MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

Transcription

1 Exam Name MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) About 1.2 to 1.0 billion years ago, Canada had a mountain range the size of the modern Himalayas, with high grade metamorphic rocks (>800 C) forming in its roots. Where was this located? A) The Grenville Orogen stretching between Georgian Bay Ontario and Newfoundland B) The Canadian Rockies C) The Trans Hudson Orogen of Saskatchewan and Manitoba D) The Coast Mountains of B.C. 1) 2) Where and how does metamorphism occur? A) wherever solid rocks are subjected to new conditions of temperature, pressure, strain and a change in their constituent fluids B) in response to sudden catastrophic geologic changes, mostly in the Precambrian. C) mainly at low temperatures in the roots of volcanic mountain belts D) beneath the thick accumulations of in sedimentary basins 2) 3) Under the application of uniform, confining pressure, rocks will generally. A) grow or crystallize a new set of low density hydrous minerals B) increase in density but retain primary bedding orientations C) shatter and turn into a breccia D) bend, fold, buckle and shear to make typical deformed metamorphic textures 3) 4) What type of environment is typified by brittle deformation? A) shallow, low temperature settings with high strain rates B) shallow very high temperature settings as in contact metamorphism C) intermediate depths with long slow heating and gradual strain rates D) deep burial with great confining pressure 4) 5) is a strong, parallel alignment of coarse mica flakes and/or of different mineral bands in a metamorphic rock. A) Rock cleavage B) Shear stress C) Foliation D) Brecciation 5) 6) Chemically active fluids like tend to transport ions and mineral components and their activity with increasing temperature. A) HCl and hydrogen sulphide, ceases B) petroleum hydrocarbons, increases C) water and carbon dioxide, increases D) water and carbon dioxide, decreases 6) 7) During metamorphism, what is the major effect of chemically active fluids? A) facilitate the formation of schistosity and gneissic banding in hornfels and slates B) aid in the movement of dissolved silicate constituents and facilitate growth of the mineral grains C) increase the pressures in deeply buried, regional-metamorphic zones D) prevent partial melting so solid rocks can undergo very high temperature regional metamorphism 7) 1

2 8) During metamorphism, what is the major effect of chemically active fluids like water and carbon dioxide? A) prevent partial melting so solid rocks can undergo very high temperature regional metamorphism B) aid in the movement of dissolved ions and silicate constituents from parent minerals and facilitate growth of new metamorphic mineral grains C) increase the pressures in deeply buried, regional-metamorphic zones D) facilitate the formation of schistosity and gneissic banding in hornfels and skarns 8) 9) Which metamorphic reaction takes up water to make hydrous minerals? A) high temperature decomposition of biotite and amphibole to make pyroxene B) contact metamorphism of clays like kaolinite to form sillimanite and corundum C) low temperature alteration of olivine in basalt to form serpentine or talc D) high temperature decomposition of muscovite to form K-feldspar and corundum 9) 10) Which metamorphic reaction liberates water from hydrous minerals to make anhydrous ones? A) high temperature decomposition of muscovite to form K-feldspar and corundum B) high temperature decomposition of biotite and amphibole to make pyroxene C) low temperature alteration of feldspar to form clays or zeolites D) contact metamorphism of clays like kaolinite to form sillimanite and corundum E) both A and B are correct 10) 11) Metamorphic grade refers to. A) how much we'll have to curve your test mark if you are guessing! B) recrystallization versus amount of primary mineral grains C) economic value of metamorphic rocks D) metamorphic intensity as recorded by particular minerals which are sensitive to T,P 11) 12) How would you correctly refer to the metamorphic grade of a rock that contains abundant chlorite as its highest temperature mineral such as a greenschist or phyllite? A) "C grade" B) low grade < 200 C C) high grade > 600 C D) intermediate grade 12) 13) How would you correctly refer to the metamorphic grade of a rock that contains bundles of fibrous sillimanite along with pyroxene and sanidine as its highest temperature minerals such as a coarse grained granulite facies gneiss? A) "S grade" B) low grade < 200 C C) high grade > 600 C D) intermediate grade 13) 14) Where would you expect to find chlorite and zeolites filling up voids and fractures in relatively undeformed rocks? A) burial metamorphism of sedimentary or volcanic rocks B) high temperature hornfels contact metamorphism of salts and rock gypsum C) high grade metamorphism of layered sandstones and shales D) intermediate grade metamorphism of limestones 14) 15) What is the major source of heat for contact metamorphism? A) heat from the spontaneous decomposition of micas and feldspars B) deep burial and heat from Earth's interior C) heat from grinding and shearing on faults D) heat from a nearby magma body 15) 2

