Grand Challenges, Leading Edge Ideas, and Frontiers in Tectonics K.V. Hodges School of Earth and Space Exploration Arizona State University

Roadmap National Research Council perspectives Perspectives of colleagues Getting to the heart of the matter Personal perspectives on teaching integrated materials in the 21st Century

The NROES Report Charged to “identify high-priority new and emerging research opportunities in the Earth sciences over the next decade” Charged “to suggest new ways that EAR can help train the next generation of Earth scientists, support young investigators, and increase the participation of underrepresented groups in the field”

NROES Focus Recommendations The Early Earth Thermo-Chemical Internal Dynamics and Volatile Distribution Faulting and Deformation Processes Interactions among Climate, Surface Processes, Tectonics, and Deep Earth Processes Co-evolution of Life, Environment, and Climate Coupled Hydrogeomorphic-Ecosystem Response to Natural and Anthropogenic Change Biogeochemical and Water Cycles in Terrestrial Environments and Impacts of Global Change Recent Advances in Geochronology

The Early Earth Many uniquely critical events occurred early in Earth’s history: delivery of the material that built Earth; formation of the Moon; and the differentiation events that formed the core and earliest crust, the oceans, and the atmosphere. Earth’s early history set the stage for its subsequent dynamic and geochemical evolution, from an environment dominated by impacts and magma oceans to the habitable environment dominated by the plate tectonics of today. How did plate tectonics arise on Earth? On what time frame did it happen? Why is Earth the only planet in the solar system that appears to have evolved to that point?

Thermo-Chemical Internal Dynamics and Volatile Distribution The huge dynamic circulation systems in Earth’s mantle and core circulate heat and materials, drive the long-term evolution of continents, generate the magnetic field, and cycle volatiles into and out of the interior, maintaining bulk chemistry of the oceans and atmosphere. Resolving the present-day configuration and processes of the mantle and core convective systems with high resolution is a key undertaking for developing models of the past and future evolution of the system, the thermal evolution of Earth, and the volatile flux in Earth. What are the relationships among planetary and lithospheric dynamics? How did the continents come to be?

Faulting and Deformation Processes Exciting discoveries, driven by increased instrumentation around fault zones, have been made regarding the spectrum of faulting processes and mechanisms. These present an opportunity to make significant progress on understanding faulting, related deformation processes, and resulting earthquake hazards. What are the relationships among fault zone dynamics and regional- or lithosphere- scale deformational processes?

Interactions among Climate, Surface Processes, Tectonics, and Deeper Earth Processes The broad interactions among climate, Earth surface processes, and tectonics are an area of compelling research opportunities that center on interactions among topography, hydrology and hydrogeology, physical and chemical denudation, sedimentary deposition, and deformation in tectonically active mountain belts. How do orogenic systems influence climate? How does climate influence orogenic systems? Can we disentangle the two?

Co-evolution of Life, Environment, and Climate The deep-time geological record has provided a compelling narrative of changes in Earth’s climate, environment, and evolving life, many of which provide analogs, insight, and context for understanding human’s place in the Earth system and current anthropogenic change. How does tectonics influence societal evolution?

Coupled Hydrogeomorphic-Ecosystem Response to Natural and Anthropogenic Change Understanding the response of large scale landscapes and ecosystems to disturbance and climate change requires greater mechanistic understanding of the interactions and feedbacks among hydrological drivers, landscape morphology, and biotic processes. If tectonics can influence climate and landscape physiography, in what ways does the evolution of orogenic systems influence ecosystem evolution?

Biogeochemical and Water Cycles in Terrestrial Environments and Impacts of Global Change Humans are altering the physical, chemical, and biological states of and feedbacks among essential components of Earth’s detailed surface system. At the same time, atmospheric temperature and carbon dioxide levels have increased and are impacting carbon storage in the terrestrial environment, the water cycle, and a range of intertwined biogeochemical cycles and atmospheric properties that feed back on climate and ecosystems. What does the coupling of climate and tectonics predict regarding the long-term influence of tectonic activity on the hydrosphere? How strong are the feedback loops between tectonics and geochemical and biogeochemical cycles? Is tectonics somehow different in the Anthropocene, or is that simply a breathtaking conceit?

Recent Advances in Geochronology The global span of the geosystems involved requires synoptic observations provided by global networks of geophysical, geochemical, petrological, and environmental facilities and data collection efforts. EAR should explore new mechanisms for geochronology laboratories that will service the geochronology requirements of the broad suite of research opportunities while sustaining technical advances in methodologies. What are the timescales over which different tectonic processes operate? What is the pace and tempo of tectonics? How are consistent are geodetic, neotectonic, and geologic constraints on the kinematics of deformation fields? How consistent are rates as measured on the millenial vs. million-year timescales?

Key Educational Concepts from the Community Physics rules! (Dynamics, mechanics [e.g., isostacy], rheology, strength) Value of multiple models (critical wedge, potential energy, viscous sheet) Limitations of models for more than understanding basic concepts (too much critical wedge can be a dangerous thing...) It all begins and ends with field observation The present is the key to the past (from plate tectonics to active continental tectonics) Exploit unusual ways to monitor deformation fields (e.g., seismic anisotropy, geodetically constrained crustal flow fields, seismicity maps) Exploit the linkage between tectonics and geomorphology Remember that decoupling within the lithosphere can confound strain field estimations Modern lithospheric structure represents only a moment in time

The Heart of It... Tectonics is the most fundamentally integrative “field” within the earth sciences. To do it well, you must be a polymath, with (at least) a firm grasp of the concepts and concept interactions of geochemistry, geomorphology, geophysics, and structural geology. Teaching tectonics should be as integrative as the field itself. Tectonics is the perfect capstone course for a modern earth science curriculum; it allows the instructor to reinforce nearly every other foundational subject

Transdisciplinary Teaching Less about facts and basic concepts (which can be acquired very effectively on line these days) and more about concept relationships A focus on cause, effect, and that nebulous region in between Emphasize the power of integration Emphasize the importance in science of multiple working hypotheses and the healthy debate that characterizes the best science Case studies are extremely well suited for this sort of application