Here's how it works:
* Heat and pressure: During metamorphism, rocks are subjected to intense heat and pressure.
* Mineral changes: This heat and pressure cause the existing minerals in the rock to become unstable and transform into new, more stable minerals.
* Recrystallization: The new minerals often form larger crystals than the original ones, which can cause the space between grains to change.
* Grain growth: In some cases, the new crystals grow larger and the space between them increases.
* Grain reduction: In other cases, the new crystals are smaller and fill in the space between the original grains, resulting in a tighter texture.
Other factors that can influence the space between grains:
* Chemical reactions: Metamorphic reactions can release or consume fluids, which can affect the porosity of the rock.
* Stress: Differential stress can cause the grains to become elongated or flattened, changing the space between them.
Ultimately, the process of recrystallization is the primary driver of changes in the space between grains in a metamorphic rock.
