Geology Exam 2: Minerals, Rocks, and Earthquakes - Prof. John Alan Chermak, Study notes of Geology

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Geology – Exam 2 Study Guide Minerals and Rocks - Sustainability – meeting today’s needs without compromising the ability to meet needs in the future - many companies are leading the way in sustainability because they are only buying materials that are taken from the earth correctly - Loma Preitar – 7.1 on the Richter scale - epicenter was located at Santa Cruz - not vertical strike slip like expected - 18 kilometers down (deep for California) - 8 seconds of shaking - Mineral Dust: - Fine grained mineral particles that get into lungs, generally harmless Asbestos – a broad commercial term for a group of naturally occurring hydrated silicate minerals that crystallize in a fibrous habitat, collagen deposition caused by chronic inflammation reduces the flexibility of lung tissue Mesothelioma – malignant tumor growth in lining of chest and abdominal cavity - Diamonds are presently being mined in igneous rocks and sedimentary rocks - a mineral is crystalline (containing a crystal lattice) while a glass is not - Chemical Classification of minerals based on Anions: - silicates +/- aluminum rich (continental) - oxygen and silicon make up 70% of the weight of the continental crust - feldspar – account for 60% of all the minerals in the continental crust - muscovite mica (potassium rich) - iron magnesium rich (oceanic) – denser and more heavy than silicates - olivine – magnesium + silica or iron + silica - pyroxene group – single chain silicate – the tetrahedron link to form a chain by sharing two oxygen atoms each, two cleavage directions at 90° to each other - amphibole group - double chain silicate – tetrahedron link to form a double chain by sharing two or three oxygen atoms, two cleavage directions at 60° to each other - biotite mica – sheet silicates – single strong cleavage in one direction, all share three oxygen atoms and therefore link to form two-dimensional sheets - 50% of earth’s crust is Calcium and Sodium rich feldspar and potassium rich feldspar - Chemical classification of Minerals: - Native elements – pure masses of a single metal (gold and copper), can charge themselves - Sulfides – metal cation bonded to a sulfide anion (have a metallic luster) - Pyrite - FeS2 - Oxides and Hydroxides – metal cations bonded to oxygen anions (both examples are rusts) - Hematite - Fe2O3 - Goethite - FeO(OH) - Hywasy, VA – pure iron deposit used to make colors for crayons -Carbonates – calcium and magnesium bond to this group - Calcite – CaCO3 - Sulfates – metal cation bonded to SO4 anionic group - form from precipitation out of water at or near the Earth’s surface - used to make sheetrock - Gypsum – CaSO4·2H2O - Halides – the anion is a halogen ion (such as chlorine or fluorine) - Halite (rock salt) – NaCl - Physical Properties of Minerals: - Density – mass/volume - specific gravity- density of a mineral as specified by the ratio between the weight of a volume of the mineral and the weight of an equal volume of water at 4°C - Low temperature materials – light color and continental material - felsic – silica rich (less dense), white (Rhyolite and Granite) - high viscosity (resistant to flow) - potential for explosive eruption - quartz, feldspar, muscovite - Intermediate –between that of felsic and mafic (Andesite and Diorite) - Rocks to Know 1.) Gabbro – oceanic, iron rich, phaneritic 2.) Basalt – oceanic (most abundant), iron rich, aphanitic, most common kind of extrusive rock (1 and 2 are same minerals) 3.) Diorite – from explosive volcanoes, fine grain, fast cooled 4.) Andesite – from explosive volcanoes, fine grain, fast cooled (3 and 4 are same minerals) 5.) Granite – course grain, rich in quartz and silica 6.) Rhyolite – fine grain, rich in quartz and silica (5 and 6 are same minerals) - Rhyolitic magma – abundant on the continental crust - Andesitic magma – occur on both oceanic and continental crust, a line around the pacific separate andesitic volcanoes from those that erupt only basaltic lava - Basaltic magma – occur on both oceanic and continental crust, source must be the mantle, volcanoes along the midocean ridges erupt basaltic magma, Hawaiian volcanoes Earthquakes - subduction zones have the quakes - Spheres: - biosphere – the region of the earth and atmosphere inhabited by life, this region stretches from a few kilometers below the earth’s surface to a few kilometers above - atmosphere – the layer of gases that surrounds the planet - lithosphere – the relatively rigid, non-flowable, outer 100- to 150-km-thick layer of the earth, constituting the crust and the top part of the mantle - hydrosphere – the earth’s water, including surface water, groundwater, and liquid water in the atmosphere - seismology – the study of ground motion - the more dense the material, the faster the velocity of the P-waves - Deformation: - stress – force/unit area - strain – change in shape that deformation causes - elastic – when stress is removed, object bounces back - brittle – past the elastic limit, object breaks, associated with the release of energy which is transmitted by waves - plastic – flows - faults – surface where relative movement has occurred - epicenter - surface right above the focus Waves: - primary – compression and expansion (fastest and first) - secondary – perpendicular to wave direction (cannot travel through liquid) - surface – emanates from epicenter (slower then p and s-waves but causes most damage) Magnitudes: - Richter Scale – based on recorder height/amplitude on seismograph - each unit increase, represents approximately a 30 times increase in energy Intensity: - there are I – XII degrees of intensity in the modified Mercalli scale - Moho – researcher who noticed that an earthquake waves velocity increased at about a depth of 50 km, and it was suggested that this increase was caused by an abrupt change in the properties of rock, brought about the crust-mantle boundary which is now referred to as the Moho, seismic discontinuity that marks the base of the crust Periodic Table - left side – positively charged (cations) - right side – negatively charged (anions) - oxygen is the most abundant anion and has the purest negative charge - sodium + chlorine = table salt -SiO2 = quartz - Al2O3 = aluminum - Silica Tetrahedron – (SiO4) 4- - building block for most minerals - most abundant mineral in Earth’s crust Nuclear Energy - US is 13” behind in rainfall (drought) - 1/3 of Virginia’s electricity is nuclear - is 20% of US’ source of electricity - Uranium deposit on a farm in Chatham, Virginia worth $10 billion - Disasters: - Chernobyl, Ukraine in 1986: - runaway chain reaction and graphite core burned - many western European countries are in the process of phasing out nuclear power - flawed reactor design, inexperienced workers, and a power surge led to the explosion, core meltdown and the release of high levels of radioactivity and radioactive Iodine gas which concentrates in your thyroid - Three Mile Island, Pennsylvania in 1979: - mechanical and electrical malfunctions, combined with human error led to a release of a small amount of radioactive xenon gas