20. 20. What type of isneous rocks would be found at location A? a. Basalt b. Ga
ID: 289028 • Letter: 2
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20.
20. What type of isneous rocks would be found at location A? a. Basalt b. Gabbro c. Rhyolite d. Granite Oceanic crust ducting oceanic lithosphere Continental crustA ontinental lithosphere 100 km Asthenosphere Melting 200 km 21 andit movedthroughanoceaniec ust what typeofmagma would the sourceofannagnaisbasa es a. Mafic b. Intermediate c. Felsic Examples of igneous plutons include all of the following except a. batholiths b. dikes c. lava flows 22. 23. What type of volcano produces the most violent and explosive eruptions? a. Shield b. Cinder Cone c. CompositeExplanation / Answer
20. c. Rhyolite Magma
Rhyolitic volcanoes occur in regions of continental crust or in regions of andesitic volcanism. They do not occur on oceanic crust. This implies that continental crust must be involved in the formation of rhyolitic magma.
21. a.Mafic
Basaltic volcanoes occur on both continental and ocenic crust. Basalt (volcanic) and gabbro (plutonic) are virtually the only igneous rocks in the oceanic crust. As the ocenic crust directly overlies the mantle, the source of the magma must be the ultramafic mantle.
22. c. lava flows
A pluton is a body of intrusive igneous rock that is crystallized from magma slowly cooling below the surface of the Earth. Plutons include batholiths, stocks, dikes, sills, laccoliths, lopoliths, and other igneous formations.
23. c. Composite volcano
These highly explosive eruptions are associated with volatile-rich dacitic to rhyolitic lavas, and occur most typically at stratovalconoes. Some of the Earth's grandest mountains are composite volcanoes--sometimes called stratovolcanoes.
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