Geol201 Geology f03 midterm - Your name 201 midterm F2003...

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Unformatted text preview: Your name 201 midterm F2003 class meeting time: 5 Short answer: 4 points each Z 2— Question. Explain why supernovas occur in stars like the one that exploded and gave rise to our solar system. HINT: your answer _.._.—-—-—'—' should BRIEFLY discuss the role of atomic mass/atomic weight 1n fusion reactions. l -. . II I“ ?. f -. I I ‘ '\‘ 11“ .;- h if in. 5. I 6W5! -! C PI!“ .IiI 3 til-55,: r515; use :55-«5 Fe n55 5‘5 ‘5 -‘- 05 first 65 5 5 5 TN ii“. m5 pi [For- ;".;;,5':-5 535311 no €Vlil5'Fi)ILI;](53.145155555552533 Vii €‘Kl‘ifi (‘aLC'H’W‘ sir-.755" ri."5"5.:5’ {'biiiil :flf iud' 5W}? [Ii Di '1) 5FH5WF5 Question: Briefly explain why mosf‘ivater ori Earth lS found directly above oceanic lithosphere. - 5‘ 1'--'" r '. . i 5 5.1 1- .' 55 O[_P-'i.3.l5'fil(ii {.55 5’; l 5 5 5 ’- '. U", _'> (15.;- i‘ 5f "is-[(573 i-‘{.r.5.5't, Question: In thr e sentences or less, explain why magmas becomes more concentrated in silica as they cool and minerals form. "Bullet—type" statements are OK and are encouraged. - 5 5 5- 555 - 5 ’ _,_ . .5 f; : ‘5. n Float? Hoax l3 .3; 53.2 :.' '55 ,- L-t-5; 5.55 3 55 5C. (Li? L r 21' . “xiii. FL»- .J 5 ’ f - .55.: 555' 5 ' 5‘- Flt-:5: 5 .5. 5 15555 ., . ,. ; . 7 II I5 t I; i I . I .. .5 “if! .. h h; a “1055"” 5:" 515' “55‘- 5” . 35' 5.5? f. 5533; “"l-‘F’Vlh Ll} ." l5 . £3, g 3"" 515.5; ; 5?. Question: ' at Mt. Pinatubo had re auve y arg ns in the past? ,5 I II F I , . I; ... , . III; I f . I. _ Ilr f iii-Kw; "ti/Li, 5;: or 5:5 - .5'55'__5;- 55:5 ;299,515“: 5 5 £55.55” .5" . _. d -' .. ~ \. -. -. . . x. . - 5" ‘- i’ii . 535‘» 5"; 5:35" 1 5’5" 5 ”Fifi. in” ii jfl' F55 5 "515 -.- . ' ' l3, 3- " t "‘ F" Iij II<5II I-v’g . II II. "V;- I‘IIIIIIII I:' .J ,f'i-I I I 3 1 I . I 5 E II 'IIFI :. Kiri Lflfl 5 . 5 II " I I . I2“, I , t Question: What process explains the generation of mafic magma from melting of ultramafic rocks? This can be a two word answer (3525 35‘ 552 5“ mr 55.519553 -35 . Question: Please explain how calderas form. a. Question: Why might a change from high 30; emission to low SO; worry scientists monitoring a volcano that is showing signs ofa. major eruption? Question: STUDY THE FIGURE ON THE FOLLOWING PAGE. The next 3 questions refer to that figure 2 points per question. Assign the rocks shown on the following page to one of thed e sitiona] environment listed below: Dry lake ML, (ROCK A. ROCK a IIoerbEnI -: (ROCK A. R’QEL‘BTDR ROCK C) Steep mountain stream ROCK. E! {ROCKR ROCK B. 0R ROCK C) Stream in the gently sloping valley I) Where are oolites found in South Florida and in the Bahamas? 3) Within oolitic limestone b) In underwater dunes c) In rivers @ Bothaandb 2) What catastrophic process distributed relatively heavy elements throughout the interstellar medium. and led to the formation of solar systems like our own? a) subduction b) solar- flare {5" supernova explosion d) radioactive decay 3) Which of the following silicate structures is constitutes (the most silica-rich minerals? ’a isolated tetrahedrons b) Single chain silicates c) Double chain silicates \ . . Sheet silicates 4) What type of cjecta is the main constituent of a composite volcano? a) ash fall deposits b) lava flows Q pyroclastic deposits d) pumice and obsidian 5) Which of the following metamorphic facies indicates high pressure and relatively low temperature? a) greenschist (3} blueschist c) granulite d) amphibolite 6) What causes melting of rocks at subduction zones? a) Transfer of heat from mantle rocks to the subducted plate as the subducted plate enters the mantle wedge. b) Upwelling caused by the plunging of the plate into the mantle wedge @ Fluids from the subducted plate, which lower the melting point of surrounding rocks. :1) pressure on the rocks decreases (decompression). and this allows a phase change. 