturePorphyritic Andesite Porphyritic granite• http://www.soc.soton.ac.uk/soes/resources/collection/minerals/igne-1/pages/ig10.htmObsidian exhibits a glassy texturepumiceClassification of igneous rocksMagma types• Felsic—high silica• Mafic—only about half silica• Intermediate—by mixing of those two• Ultramafic—from mantle meltingMagma components• http://volcanoes.usgs.gov/Products/Pglossary/VolRocks.html6Granite rhyolite basaltgabbro andesiteHornblende phenocrysts in andesite• http://www.pitt.edu/~cejones/GeoImages/2IgneousRocks/IgneousCompositions/5Andesite.htmlPorphyritic Andesite Porphyritic andesite•
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