EXPLORING THE HYPOTHESIS OF THE NORTH PACIFIC RIM OROGENIC STREAM (NPRS) AND THE WESTWARD TECTONIC ESCAPE OF ALASKAN CRUST

The north Pacific rim is a ~600-800 km-wide, tectonically active plate boundary zone that is a belt of laterally mobilized crust that characterize a moving "orogenic stream"--the north Pacific rim orogenic stream (NPRS). Within the NPRS crustal blocks, or terranes, are being transported along a counterclockwise trajectory following the slip-lines of a family of continental-scale strike-slip faults (i.e., Tintina, Denali, Kobuk, Kaltag, Bruin Bay, Border Ranges, etc) that track northwest from western Canada through the curving "oroclinal" bend or nexus of central Alaska and southwest toward the Aleutian subduction zone. Throughout the Cenozoic (and most likely earlier), at and west of the curvature of the Alaskan nexus the NPRS has been, in a fashion analogous to Anatolia, undergoing westward tectonic escape (extrusion). During lateral transport relatively rigid crustal blocks acquired counterclockwise paleomagnetic rotations and fault-juxtaposed boundaries while moving differentially within the NPRS from their original point of entrainment toward a free tectonic face provided by the subduction zone system of the Aleutian-Bering Sea region. In the early and middle Tertiary, the free-face system included the now-abandoned subduction zones of the Beringian margin connecting Alaska and NE Russia and, offshore and within the deep water Bering Sea Basin, those of Shirshov and Bowers Ridges (arcs). The NPRS model encompasses terrane tectonics and provides a dynamic framework of lateral crustal motion to view and track the plate-boundary driven, mobilistic nature of the Pacific's northern continental rim moving toward its outletting system of subduction zones