55. Describe three ways to create magma in terms of temperature T and pressure P

Question

55. Describe three ways to create magma in terms of temperature T and pressure P where, in terms of plate a) LowerT 9.Why are mafic rocks like basalt and gabbro dominated by pyroxene, olivine, a) Mafic magmas cool to create granites and thyolites which have these minerals bj Mafic rocks, by definition, are rich in magnesium and iron, so is ej According to Bowens Reaction Series, those minerals melt at similar temperatures, and thus tend to occur c) Raise T (Continental colisions/hot spots): lower P(mid-ocean ridges]; add wates )According to Bowens Reaction Series, those minerals melt at very different temperatures e) According to Bowens Reaction Series, those minerals melt at relatively low temperatures and thus tend to settle to the base of magma chambers 56. 60. Why do intrusive igneous rocks have a course-grained (phaneritic) texture? a) They cooled too quickly for real crystals to form b) They cooled too slowly for large crystals to form c) They cooled slowly allowing time for large crystals to grow d) They cooled slowly and developed a plassy (almost aphanitic) texture. c) igneous rock e) metamorphic rock e) There is limited room in magma chambers for large crystals to grow 57. By what general process did the various igneous rocks in the lithosphere evolve from the original primitive mantle rocks? a) Rocks, in both the mantle layer and the crust, were once molten, Since some rock-forming minerals have lower densities than others, it is normal for solid movement upward toward the surface. Of course, as rocks progress upward, they may metamorphose or they may cause the surrounding crustal rocks to start weathering...the result is a huge variety of different igneous rocks b) Because most crystalline, or igneous, rocks in the earth's crust are composed of many sillicate minerals that melt at similar temperatures, and of minerals with identical crystal lattices, almost all magmas are generated by partial melting c) Magma forms by partial melting of upper mantle and crust. Partial melt means that only a 61. Joe, a geotechnical engineer, must design a foundation for a cabin on a large flat rocky outcrop. In the rock, he can see grains of grey and white translucent reflective minerals some pink grains, and some black dots. A good guess is that the rock is: a) limestone bl shale c) mudstone d) basalt e) granite 62. You have been appointed chief geologist for Project Moho IL, What two plutonic rocks do you expect to encounter as your offshore dri re penetrates through the oceanic crust into melt sinks because of its lower density and descends into the mantle in the earth in the mantle, where minerals with lower melting leave behind quartz crystals, forming basaltic magma. a) basalt and granite b) oore and basalt c) basalt and gabbro like ohne·melt of parent rock e) basalt and peridotite mantle, and many that many basalts may be the result of granites may have derived partly or completely from the partial melting of continental crust 58. Jack has just removed a cauldron of molten magma from a lab furnace and is allowing i to cool very slowly in a pressure chamber. In what order will feldspars begin to solldity? aj Ca-Plag first, folloed by a) Under mountains, near streams, below oceans c) Convergent plate boundaries, oceanic hot spots, subduction zones water, under glacliers, on the land surface di Quartz first, followed by muscovite, orthoclase, blotre, amphibole, pyrosene, and olivine

Explanation / Answer

55. By raising temperature ,lowering pressure and adding water, we can create magma.

56. Igneous rocks forma about 95% of the earth's crust and mantle. so the answer is option c.

57. The answer is option c. The variety of rocks of the lithosphere are from a primitive mantle rock is mainly due to partial melting of mantle rocks.

58. The answer is option d. According to Bowen reaction series, we get to know about the order or rate of crystallization.

59. Mafic rocks are iron and magnesium rich. So, option b is the correct answer.

60. Intrusive igneous rocks cool slowly to allow larger crystals to grow. So the answer is option c.

61. Granite's mineral composition usually gives it a red, pink, gray or white colour woth dark mineral grains. So the answer is e,

62. We will get peridotite and basalt rocks when the drill rig penetrates the upper mantle. Upper mantle contains peridotite, garnet, pyroxene etc.

63. The answer is option d. Volcanoes occur in convergent and divergent boundaries and also above hot spots.

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