3 16) What term describes the zone of contact metamorphism where hornfels forms, surrounding an intrusive magma body? A) oracle B) aureole C) astrobleme D) hydrothermal vein 16) 17) Which of the following best describes the conditions of contact metamorphism? A) Pressures are fairly low, the rock is in the upper part of the crust, the heat for baking the neighbouring rocks is supplied quickly from the intrusion of a nearby magma body. B) Heat is generated very quickly by shearing and mechanical movements along faults. C) Pressures are very high, the rock is deeply buried, and temperatures are raised gradually by Earth's internally generated heat. D) Depths are so deep and temperatures are so high that the rocks begin to partially melt. 17) 18) A large block of sedimentary rock that has fallen into the top of a magma chamber and become metamorphosed is called. A) a roof pendant B) an amphibolite boudin C) an astrobleme D) an inverted aureole 18) 19) is a nonfoliated rock formed by the contact metamorphism of fine grained rocks like shales, mudstones, or volcanics. A) Hornfels B) Gneiss C) Schist D) Marble 19) 20) Which rock forms by contact metamorphism of fine grained mudstones, shales, and volcanics? A) limestone B) gneiss C) hornfels D) phyllite 20) 21) A massive mudstone metamorphosed to biotite hornfels facies would have. A) irregular spots of randomly oriented biotite platelets called porphyroblasts B) biotite defining wavy parallel foliations throughout the rock C) remnants of biotite, now mostly recrystallized to garnet in discreet layers D) breccia of angular biotite clasts crushed and sheared out of shape 21) 22) is a strong, parallel alignment of coarse mica flakes and/or of different mineral bands in a metamorphic rock. A) Foliation B) Stress streaking C) Rock cleavage D) Marbleizing 22) 23) A sillimanite hornfels would. A) lie entirely within the core of the contact aureole occupied by the high grade B) usually form from the complete subduction of ocean crust deep into the mantle C) lie on the outermost edge of a contact aureole where hornfels are preserved D) be formed at the highest grade of regional metamorphism 23) 24) Which two, metamorphic rocks are each composed predominantly of a single mineral? A) garnet schist and andalusite hornfels B) marble and quartzite C) mica schist and granitic gneiss D) fault breccia and graphitic schist 24) 25) is typically formed by metamorphism of a mature sandstone. A) Slate B) Amphibolite C) Quartzite D) Marble 25) 3

4 26) What major change occurs during metamorphism of limestone to marble? A) calcite grains grow larger and increase in size B) calcite grains are dissolved away leaving only marble crystals C) limestone grains react to form quartz and feldspars D) clays crystallize to micas, forming a highly foliated, mica-rich rock 26) 27) Which is a nonfoliated metamorphic rock consisting mostly of calcite? A) hornfels B) gneiss C) marble D) phyllite 27) 28) forms from the metamorphism of limestone or dolostone. A) Marble B) Quartzite C) Amphibolite D) Migmatite 28) 29) The intensity and grade of metamorphism is most intense where. A) cataclastic (dynamic), muds are shattered by raindrop impacts B) contact, clays are recrystallized and reacted entirely to chlorite C) regional, continents collide forming a mountain belt D) burial (zeolite facies), the soil horizon gives way to unaltered bedrock 29) 30) In which setting would regional metamorphism most likely occur? A) at shallow depths below an oceanic ridge or rift zone B) on the rims of large meteorite impact craters C) at great depths in the crust where two continents are colliding D) at shallow depths along major transform faults on the continental crust 30) 31) Which one of the following statements concerning slate is not true? A) forms from shale and mudstones B) has abundant, coarse-grained mica C) sedimentary features may be visible D) rock cleavage is common 31) 32) Which of the following forms at the highest grade of regional metamorphism? A) phyllite B) schist C) slate D) hornfels 32) 33) Which low-grade metamorphic rock, composed of extremely fine mica and other mineral grains, typically exhibits well-developed rock cleavage? A) quartzite B) hornfels C) schist D) slate 33) 34) Which is a foliated, fine-grained regional metamorphic rock formed from mudstone and shale? A) marble B) gneiss C) phyllite D) hornfels 34) 35) What foliated, regional metamorphic rock is texturally intermediate between slate and schist? A) quartzite B) fault breccia C) gneiss D) phyllite 35) 36) Which regional metamorphic rock type listed below represents the highest grade? A) mica schist B) slate C) hornfels D) phyllite 36) 37) Increasing regional metamorphic grade of a shale or mudstone would produce the sequence. A) breccia, gouge, mylonite, ultramylonite B) slate, phyllite, schist, gneiss C) greenschist, amphibolite, granulite D) hornfels, amphibolite, migmatite 37) 4

