What are the diverging plates associated with the formation of the galapagos volcanoes?

The Cocos and Nazca plate

Explanation:

As the island is located on the northern edge of the plate Nazca and its currently drifting away from the cocos plate in east and away from pacific place. The islands of Fernandina and Isabela has super bowl morphology along with deep calderas as these all parts of shield volcano system.