GEOLOGY TEST 1 STUDY GUIDE MINERALS 8 most abundant elements Common ionic form Relative Ionic Size Coordination Oxygen O Silicone Si Aluminum Al Iron Fe Calcium Ca Sodium Na Potassium K Magnesium Mg O 2 Si 4 Al 3 Fe 2 Ca 2 Na 1 K 1 Mg 2 1 4 26 39 63 1 00 99 1 37 72 depends on size 4 4 or 6 6 8 8 8 or 12 6 Crystalline vs Non crystalline A crystalline solid has its molecules or atoms arranged in a lattice That is they are arranged in a regular fashion with equal spacing and angular relationships in all three directions A non crystalline solid also called amorphous has no such regular arrangement of molecules Silicate Minerals olivines Mg Fe 2SiO4 independent tetrahedra pyroxenes Mg Fe 2Si2O6 single chain amphiboles W X Al 7 8 Z4O11 2 OH 2 double chains biotite mica K Mg Fe 3 AlSi3O10 OH 2 sheet silicates muscovite mica KAl2 AlSi3O10 OH 2 sheet silicates quartz SiO2 framework silicates Atomic Ionic substitution in silicates Relationship of cleavage to structure in silicate minerals alkali feldspars KAlSi3O8 NaAlSi3O8 solid solution series framework silicates plagioclase feldspars NaAlSi3O8 CaAl2Si2O8 solid solution series framework silicates Mafic rocks low in silicon Felsic rocks high in silicon EARTH S HEAT Heat Transfer Radiation Electromagnetic waves that directly transport ENERGY through space Conduction transfer of energy through matter from particle to particle Convection transfer of heat by the actual movement of the warmed matter Origin of Earth s Heat comets asteroids and other smaller masses Geothermal Gradient rate at which the temperature increases with depth in the Earth Geobarometric Gradient Melting of Silicate rocks Volatiles water Temperatures of minerals are reduced under high water pressure Wet rocks melt at lower temps that do dry rocks MAGMAS Factors influencing viscosity silica content and temperature Crystallization of magmas Fractional Crystallization Rapid cooling crystal settling or mineral overgrowth inhibiting diffusion prevents melt reacting with crystals Equilibrium Crystallization slow cooling allows previously formed crystals to react with melt to bring them into equilibrium as melt composition changes Magma rise to shallow crustal levels 1 The most obvious is an increase in temperature 2 The introduction of water into rock Water lowers the melting point of rocks 3 A decrease in pressure of rocks that are already hot will cause them to melt Magma originate crust or mantle Volcanic rocks small crystals basalt mafic fine grained dark color andesite intermediate fine grained rhyolite felsic fine grained light color IGNEOUS ROCKS Plutonic rocks large crystals peridotite ultramafic coarse grained gabbro mafic coarse grained dark colored diorite intermediate coarse grained granite felsic coarse grained light colored Textures of rocks Batholith a very large igneous intrusion extending deep in the earth s crust Dike a long wall built to prevent flooding from the sea Extrusive igneous rocks that have been forced out in a molten or plastic condition upon the surface of the earth Intrusive having been forced while in a plastic state into cavities or between layers Pluton body of intrusive igneous rock that is crystallized from magma slowly cooling below the surface of the Earth VOLCANOES Types of Volcanoes Volcanic fields small eruptions occur over a wide area Cone Volcano succession of small moderate eruptions from one location Caldera Volcano infrequent but moderate large eruptions Cinder Volcano steep conical hill with straight sides explosive Shield Volcano very gentle slopes convex upward quiet Strato Volcano gentle lower slopes steep upper slopes concave upward explosive Volcanic Eruptions Hawaiian calmest effusive eruption of very fluid basalt lavas Strombolian bursting of gas bubbles within magma continued activity explosive eruptions Vulcanian highly viscous magma explosive eruption Pelean gas dust ash are blown out of central crater fast moving pyroclastic flow moves down fast Plinian start at magma chamber reaches high in air Eruption Factors 1 the composition of the magma 2 the temperature of the magma and 3 the quantity of dissolved gases contained in the magma Viscosity in eruptions Viscosity is just the ability to resist flow essentially it is the opposite of fluidity If the magma has a high viscosity meaning it resists flow very well Volcano eruption warning signs Rising magma causes solid rock to break sending earthquake signals The cone may start to swell or bulge Lava hot molten or semifluid rock erupted from a volcano or fissure Lava flow a mass of flowing or solidified lava Ash residue left after the burning of a substance Ash flow avalanche of volcanic ash Pyroclastic denoting fragments of rock erupted by a volcano Ash fall airborne ash resulting from a volcanic eruption Mud flow mass wasting involving very rapid to extremely rapid surging flow Lahar a destructive mudflow on the slopes of a volcano Pillow lava lava that has solidified as rounded masses characteristic of eruption under water Shield volcano a broad domed volcano with gently sloping sides characteristic of the eruption of fluid basaltic lava Cinder cone a cone formed around a volcanic vent by fragments of lava thrown out during eruptions Composite Strato Volcano built up by many layers strata of hardened lava tephra pumice and volcanic ash Caldera a large volcanic crater Dome circular mound shaped protrusion resulting from the slow extrusion of viscous lava A a basaltic lava forming very rough jagged masses with a light frothy texture Pahoehoe basaltic lava forming smooth undulating or ropy masses Pumice light and porous volcanic rock formed when a gas rich froth of glassy lava solidifies rapidly Super volcano capable of producing a volcanic eruption with an ejecta volume greater than 1 000 km3 SEDIMENTARY PROCESSES AND ROCKS Chemical Sedimentary rocks Dissolved in waters of the oceans and lakes by chemical weathering Clastic detrital Sedimentary rocks composed of fragments of pre existing rocks Processes that form sedimentary rocks Weathering breaks the rocks into smaller pieces or sediments This can happen by the forces of like wind rain and freezing water Erosion The combination of weathering and movement of the resulting sediments is called erosion Transportation debris from weathered and eroded rocks is moved down hill under the influence of gravity Water is the major agent of transportation Deposition Ultimately sediments are deposited when the agent of transportation
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