Final answer:
A triple junction in plate tectonics is a place where three tectonic plates meet, either at divergent or transform boundaries. It can result in the formation of new crust or rift valleys.
Step-by-step explanation:
In plate tectonics, a triple junction is a place on the Earth's surface where three tectonic plates meet. This can occur at divergent boundaries, where plates are moving away from each other, or at transform boundaries, where plates are sliding past each other. Triple junctions are important because they can lead to the formation of new crust or the creation of rift valleys.