1.
How is magma generated along convergent plate boundaries?
| Friction from the subducting plate raises the temperature of the rock under which it subducts, melting this rock into magma. |
| The subducting plate pushes mantle rock upwards, where it reaches the surface through the trench. |
| The subducting plate drives water and carbon dioxide into the mantle, which reduces the temperature at which it melts, allowing mantle rock to melt and rise. |
| The collision of two continental plates create enough heat to melt rock, thus producing magma. |
| The subducting plate pushes mantle rock upwards, which decompresses as it rises. This decompression allows the mantle rock to melt. |
2.
Volcanism at divergent plate boundaries is most often associated
with which rock type, and what causes rocks to melt in these
settings?
| Volcanism at divergent boundaries is most often associated with felsic rock, which is created by decompression melting. |
| Volcanism at divergent boundaries is most often associated with basaltic rock, which is created by heating of the crust. |
| Volcanism at divergent boundaries is most often associated with basaltic rock, which is created by water lowering the melting temperature of mantle rock. |
| Volcanism at divergent boundaries is most often associated with basaltic rock, which is created by decompression melting. |
| Volcanism at divergent boundaries is most often associated with felsic rock, which is created by water lowering the melting temperature of mantle rock. |
3.
Part A – Choose the answer that does not belong with the
others.
| Shields |
| Lapilli |
| Bombs |
| Pahoehoe |
| Gases |
4.
Select the answer that doesn’t belong with the others.
| Lapilli |
| Basalt plateau |
| Caldera |
| Volcanic neck |
| Lava dome |
Answer
Answer 1: C) The subducting plate drives water and carbon dioxide into mantle, which reduces the temperature at which it melts, allowing mantle rock to melt and rise. Explanation: The melting temperature of a mixture is lower than the melting temperature of a pure melt. In case of convergent boundary, when the denser plate subducts under the lighter plate, it adds third component in the binary component system. In case of subduction zone, generally oceanic plate subducts which adds water and carbon dioxide to subducted lithosphere and mantle. This eventually reduces the melting temperature of the mixture and allow the mantle rock to melt. This process is called flux melting. After melting, the magma rises to the surface of the overridden plate. Answer 2: D) Volcanism at divergent boundaries is most often associated with basaltic rock, which is created by decompression melting. Explanation: In divergent plate boundaries, when two plates move away from each other, pressure is released from the underlying materials and rises upward through process of convection. This lower pressure reduces the melting point of the materials and results into the melting of the rock. This process is called as decompression melting. According to Chegg guidelines, I am supposed to answer the first question only from the multiple questions but here I solved 2 questions. Please make new posts for the remaining questions. Thank you.
