HOTSPOT MOTION, FRAMES OF REFERENCE, AND PREDICTED DRIVING FORCES FOR NORTH AMERICAN TECTONOSTRATIGRAPHIC TERRANES

The motion of oceanic plates in the paleo-Pacific basin clearly provides a driving force for the translation of North American tectonostratigraphic terranes. But the history of Pacific basin plate motion has typically relied on a fixed-hotspot reference frame. The Hawaiian-Emperor hotspot track has played a prominent role in defining the fixed hotspot concept. However, paleomagnetic and radiometric-age data resulting from Ocean Drilling Program Leg 197 define an age-progressive paleolatitude history indicating that the Emperor Seamount trend was principally formed by rapid (> 40 mm/yr) southward drift of the Hawaiian hotspot during Late Cretaceous to Early Tertiary times (81-47 Ma). This motion is consistent with results from the analyses of plate circuits, shallow and deep-water sediment facies and geodynamic modeling. Together, these approaches highlight the conclusion that hotspot tracks can reflect mantle flow as well as plate motion. Accordingly, we investigate alternative means of reconstructing Pacific basin oceanic plate motion relative to North America; we will present consistency tests of the results. Finally we will discuss two categories of revisions highlighted by the recognition of hotspot motion: i. Changes in the oceanic plate that could feasibly interact with North America over a given time interval and ii. Changes in the azimuth and rate of plate convergence and associated components of coast-wise translation for tectonostratigraphic terranes.