5 38) Which of the following lists the rocks in the order of increasing grain size and increasing grade for regionally metamorphosed mud rocks? A) phyllite, slate, schist B) slate, schist, phyllite C) slate, phyllite, schist D) schist, slate, phyllite 38) 39) What texture results from the alignment of abundant, coarse-grained, mica flakes in an intermediate grade regional metamorphic rock? A) gneissic banding B) shatter cones C) schistosity D) slaty cleavage 39) 40) What platy, parallel, mineral grains are the most visual aspect of foliated metamorphic rocks? A) carbonates B) feldspars C) quartz D) micas 40) 41) Which is a coarse-grained, high-grade, metamorphic rock with alternating bands or stringers of light and dark minerals? A) marble B) hornfels C) gneiss D) phyllite 41) 42) What do you call a coarse grained, foliated metamorphic rock having thick bands of dark ferromagnesian minerals alternating with pink feldspar and quartz layers? A) schist B) hornfels C) gneiss D) phyllite 42) 43) is characterized by the segregation of light- and dark-coloured minerals into thin layers or bands. A) Garnet hornfels B) Granite gneiss C) Quartzite D) Slate 43) 44) Increasing regional metamorphism of a basalt or gabbro would produce the sequence. A) greenschist, amphibolite, granulite B) hornfels, amphibolite, migmatite C) slate, phyllite, schist, gneiss D) breccia, gouge, mylonite, ultramylonite 44) 45) Amphibolite is a foliated metamorphic rock composed principally of hornblende and plagioclase. How does it form? A) by regional metamorphism of volcanic rocks such as andesite and basalt B) by contact metamorphism of quartzose sandstone cut by a granitic batholith C) by gouging and crushing of limestone along a fault D) by the impact of an asteroid on interbedded sandstone and shale 45) 46) In the formation of migmatites, which minerals start to melt first? A) quartz and feldspar B) amphibole, biotite, and garnet C) zircon and magnetite D) chlorite and calcite 46) 47) is thought to form by partial melting and in situ crystallization of the melted portion at the highest grade of regional metamorphism of crustal rocks. A) Meltite B) Migmatite C) Magmatite D) Magnetite 47) 48) Which of the following rocks would exhibit visible, textural evidence of having undergone significant partial melting? A) migamitites B) coarse grained angular fault breccias C) marbles D) porphyroblastic hornfels 48) 5

6 49) Why is the regional metamorphism of ocean crust in a subduction zone considered separately from regular regional metamorphism? A) the ocean crust has no hydrous minerals to destroy or recrystallize B) unlike regular regional metamorphism, this does not occur on plate margins C) both the basaltic composition and very low geothermal gradient (Low T, Hi P) are unique and lead to different facies than seen in continental rocks D) because this setting does not involve any strain deformation 49) 50) A forms at very high pressures but relatively low temperatures associated with subduction of oceanic crust and sediments. A) blueschist B) migmatite C) mylonite D) sillimanite bearing marble 50) 51) What is the end product (highest grade) reached by subduction zone metamorphism of basalt? A) granulite B) eclogite C) gneiss D) gabbro pegmatite 51) 52) In 1915, which geologist proposed a series of metamorphic facies to describe the progressive mineralogic and textural changes in basalt as a function of temperature and pressure? A) Norman Bowen B) William Logan C) Pennti Eskola D) George Dawson 52) 53) Which facies would you expect to find with high temperature-low pressure contact metamorphism? A) blueschist B) hornfels C) amphibolite D) granulite 53) 54) Which facies would you expect to find with hydrous low temperature-low pressure burial metamorphism? A) zeolite B) blueschist C) amphibolite D) granulite 54) 55) Which facies would you expect to find with intermediate temperature-pressure regional metamorphism? A) blueshist B) hornfels C) granulite D) amphibolite 55) 56) A forms at very high pressures but moderately low temperatures associated with subduction of oceanic crust and sediments. A) blueschist B) mylonite C) biotite marble D) migmatite 56) 57) Which facies would you expect to find with the development of glaucophane at high pressure? A) blueschist B) granulite C) amphibolite D) hornfels 57) 58) are formed from the impact of an asteroid or meteorite. A) Subduction zones B) Batholiths C) Volcanoes D) Astroblemes 58) 59) What are tekites? A) globular to teardrop-shaped, dark, glassy, silica-rich impact melts B) granular breccias produced by fault zone shattering C) hard, foliated, hornfels chips in a shale heated by an intrusive granite D) unusually coarse-grained migmatites that crystallized in a caldera 59) 6

