1)) Name and describe two mechanisms by which mantle rock can melt without an increase in temperature.

Called as mantel melting

Explanation:

The mantel rocks can break and melt without the increase in temperature due to the overexerted pressure of the rocks. This process is called decompression melting. Rocks can melt in the mantel due to dehydration thus producing molten magma and lava. As the rocks don't melt homogeneously there is a complex mixture of mineral content during the subduction and presence of volatile substances like the water or CO2.