GEOL 2312 – Igneous and Metamorphic Petrology Name Key Spring 2009 Sc ore _____/ 40 QUIZ 1 1) of igneous and metamorphic processes? (2 pts) A) Set up experiments to simulate igWhat are two ways that petrologists attempt to overcome the accessibility problem /met processes Develop theortical models to “ etrographic ) observations e two things that petrologists want to know about magmas. (2 pts) , temperature of formation, physical properties (e.g., viscosity) … per sequence – top down (3 pts). B) C) Make interpretations from empirical (field and p2) NamComposition, source material3) Arrange the names of the physical and chemical layers of the earth in their pro Physical Layers Chemical Layers Terms Top Asthenosphere Mantle mantle troposphere Mesosphere Core mesosphere coreore ____________________ lithosphere xenosphere 4) hat ar we can get composit e earth’s mantle?(2 pts) s, Xenoliths, Se Density modellin5) he pro ctonics can ght of as a two stag tion proe Eart l crust. ) Wh in the first stag) Wh in the second s rtant goals of any useful classification scheme for igneous rocks. (2 pts) al e tell us? (1 pt) The manner by which it cooled and ‐ Lithosphere Crust asthenosphere crust Liquid Core ____________________ liquid core solid core Solid CW e two ways that an estimate of the ion of thChondritic Meteorite ismic data, g T cesses of Plate Te be thou e distilla cess to make th h’s continentaA at is distilled e? Mantle (1 pt) B at is distilled tage? Oceanic Crust (1 pt) 6) Name two impoPractical, Descriptive (non‐genetic), Systematic, Heirarchical, Natur7) While the mineralogy of an igneous rock may tell us about the composition of the magma from which it crystallized, what does texturcrystallized. 8) In addition to a modal rock name, name two other descriptors that are useful to completely nerals by which felsic rocks are typically classified (1.5 pts) Quartz, Plagioclase, Alkali Feldspar ing essential mineral (1.5 Fragments/Crystals describing a rock. (2 pts) Alteration, Foliation/Layering, Absolute Grain Size, Bulk Rock Texture –based on pyroxene habit, Accessory/Minor Minerals 9) Name three essential minerals by which mafic rocks are commonly classified (1.5 pts) Plagioclase, Olivine, Pyroxene 10) Name three essential mi11) How do we classify igneous rocks that are too fine‐grained or altered to determine their mineralogy? (1 pt) By their chemistry (e.g. Total Alkali‐Silica plot) or by calculating their CIPWnormative mineral composition from a whole rock analysis and plottcompositions 12) The proportions of what three components are commonly used to classify pyroclastic rocks? pts) Ash/Lapilli/Block&Bombs or Glass/Rock13) Fill in the table below with relative terms of low, intermediate, or high for the physical properties of magmas (3 pts) General Magma Type: Ultramafic Mafic Intermediate Felsic Temperature: High High Int. Low Viscosity: Low Low Int. High Gas Content: Low Low Int. High 14) hat magma type usually erupts effusively? (1 pt) mafic or ultramafic During pressure lowers the solubility (carrying capacity) of water and other volatiles in the magma and causes gas to rapidly unmix from the magma ly composed of basalt whereas stratovolcanoes are composed of a mix of lava and pyroclastic rock types. W 15) What role does magma decompression play in triggering explosive eruptions? (1 pt) eruption, the drop in16) Compositionally, what is a major difference between shield volcanoes and stratovolcanoes? (1 pt) Shield volcanoes are most17) sical features that you mig in a subaeriall pted plateau b (2 pts) Pah flow to es, amygdaloidal/vesicular flow top lumnar joints 18) Name a physical feature that you might find only in a submarine‐erupted basalt. (1 pt) d you most likely find Name two phy ht find y eru asalt. oehoe, AA, e lob s, coPillow structures 19) What is the general rock name for pyroclastic deposits? (1 pt) Tuff 20) For the different intrusion forms listed below, what level of the crust woulthem, the upper crust or the lower crust? (1.5 pts) Dikes and sills Upper Ring Cones Upper Batholith Lower 21) ow might one determine whether an intrusion is syn‐tectonic or post‐tectonic? (1 pt) country rock structures 22) iate attribute of intrusions in the epizone and the catazone of the crust in the table below. (3 pts) Epizone HIn a syn‐tectonic intrusion, the margins of the intrusion tend to be sub parallel to the structure in the country rock; in a post‐tectonic intrusion, the margins com monly cross cut the Circle the appropr Catazone ductile / brittle B) Concordancy of Intrusion Contacts concordant / discordant concordant / discordant 23) into the crust. (2 pts). Stoping, Doming of Roof, Wall rock melting/assimilation, ductile wall rock flow (diapirism), ing 24) ber. What evidence would you look for in an intrusion that would indicate its omposite nature? (1 pt) Abrupt changes in rock type, texture, or composition within an A) Ductility of the Crust ductile / brittle C) Thermal metamorphic gradient strong / weak strong / weak Name a couple mechanisms by which magmas are emplacedemplacement into extensional environment, lateral displacement by folding or fault Large igneous intrusions are typically composite intrusions, formed by multiple injections intothe magma chamcintrusion.