The Meshik Arc: An eocene to earliest miocene magmatic arc on the Alaska Peninsula

The Meshik arc is herein defined to include Eocene to earliest Miocene volcanic and hypabyssal rocks and the associated Meshik and Stepovak Formations of the central Alaska Peninsula. Igneous rocks range from basalt to dacite and yielded K-Ar ages of 48 to 22 m.y. The Meshik arc is oriented along the trend of the Alaska Peninsula, subparallel to the present-day Aleutian arc. Rocks of the Meshik arc are emplaced on Cenozoic, Mesozoic, and older clastic sedimentary rocks of the Alaska Peninsula terrane. Tectonic interpretation suggests: a) the arc represents a relatively stationary period in the otherwise mobile migration of the Alaska Peninsula terrane, b) subduction was an important process along the Alaska Peninsula during Tertiary time, and c) most migration of the Alaska Peninsula terrane since Cretaceous time took place in Paleocene and middle Miocene time.