WHOLE CRUST GEOPHYSICAL TRANSECT MODELS ACROSS THE SOUTH-CENTRAL MARGIN OF ALASKA

Integrated two-dimensional gravity and magnetic models along a series of margin-perpendicular transects serve to summarize existing data on the overall architecture of the crust and upper mantle along the south-central margin of Alaska. The transects encompass Cook Inlet and adjacent regions to the east and west. The Cook Inlet basin is a forearc basin above the southern Alaska subduction zone where the down-going Pacific plate plunges beneath the far-travelled Wrangellia and Penninsular terrains and the active Aleutian arc. Relevant available data for the cross-sections include earthquake solutions, deep seismic interpretation along the Trans-Alaska crustal transect, exploration drillhole and shallow seismic data in Cook Inlet, regional geologic mapping and cross-sections, limited seismic tomography, magnetotelluric data, and, of course, regional gravity and magnetic data compilations. Although some details of the models are only loosely constrained, these transect models represent a self-consistent framework for building a three-dimensional understanding of the complex margin. This geophysical framework provides important background for resource assessment studies including hydrocarbon assessment in Cook Inlet and mineral assessment in the Western Alaska Range and in southwest Alaska. Additionally, regional seismic hazard studies, including assessment of deep mega-thrust earthquakes as well as more shallow events, are dependent on a three-dimensional understanding of crustal structure.