1The Rock CycleReading: Pages 51-78Review Questions Ch 3: 1-5, 17, 18 The rock cycleRock cycle Shows the interrelationships among the three rock types IgneousSedimentaryMetamorphicLavasediment Sedimentary rock2Metamorphic rock Convergent lava generationPlutonic rock genesis Rock cycle Full cycle does not always take place due to "shortcuts" or interruptions • Igneous rock is metamorphosed • Sedimentary rock is weathered • Metamorphic rock weathers Igneous rocks Magma cools and crystallizes • Inside Earth -- plutonic or intrusive rocks • On the surface --volcanic or extrusive rocksFormed from lava (a material similar to magma, but without gas3Scaling El Capitan El CapitanIgneous textures Crystallization of magmaIons become crystals Crystal size is determined by the rate of cooling • Slow = large crystals • Fast = microscopic crystals • Very fast= no crystals-- forms glass Coarse-grained igneous textureCoarse grained4Fine-grained igneous textureFine grained andesitePorphyritic igneous textureporphyriticGlassy texture Pumice5VesicularTextureSize and arrangement of crystals • Fine-grained – fast rate of cooling• Coarse-grained – slow rate of cooling • Porphyritic (two crystal sizes) – two rates of cooling • Glassy – very fast rate of coolingClassifying Igneous Rocks•Texture• Mineral contentFelsic rocksComposed almost entirely of light-colored silicates - quartz and feldspar • Felsic: feldspar and silica (quartz)• High silica content (about 70 percent) • Common rock is granitegranite rhyolite6Mafic rocksContain substantial dark silicate minerals and calcium-rich plagioclase feldspar •Mafic: magnesium and ferrum (iron) • Common rock is basaltbasaltgabbro Intermediate rocks• Mixture of magmas• Less common than basalt or granite• Andesite and Dioriteandesite diorite7Classification of igneous rocks based on texture and mineral constituentsIgneous rock classification chart with photos of rocksMineral composition• Explained by Bowen's reaction series which shows the order of mineral crystallization • Influenced by crystal settling in the magmaBowen’s reaction seriesMagma body before settling Crystal settling8More crystal settling Most common igneous rocks• Granite• BasaltMineral resources • Reserves are already identified deposits• Ores are useful metallic minerals that can be mined at a profit • Economic factors may change and influence a resource Metallic mineral resources • Gold, silver, copper, mercury, lead, etc. • Concentrations of desirable materials are produced by • Igneous processes • Metamorphic processes• Sedimentary processes Hydrothermal (hot-water) fluids from magma bodies Metallic mineral resources •Hot water• Contain metal-rich fluids• Associated with cooling magma bodies• Types of deposits include • Vein deposits in fractures or bedding planes, and • Disseminated deposits which are distributed throughout the rockThe Bingham copper mine in Utah9Nonmetallic mineral resources • Make use of the material’s • Nonmetallic elements • Physical or chemical properties• Two broad groups • Building materials (e.g., limestone, gypsum) • Industrial minerals (e.g., fluorite, corundum, sylvite) An underground halite (salt)
View Full Document
Unlocking...