Which type of metamorphism occurs when rock is subjected to direct heat and pressure?

The correct type of metamorphism that occurs when rock is subjected to direct heat and pressure is contact metamorphism. This process generally takes place when magma intrudes into cooler surrounding rock, causing localized heating and alteration, which results in the metamorphism of the adjacent rock.

Contact metamorphism typically affects a relatively small area of rock and involves a higher temperature gradient compared to the broader pressures associated with regional metamorphism. The heat from the magma and the pressure exerted during this process modify the mineral composition and texture of the surrounding rocks, leading to the formation of new metamorphic rocks.

In contrast, regional metamorphism is usually associated with large-scale tectonic forces and is characterized by both heat and pressure over extensive areas, often linked to mountain-building events. Hydrothermal metamorphism involves hot, mineral-laden waters altering rocks, while dynamic metamorphism occurs mainly along fault lines where pressure is applied rapidly without significant heat, resulting in the formation of mylonites. Understanding the conditions under which each type of metamorphism occurs helps highlight the specific processes and environments responsible for the changes in rock characteristics.