Can a metamorphic rock originate from another metamorphic rock?
I know they can originate from igneous and sedimentary.
Yes, metamorphic rocks can indeed originate from other metamorphic rocks. This process is known as re-metamorphism or retrograde metamorphism. It occurs when existing metamorphic rocks undergo further changes in their mineral composition, texture, or structure due to subsequent geological events or changes in environmental conditions.
To understand how a metamorphic rock can originate from another metamorphic rock, we need to consider the process of metamorphism itself. Metamorphism is the transformation of pre-existing rocks due to heat, pressure, or the action of fluids, without melting the rock entirely. During metamorphism, minerals within the rock recrystallize and rearrange to form new minerals, resulting in a distinct metamorphic texture and composition.
In some cases, existing metamorphic rocks can be subjected to additional tectonic forces or undergo changes in temperature and pressure, causing further metamorphic reactions. These changes can lead to the development of a new metamorphic rock, which may possess different characteristics compared to its precursor.
For example, let's say you have a pre-existing metamorphic rock like a gneiss, which forms from the metamorphism of sedimentary or igneous rocks. If this gneiss undergoes subsequent tectonic forces or heat and pressure changes, it can be transformed into another metamorphic rock, such as a schist or a migmatite. In this case, the original metamorphic rock (gneiss) serves as the parent rock for the new metamorphic rock (schist or migmatite) through re-metamorphism.
So, to summarize, yes, metamorphic rocks can originate from other metamorphic rocks through re-metamorphism, where existing metamorphic rocks undergo further changes due to subsequent geological events or changes in environmental conditions.