7) What processes led to melting of the Earth in the early stages of its formation? @ Accretionlrandom collisions, gravitational collapse, and radioactive decay. b) Fusion and accretion c) Accretion and gravitational collapse d) Radioactive decay, fusion. and gravitational collapse 8) Suppose you are studying volcanic rocks that you suspect are a few million years old. The lava that cooled to form the rocks you are studying engulfed a large forest of trees. and there is abunth pieces of charcoal in the rocks you are studying. You are collaborating with a research group that has the capability to use two numeric age dating methods: radioactive decay of carbon 14 ("C: a radioactive isotope with a half life of 5730 years) to nitrogen 14 (“N; a stable isotope); and, radioactive decay of potassium 40 (”K; which is a radioactive isotope with a half life of 1.25 billion years) to argon 40 (”Ar, a stable isotope). To determine the age of the rocks, should you determine the proportion of 1‘C to "N in the charcoal. or should you study the proportion of ”K to ”Ar in the mica present in the volcanic rocks? the proportion of 4"K to It'illtr in the rock should be studied. b) the proportion of “C to “N. 9) What is the role of iron in gravitational collapse of stars? a) iron is a relatively light element. so its presence in stars prevents gravitational collapse of a star. b) iron is a relatively heavy element, so its presence makes gravitational collapse of stars more likely. 0) Iron plays no role in gravitational collapse of stars @ Fusion of iron does not release energy. so when iron fusion commences in stars, disequilibrium ensues. and the ultimate result is gravitational collapse. 10) What is the composition of lava associated with volcanic domes/viscous rhyolitic plugs ? Felsic b Intermediate c) Mafic d) Ultramafic ll) What determines the viscosity of magma? a) The amount of iron and magnesium in the magma G) The amount of silica in the magma c) The amount of LlLs in the magma d) The country rock surrounding the magma chamber 25) Which of the following rock types most likely formed 32) Which of the following metamorphic rocks formed at closest to the source area of sediment? Assume that the the highest temperature and pressure (use the graph at source area of the sediment is a mountain range. right) ? a) Conglomerate FE} Breccia a) a rock that has the mineral glaucophane. c) Sandstone b) a rock that has the mineral actinolite d) Siltstone c) a rock that has the mineral hornblende e) Shale @ a rock that has the minerals pyroxene and garnet 33) Which of the following indicate that Earth’s landmasses 26) What term describes the process by which intermediate- were once connected and formed a “super continent" composition magma is generated from mafia rocks? called Pangea. and have moved thousands of kilometers since then? a) thinning a) The similarity of dinosaur fossils found in areas In reactions separated by great distances. VF)“- sublimation 6 partial melting b) The great diversny of mammals. (1) Global distribution of glacial sediments and ice- sculpted features 27) Which of the following are likely to affect the level of the calcite compensation depth? ‘ a) The temperature of sea water (BF A” Of the above b) Bioproductivity % silica in magma (1) both a and b 28) Which of the following rocks is most likely to have been erupted from an] explosive volcano? @ Rhyolite ‘_/' @ Basalt c) Pillow basalt d) Komatiite Metamorphic facies chart 1'4 29) Which of the following rocks is mot likely to have formed in a magma chamber beneath an explosive volcano? _. M 40 Granite Gabbro E c Breccia x_ d) Peridotite E Please refer to the chart in the right column to answer the a following three questions. 20 30) A regional metamorphic rock contains the mineral hornblende. Where is it most likely that the roek was metamorphosed? - O W PM“ (P N30]: k-blfl a #- 10 Pyroxene a)” A Subduction zone , b) A Mid Ocean ridge/sea floor spreading center e-“zanam ‘ hornfels _ - - -- a ESE “-- 6) AContinent-continentcolltswn 0 400 500 600 700 800 900 1000 pf A Transform boundary _ Tnmncraturc l°Cl 31) A regional metamorphic rock contains the mineral glaucophane. Where was the rock was metamorphosed? ’a”) A Subduction zone :: °° EiAAM C. 0 NT "nuts 0 "‘ N E KT PA GE! d) A Transform boundary ...
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