CONNECTING MULTI-SCALE MANTLE CONVECTION, DEEP CONTINENTAL STRUCTURE, AND THE GEOLOGICAL EVOLUTION OF NORTH AMERICA WITH EARTHSCOPE SEISMOLOGY (Invited Presentation)

EarthScope seismic data illuminate heterogeneous crust and mantle properties beneath North America across an unprecedented range of spatial scales. Consequently, recent seismic analyses are providing novel insight into the lithospheric structure underlying diverse of geological provinces and the convective processes that govern the North American plate’s basal boundary conditions. Among the primary seismological tools are tomographic imaging of continuous 3D P and S velocities, converted wave imaging of sharp sub-horizontal interfaces, and detection of lateral and vertical variations in anisotropy of seismic velocities. Many seismic models are emerging from a broad range of research groups, many of whom are represented in this coauthor list. Given the fundamental advance in data coverage it is, perhaps, unsurprising that these models reveal many structures that are geologically intuitive, yet many others whose potential origins motivate vigorous debate and identify directions for further interdisciplinary investigation. The purpose of this multi-media presentation is to showcase examples of many of these structures, and to do so in a setting that encourages discussion and accessibility for a broad range of geologists. Topics of focus will include: 1) present day segmentation of subducted former oceanic lithosphere and its potential legacy in triggering geologic transitions such as the cessation of the Laramide orogeny and the initiation of the Yellowstone hotspot, 2) intense lateral heterogeneity at depths near the base of the lithosphere (about 50-200 km) and implications for long-term preservation and modification of continental mantle lithosphere, and 3) isotropic and anisotropic stratigraphy of tectonically active and stable continental lithosphere and their potential significance for partitioning of tectonic strain and chemical fluxes into the lithosphere. A unifying theme is that EarthScope-based seismology yields a rich variety of new seismic imagery, but accomplishing EarthScope’s goal of a 4D understanding of North America continues to require careful integration of geological and geophysical constraints and increasingly interdisciplinary hypothesis testing.