Peter van Keken (Carnegie Institution for Science)
Large amounts of water enter the Earth at subduction zones. As the lithosphere descends and warm metamorphic dehydration reactions release fluids that trigger arc volcanism and can aid intermediate-depth seismicity. Thermal models provide a complementary view to observational and experimental work. In this talk I will discuss how finite element models of subduction zones allow for the prediction of the thermal structure and evolution of subduction zones; how these predictions compare to independent geophysical and geochemical observations; and how these prediction are used in complementary geophysical and geochemical modeling.
About the Speaker
Peter van Keken studies the dynamics that underlie plate tectonics. The tectonic evolution of the Earth is driven by the slow release of heat from the Earth's interior that is conducted and advected by the slow solid-state deformation of the Earth's mantle. The melting at mid-oceanic ridges and subsequent recycling of the oceanic lithosphere at subduction zones imparts unique chemical characteristics, which over the long term cause a profound chemical evolution of the Earth's mantle as is seen in mid-oceanic ridge and hotspot lavas.
Van Keken develops computational models that use finite element techniques to solve the governing equations for slow convection in the silicate Earth. These models use constraints from mineral physics and petrology and are tested using constraints from geodynamics (such as plate velocities and surface heatflow), seismology (tomography, receiver functions, phase conversions), geochemistry (radiogenic isotope constraints on mantle composition) and petrology (mineral stability under high pressure and temperature). Significant work is performed in collaborative and interdisciplinary projects with researchers in the United States (the University of Michigan, Cornell, UC Santa Barbara, Columbia University) and abroad (Tohoku University, Oxford, Imperial, ETH Zürich).
His research has focused in recent years on the use of constraints from geochemistry in testing long-term evolution models of the Earth's mantle (Brandenburg et al., 2008; van Keken, 2013), the dynamics and seismic discoverability of mantle plumes (Hwang et al., 2011; Styles et al., 2011; Bossmann and van Keken, 2013) and the thermal structure and dynamics of subduction zones (e.g., van Keken et al., 2003; Syracuse et al., 2010; Wilson et al., 2014) with a specific focus on the role of volatiles (van Keken et al., 2011), arc magmatism (Kimura et al., 2010; 2014; Turner et al., 2012) and the nature of intermediate-depth seismicity (van Keken et al., 2012; Barcheck et al., 2012; Abers et al., 2013).
As part of his specialization in computational geodynamics van Keken develops community benchmarks (e.g., van Keken et al., 1997; 2010; King et al., 2010), develops high-resolution 3D models of subduction (Kneller and van Keken, 2007; Bengtson and van Keken, 2012; Morishige and van Keken, 2014) and tests numerical models against laboratory experiments (van Keken, 1997; Vatteville et al., 2009; van Keken et al., 2013). He has contributed to reviews on mantle convection and its role in the geochemical evolution of the Earth (van Keken et al., 2002; 2004; van Keken, 2013), the dynamics of subduction zones (van Keken, 2003) and the nature of hot spot volcanism (Ito and van Keken, 2007; Ballmer et al., 2015).
About this Series
Weekly talks given by leading thinkers in the areas of geology, geophysics, geobiology, geochemistry, atmospheric science, oceanography, climatology, and planetary science. Lectures take place on Wednesdays from 3:45pm in MIT Building 54 room 915, unless otherwise noted.