The origin of the Bering Sea basalt province, western Alaska

Bering Sea basalt province consists of at least 15 late Cenozoic (less than 6 Ma) volcanic fields that occur on islands in the Bering Sea and along the adjacent west coast of Alaska. The fields are composed of widespread flows of tholeiitic and alkali olivine basalt and small cones, flows, and maar craters of more alkalic basalt, basanite, and rare nephelinite. Although the volcanic fields do not lie along a hot-spot trace, the rocks are compositionally similar to ocean island basalts. Although the rocks show some evidence for fractionation, the dominant control on composition is by varying degrees of partial melting of a mantle source. Trace-element and isotopic data further constrain the mantle source.