The Peninsular terrane is now part of the crust of North America in southern Alaska. The dominant rock type in this terrane is intrusive igneous rock that ranges in composition from gabbro to granite and volcanic rock with a similar compositional range. Geologic evidence indicates the Peninsular terrane collided with North America during late Mesozoic time. Which of the following would be the most reasonable interpretation for the origins of the Peninsular terrane?

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The presence of intrusive igneous rocks ranging from gabbro to granite and volcanic rocks with a similar compositional range is characteristic of island arcs. These features suggest that the Peninsular terrane was likely a Mesozoic island arc before colliding with North America.

The Peninsular Terrane Is Now Part of the Crust of North