 "Wet" igneous rock melts at a lower temperature than the "dry" version of that same rock because the addition of volatiles in "wet" rocks lowers their melting temperature. they occur on the seafloor, where temperatures are already cold. "dry" igneous rocks are made of more felsic minerals. "wet" igneous rocks form at shallower depth in the Earth.The presence of volatiles helps break chemical bonds, resulting in a lower melting temperature for the wet rock. SEC: 4.2 A black, fine-grained tabular intrusion between two layers of horizontal sedimentary rockmust logically be a basaltic sill. granitic sill. basaltic dike. granitic dike.Only basaltic sill fits the description; granite would be light-colored, and a dike would cut acrossexisting layers. SEC: 4.3, Figure 4.9 After an explosive volcanic eruption on an island, the surrounding sea is full of light-grayfloating rock. What must it be? rhyolitepumice obsidian basaltPumice is a felsic, vesicular rock that contains abundant vesicles, which makes it less dense than water. SEC: 4.4, Figure 4.16aAn igneous rock has a medium-gray, fine-grained groundmass with large crystals of plagioclase. Which of the following statements about it is FALSE? It could logically be porphyritic andesite. The lava flow that produced it got quenched in ocean water. The plagioclase crystals are called phenocrysts. It began to crystallize at depth from intermediate-composition magma, then rose to the surface and became a lava flow.Not only would water-quenching create a glassy texture, but this explanation also doesn't touch at all on the origin of the large crystals. SEC: 4.4 Bowen's reaction seriesshows that minerals crystallize in a random order, with no particular pattern involved. allows a geologist to predict what minerals will be found in a given igneous rock. is an attempt to explain the logic of formation of sedimentary rocks. explains why some compounds use ionic bonds and others have covalent bonding.Bowen's reaction series was deduced through laboratory procedures that cooled molten rock; the crystal formation in the igneous rocks produced frequently followed a predictable order. SEC: box 4.1 Bowen's reaction series shows the sequence in which different sulfate minerals form during the progressive cooling of a melt. creates a progressively more mafic melt. has a continuous track in which there is observed a progressive change from sodium-rich to calcium-rich amphibole. was established by laboratory experiments in which mafic melt was quenched in mercury.Bowen's reaction series shows the sequence in which different silicate minerals form (not sulfateminerals) from a mafic melt. Through crystallization of mafic minerals, the melt becomes more felsic (not more mafic). It has both a continuous and discontinuous track, and was developed by lab experiments. SEC: Box 4.1, Figure Bx4.1b Granite is an extrusive igneous rock. is felsic in composition.logically could be found in a lava flow. is the coarse-grained equivalent of andesite.Granite is a felsic, intrusive (and therefore coarse-grained) igneous rock. It is often found as plutons, rather than lava flows (which are extrusive). The coarse-grained equivalent of andesite is diorite. SEC: 4.4, Figure 4.15 How does subduction trigger melting? Flux melting of the asthenosphere above the subducting slab creates a rising melt. The down going slab melts as it reaches hotter temperatures deep in the Earth. The overriding slab insulates the subducting slab, increasing temperature and causing melting. The subducting slab is made of felsic minerals, and therefore melts at lower temperatures.Flux melting (the addition of volatiles) occurs as the down going slab adds water to the surrounding asthenosphere; this acts as a catalyst for melting. SEC: 4.5, Figure 4.4 Identify the FALSE statement. Early Earth had numerous heat sources for igneous activity, including conversion of the kinetic energy of meteorite impact to heat energy. conversion of the kinetic energy of iron alloy sinking toward Earth's center to heat energy. decay of all of its radioactive elements; almost none remain today. the compression of mass into a smaller volume.Radioactive decay was a heat source for early Earth, but it did not exhaust Earth's supply of radioactive elements. There are many radioactive elements left, and they're still decaying and heating Earth's interior. SEC: 4.2 Identify the FALSE statement. Hot solid rock in the Earth may be even hotter than surface lava because of the pressure of overlying rock. may melt if volatiles such as water and carbon dioxide are added. may melt if heat is transferred to it from hot mantle rock rising up into the crust. maintains uniform composition as it melts and becomes magma.Magma composition evolves as rock melts due to partial melting and assimilation processes. SEC: 4.2 Identify the FALSE statement. Large igneous provinces (LIPs) are places where huge amounts of mafic magma have been erupted or intruded. represent special events in Earth's history that may have been caused by super plume activity. occur only along continental margins. may have profound impacts on the environment, including land, ocean, and atmospheric processes.LIPs may occur on the seafloor or on land, along margins, or in the interiors of oceanic plates or continents. SEC: 4.5 Identify the FALSE statement. Pegmatites have intruded at great depth and cooled very slowly. can contain crystals up to tens of centimeters across. occur in tabular intrusions called pegmatite dikes. are an igneous rock type, distinguished by their unusual grain size.Pegmatites have cooled quickly but are, surprisingly, very coarse-grained because they form inwater-rich melts that allow atoms to move around quickly and develop large crystals. SEC: 4.4 Identify the FALSE statement. Magma moves upward toward the Earth's surface because it is less dense than the surrounding rock. slowly, working its way up through cracks and narrow conduits. more quickly as it cools and therefore becomes less viscous. because the weight of overlying rock creates pressure that squeezes it up.The hotter the magma, the less viscous it is and the faster it flows. SEC: 4.3 Interpret this diagram to find the FALSE statement. Point A represents rock that fits the following description. Its temperature is about 1700°C. It is mantle rock. It is under about 100,000 bar (100 kbar) of pressure.