Synthesis of the Seismic Structure of the Greater Alaska Region: Continental Lithosphere

Abstract

Significant advances have been made over the last two decades in constraining the structure of the continental lithosphere in Alaska, particularly with the EarthScope USArray seismic data collection efforts. This paper distills recent seismic models in Alaska and western Yukon (Canada) and relates them to major faults and tectonic terranes. We synthesize results from eight shear-wave velocity models and seven crustal thickness models. Through objective clustering of seismic velocity profiles, we identify six different velocity domains, separately for the crust (at the depth range of 10-50 km) and the mantle (at the depth range of 40-120 km). The crustal seismic domains show strong correlations with average crustal thickness patterns and the distribution of major faults and tectonic terranes. The mantle seismic velocity domains demonstrate signatures of major faults and tectonic terranes in northern Alaska while in southern Alaska the domains are primarily controlled by the geometry of the subducting lithosphere. The results of this study have significant implications for the tectonics and geodynamics of the overriding continental lithosphere from the margin to the interior. This synthesis will be of interest to future studies of Alaska as well as other modern and ancient systems involving convergent margins and terrane accretions.