* Pressure: Metamorphism occurs under increased pressure, usually due to burial under layers of rock.
* Temperature: The temperature range for metamorphism is broad, from relatively low temperatures (around 200°C) to very high temperatures (over 800°C). However, temperatures above 1500°C would likely result in melting, forming igneous rocks instead of metamorphic rocks.
* Fluids: The presence of fluids like water can significantly influence the metamorphic process.
* Time: Metamorphism happens over long periods, allowing minerals to recrystallize and change.
Instead of focusing on a specific temperature threshold, it's better to consider metamorphic rock classifications based on the intensity of the metamorphic process:
* Low-grade metamorphism: Occurs at relatively low temperatures and pressures, resulting in rocks like slate and schist.
* High-grade metamorphism: Happens under higher temperatures and pressures, leading to rocks like gneiss and migmatite.
It's crucial to remember that rocks can transition between different classifications based on the metamorphic conditions they experience.
Therefore, there are no specific metamorphic rocks that form at over 1500 degrees Celsius. At such temperatures, the rock would likely melt and recrystallize into an igneous rock.
