Displacement History of the Chugach-Prince William Terrane

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A strong discordance exists between displacement estimates for Cordilleran tectonic terranes inferred from paleomagnetic studies as opposed to geologic studies. Existing paleomagnetic data from southern Alaska suggest large northward displacements of the Chugach-Prince William (CPW) terrane with respect to the southern Alaska terrane since the lower Tertiary, but geologic evidence suggests the two terranes were juxtaposed in early Tertiary time. However, the paleomagnetic data base for the CPW terrane is small and highly variable and may therefore be unreliable. This study will resolve the discrepancy by detailed paleomagnetic analysis of a suite of ophiolitic and dike rocks already obtained from the Kenai Peninsula and Knight-Island. The results will clarify the tectonic evolution of the northern Cordillera, particularly the Alaskan segment, and will have bearing on orogen-parallel displacement estimates for accreted terranes in other orogenic belts.