Abstract
This dissertation presents new methods of visualizing, teaching, assessing, modeling, and understanding tectonics on Earth and other celestial bodies. Tectonics is the study of planetary lithospheres and includes impact, plate, plume, cryo- and gravitational mechanisms. This dissertation is concerned with plate tectonics and plate/mantle plume interactions. Plate tectonics describes the mainly horizontal motion of lithospheric plates over the asthenosphere. Lithosphere is created at ridges and consumed at subduction zones. In addition to the plate tectonic system, mantle plumes also contribute to mass motions in the subsurface Earth. Both plate tectonics and plume upwelling processes help shape the present form of the planetary surface, including long volcanic island chains, deep ocean basins, and plate boundary triple junctions. Better understanding of these processes by visualization and numerical modeling is one of the primary goals of this study. In the geospatial analysis lab at ODU, our research methodology starts with the creation of visualizations for teaching. These include Google Earth-based virtual field explorations enhanced with digitized specimens and emergent geological and geophysical cross sections. We test these in classes with IRB compliance and sometimes this leads to the discovery of tectonic research questions which we then explore. Settings studied in this investigation are Tonga Trench in the western Pacific Ocean, Artemis on Venus, the Hawaiian-Emperor seamount chain, and the Azores triple junction. Some of these cases pose specific geophysical problems that were selected for further study. The Tonga Trench is a subduction zone that includes trench rollback and opening of a marginal basin—the Lau Basin. The rollback process is difficult to imagine, and therefore we created a set of instructional resources using COLLADA models and the Google Earth Application Programming Interface (API). Animated models for the assessments tests and exploration of different initiations of the subduction process led to a new alternative hypothesis for rollback. Virtual field explorations required the development of new interface features for the Google Earth API. All these instructional materials were combined into modular multi-user virtual field trip experiences and were subject to IRB-compliant evaluation of learning outcomes. Animated COLLADA models for the Hawaii Islands and Emperor Seamounts helped explain the origin and time progression of the island chain. From seismic data, a three-dimensional reconstruction of the Hawaiian mantle plume was created raising the question of the horizontal advection of the plume conduit in the mantle and its correlation with the change in trend of the islands. The Hawaiian–Emperor chain on Earth is spread out as the Pacific plate is moving over the Hawaiian mantle plume. On Venus, however, the Artemis structure was able to grow to super-plume size due to the absence of plate motion. For Venus, visualization was done on a much larger scale,…
Published Version
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