A metamorphic process dominated by high differential stress and deformation without necessarily high temperature is called which type?

A metamorphic process dominated by high differential stress and deformation without necessarily high temperature is called which type?

• A. Contact metamorphism
• B. Regional metamorphism
• C. Dynamic metamorphism
• D. Hydrothermal metamorphism

Answer: (C)

This item tests understanding of metamorphism by the condition that mainly drives the change. When rocks are squeezed and deformed under high differential stress, with deformation playing the primary role, the metamorphism is dynamic (also called cataclastic) metamorphism. It often occurs in fault zones where rocks experience directed pressure as they are sheared, and the temperatures may not be very high. The textures formed reflect the deformation—fabrics created by grinding and crushing of grains rather than new minerals formed by heat. In contrast, contact metamorphism is driven by high temperature from nearby magma, typically localized and heat-dominated; regional metamorphism involves large-scale high temperature and pressure from burial and tectonic thickening, not just deformation; and hydrothermal metamorphism is governed by hot fluids altering minerals chemically, with deformation being a secondary, not primary, factor.

This item tests understanding of metamorphism by the condition that mainly drives the change. When rocks are squeezed and deformed under high differential stress, with deformation playing the primary role, the metamorphism is dynamic (also called cataclastic) metamorphism. It often occurs in fault zones where rocks experience directed pressure as they are sheared, and the temperatures may not be very high. The textures formed reflect the deformation—fabrics created by grinding and crushing of grains rather than new minerals formed by heat.

In contrast, contact metamorphism is driven by high temperature from nearby magma, typically localized and heat-dominated; regional metamorphism involves large-scale high temperature and pressure from burial and tectonic thickening, not just deformation; and hydrothermal metamorphism is governed by hot fluids altering minerals chemically, with deformation being a secondary, not primary, factor.