* An igneous intrusion (like a pluton or dike) and a pre-existing sedimentary or metamorphic rock.
Here's why:
* Igneous intrusions: These are hot, molten rocks that rise up through the Earth's crust. When they come into contact with existing rocks, the heat from the intrusion will bake the surrounding rocks, changing their mineralogy and texture.
* Pre-existing rocks: These can be sedimentary rocks (like sandstone, limestone, or shale) or metamorphic rocks (like slate, schist, or gneiss). These rocks are generally much cooler than the igneous intrusion.
Example:
Imagine a large mass of granite (an igneous rock) rising up through layers of limestone (a sedimentary rock). The heat from the granite would bake the limestone, causing it to recrystallize and potentially form marble (a metamorphic rock). This zone where the limestone is transformed into marble is the contact metamorphic zone.
Important note: While the most common scenario involves igneous intrusions and other rocks, contact metamorphism can also occur where two different metamorphic rocks with contrasting temperatures come into contact. However, this is less common than the igneous intrusion scenario.
