Volcanic island arcs and continental volcanic arcs are both associated with convergent plate boundaries. However, the lavas that their volcanoes erupt are different. Where does the lava come from for each type of volcanic arc?
What will be an ideal response?
Answer: Volcanic island arcs are constructed on oceanic lithosphere, which is basaltic. When oceanic lithosphere is subducted and dehydrates, the melt derived from flux melting only interacts with the overlying oceanic lithosphere and remains basaltic. However, continental volcanic arcs will see rising mantle-derived magma assimilate continental material that is more silica-rich. This produces andesitic or even rhyolitic magmas.
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Which of the following processes is the main cause of winter fog?
A. advection of cold air B. uplift C. adiabatic cooling D. radiational cooling
A 1-kg chunk of putty moving at 1 m/s collides and sticks to a 5-kg bowling ball initially at rest. The bowling ball and putty then move with a momentum of
A) 0 kg ? m/s. B) 1 kg ? m/s. C) 2 kg ? m/s. D) 5 kg ? m/s. E) more than 5 kg ? m/s.
The thickest crust is found:a
beneath mountains. b. at the old stable portions of the continents. c. at the continental margins. d. at the old stable portions of the ocean basins. e. at the mid-oceanic ridge spreading centers.
A surface map
A) shows the topography of the land under which weather is happening. B) depicts the general prevailing weather conditions over an area. C) has height contour lines that show wind flow. D) is only used by the television media to lend credibility to their own forecasts.