Midterm 2 Study Guide for The Planet Earth | EPS 50, Study notes of Environmental Science

Download Midterm 2 Study Guide for The Planet Earth | EPS 50 and more Study notes Environmental Science in PDF only on Docsity! EPS 50 Spring 2011, Midterm 2 Review I. Rocks A. Igneous rocks are formed by cooling and solidification of magma. a. Composition i. Felsic: light, highest silica content, low Mg- and Fe-containing minerals, low density e.g. Granite ii. Intermediate: grey, mix felsic + mafic e.g. Andesite iii. Mafic: dark, low silica content, high Mg- and Fe-containing minerals, high density e.g. Basalt iv. Ultramafic: dark, lowest silica content, high Mg- and Fe- containing minerals especially olivine e.g. Peridotite b. Texture i. Intrusive: magma slowly cools and solidifies within the crust thus rocks are coarse-grained e.g. Granite ii. Extrusive: magma quickly cools and solidifies at the Earth’s surface thus rocks are fine-grained e.g. Basalt B. Sedimentary rocks are formed when sediments are deposited out of wind and/or water and transported to the depositional areas. These sediments then get converted into sedimentary rocks though physical and chemical changes e.g. compaction and cementation…this process is called “diagenesis”. a. Composition i. Siliciclastic: quartz, feldspars, clays ii. Carbonate: calcite, dolomite iii. Evaporite: halite, gypsum, anhydrite b. Texture i. Clastic: discrete, solid particles derived from weathering and erosion e.g. Sandstone ii. Biological: accumulation of skeletons from microorgnisms e.g. Chert (silica-rich), Limestone (carbonate-rich) iii. Chemical: minerals in the solution become supersaturated and get precipitated out e.g. Evaporite C. Metamorphic rocks are formed by physical and chemical changes (e.g. pressure, temperature, influx fluids) of pre-existing rocks. a. Composition: common minerals are feldspars, pyroxene, garnet, glaucophane, kyanite b. Texture i. Foliated: non-uniform pressure is applied creating wavy, banding texture e.g. Gneiss ii. Non-foliated: uniform pressure is applied to all sides e.g. Marble c. Types of metamorphism i. Regional metamorphism is due to a collision of two continental plates (e.g. subduction zone, mtn. building), which produces high P but relatively low T in rocks e.g. Blueschist, Eclogite ii. Contact metamorphism is a result of an intrusion of hot magma into cooler native rocks (high T, low P) e.g. Hornfels iii. Shock metamorphism occurs when a meteorite hits the Earth’s surface (ultrahigh P with moderate T) e.g. Coesite, Stishovite iv. Hydrothermal metamorphism is a result of the interaction of a rock with a high T fluid e.g. Sulfides, Serpentine v. Burial metamorphism occurs in deep basins (> 10 km) where T and P are great enough to metamorphose rocks e.g. Zeolites. d. Prograde and Retrograde metamorphism Prograde involves the change of mineral assemblages as well as the loss of water and CO2 with increasing T and P while Retrograde is the reconstitution of a rock under decreasing T and P, allowing the mineral assemblages formed in prograde metamorphism to revert to those more stable at less extreme conditions. II. Deformation (CHAPTER 7) A. Forces (pg. 168) Understand convergent and Divergent plate boundaries and the associated deformation - Tensional Forces – divergent boundaries, stretching, normal faults - Compressive Forces – convergent boundaries, squeezing and shortening, reverse faults - Shearing Forces – transform-fault boundaries, offsetting of material B. Deformation Structures - Faulting occurs when material is brittle (low confining pressures) (pg. 172- 174) o Normal Fault/Dip Slip o Reverse Fault/Thrust o Strike-Slip Fault - Folding occurs when material is more ductile (high confining pressures) (pg. 175-177) o Anticline o Syncline o Tilted layers C. Hydrocarbon traps - stratigraphic - structural