Describe two mechanisms by which mantle rock can melt without an increase in temperature

Mantle rock can melt without an increase in temperature if there is a decrease in pressure exerted by overlaying rock layers. This is called decompression melting. Rocks can also melt in the mantle due to dehydration. A subducting slab carries with it water as it is pulled into the mantle. The gradual release of the water contained in the slab is the mechanism that causes melting. 

980 is the correct answer

Answer meranesia;