7 60) Tektites originate in what metamorphic environment? A) high temperature melting associated with meteorite impacts B) low pressure and high temperature associated with volcanism C) high temperatures and shearing stresses in an oceanic transform fault D) very high pressures and temperatures associated with deep subduction 60) 61) Which one of the following is not genetically associated with the terrestrial impact of an asteroid or large meteorite? A) blueschists B) tekites C) coesite or shocked quartz D) shatter cones E) impact crater 61) 62) contain the oldest dated metamorphic rocks in Canada. A) The Trans Hudson Orogen B) The Grenville Province C) The Ungava Orogen D) The Acasta Gneiss, NWT 62) 63) Long linear metamorphic fold belts mark. A) divergent plate settings (rifts) B) zones with the lowest geothermal gradients C) the youngest mountains with the slowest rates of uplift D) modern or former convergent continental margins 63) SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question. Match the rock with the appropriate description. A. hornfels B. marble C. gneiss D. phyllite 64) forms by contact metamorphism of mudstones and shales 64) 65) foliated, fine-grained metamorphic rock formed from mudstone and shale 65) 66) nonfoliated metamorphic rock consisting mostly of calcite 66) 67) coarse-grained, metamorphic rock with alternating bands or stringers of light and dark minerals 67) TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false. 68) Most metamorphism happens entirely in the solid state. 68) 69) The type of metamorphic rock that is formed depends on the pressure, temperature, strain rate, fluids and original parent rock composition. 69) 70) Three major factors involved in metamorphism are elevated temperature, elevated pressure, and the chemical action of hot fluids. 70) 71) At elevated pressures, water can be used to supply unequal, directed pressure by hydraulic forces. 71) 7

8 72) Ductile deformation occurs at low strain rates. 72) 73) At high pressures and elevated temperatures of regional metamorphism, silicate rocks are more resistant to flowage and deformation than at low temperatures and pressures. 73) 74) Foliated metamorphic rocks are composed largely of nonequidimensional grains of minerals such as quartz and calcite. 74) 75) During metamorphism, most rock is composed of solid mineral grains, but small amounts of hot fluids or partial melting may facilitate the metamorphic process. 75) 76) Quartzites and metaconglomerates are usually formed along faults by intensive fracturing and fragmentation of conglomerate beds and quartz veins. 76) 77) High-grade, regional metamorphism produces significant and recognizable changes in the textures and mineral compositions of rocks. 77) 78) Muscovite is a hydrous sheet silicate typical of low metamorphic grades. 78) 79) Uniform high pressure metamorphism of a quartz-rich sediment will generate a foliated rock like slate, phyllite or schist. 79) 80) Contact metamorphism is most readily apparent at shallow depths, where the thermal gradients are the steepest (hot intrusion/cold roof rock). 80) 81) Hornfels are metamorphic rocks produced at great depths and high temperatures associated with regional metamorphism. 81) 82) Chlorite hornfels would likely be restricted to the edge of the metamorphic aureole. 82) 83) Calcite is the main mineral constituent of the sedimentary rock limestone and of the metamorphic rock marble. 83) 84) Metamorphic rocks formed during episodes of mountain building typically show textural characteristics indicative of directed pressure and deformation. 84) 85) Rock cleavage or slaty cleavage in slates is largely a consequence of abundant, parallel-aligned, very fine-grained mica flakes in the rock. 85) 86) Muscovite, biotite, and chlorite are common minerals found in phyllites and schists. 86) 87) Slate and schist are both derived by metamorphism of shales and mudstones. 87) 88) The distinctive layers or bands of different minerals in gneisses may be complexly folded. 88) 89) Amphibolites have gneissic textures and form by regional metamorphism of granites and rhyolites. 89) 90) Partial melting is an important process in the formation of migmatites. 90) 8

9 Answer Key Testname: UNTITLED1 1) A 2) A 3) B 4) A 5) C 6) C 7) B 8) B 9) C 10) E 11) D 12) B 13) C 14) A 15) D 16) B 17) A 18) A 19) A 20) C 21) A 22) A 23) A 24) B 25) C 26) A 27) C 28) A 29) C 30) C 31) B 32) B 33) D 34) C 35) D 36) A 37) B 38) C 39) C 40) D 41) C 42) C 43) B 44) A 45) A 46) A 47) B 48) A 49) C 50) A 9

10 Answer Key Testname: UNTITLED1 51) B 52) C 53) B 54) A 55) D 56) A 57) A 58) D 59) A 60) A 61) A 62) D 63) D 64) A 65) D 66) B 67) C 68) TRUE 69) TRUE 70) TRUE 71) FALSE 72) TRUE 73) FALSE 74) FALSE 75) TRUE 76) FALSE 77) TRUE 78) TRUE 79) FALSE 80) TRUE 81) FALSE 82) TRUE 83) TRUE 84) TRUE 85) TRUE 86) TRUE 87) TRUE 88) TRUE 89) FALSE 90) TRUE 10