Clint Conrad

Professor of Mantle Dynamics


Office: ZEB-bygget 2.328
E-mail: c.p.conrad@geo.uio.no


Centre for Earth Evolution and Dynamics (CEED)
Department of Geosciences
University of Oslo
Postboks 1028 Blindern
N-0315 Oslo
Norway


Main | Background | Projects & Models | Research Areas | Publications | Group | Courses


Geodynamics Research Areas

My research group has worked in several different subfields of geodynamics, investigating a variety different geophysical processes. Broadly characterized, we have contributed to the research areas listed below. Follow the links for more details, and for relevant papers on these topics.


Sea Level and the Solid Earth


Sea level change represents a fundamental boundary on the Earth's surface. Changes to sea level are one of the more dramatic consequences of modern-day climate change, and can be observed in the geologic record as periodic transgressions and regressions of continental boundaries. The solid earth influences sea level on timescales ranging from decades to billions of years. Generally, three types of solid earth deformation affect influence sea level. I describe these below, and in this review publication:
  1. Conrad, C.P. (2013), The solid earth's influence on sea level, Geological Society of America Bulletin, 125, 1027-1052, doi:10.1130/B30764.1. [online version] [reprint] [cover image]

Elastic Deformation: Important for Modern Sea Level Change


Sea Level and the Solid Earth: Elastic Deformation On the shortest timescales, redistributions of water loads on the Earth's surface (e.g., glacial melting) cause elastic deformation of the Earth, which affects sea level. This mechanism causes sea level to rise more slowly in regions close to rapid mass loss, and faster away from them. Future climate change-induced sea level rise will be dramatically influenced by this type of solid earth deformation.
  1. Dangendorf, S., M. Marcos, G. Wöppelmann, C.P. Conrad, T. Frederikse, and R. Riva (2017), Reassessment of 20th century global mean sea level rise, Proceedings of the National Academy of Sciences, 114, 5946-5951, doi: 10.1073/pnas.161007114. [online version] [reprint] [supporting information]
  2. Veit, E., and C.P. Conrad (2016), The impact of groundwater depletion on spatial variations in sea level change during the past century, Geophysical Research Letters, 43, 3351-3359, doi:10.1029/2012GL068118. [online version] [reprint] [sea level response model]
  3. Fiedler§, J.W., and C.P. Conrad (2010), Spatial variability of sea level rise due to water impoundment behind dams, Geophysical Research Letters, 37, L12603, doi:10.1029/2010GL043462. [online version] [reprint] [highlight in Nature] [response model]
  4. Conrad, C.P., and B.H. Hager (1997), Spatial variations in the rate of sea level rise caused by the present-day melting of glaciers and ice sheets, Geophysical Research Letters, 24, 1503-1506, doi:10.1029/97GL01338. [online version] [reprint]
  5. Conrad, C.P., and B.H. Hager (1995), The elastic response of the earth to interannual variations in Antarctic precipitation, Geophysical Research Letters, 22, 3183-3186, doi:10.1029/95GL03176. [online version] [reprint]

Viscous Deformation: Glacial Isostatic Adjustment (GIA)


Sea Level and the Solid Earth: Postglacial Deformation On timescales of thousands to hundreds of thousands of years, the solid earth responds to surface loading by slow deformation as the mantle viscously deforms. This deformation can produce dramatic changes in sea level as both the land surface and the sea surface deform. Indeed, the land and sea surfaces are still adjusting to deglaciation that ended the last ice age.
  1. Hartmann, R., J. Ebbing, and C.P. Conrad (2020), A Multiple 1D Earth Approach (M1DEA) to account for lateral viscosity variations in solutions of the sea level equation: An application for glacial isostatic adjustment by Antarctic deglaciation, Journal of Geodynamics, 135, 101695, doi:10.1016/j.jog.2020.101695. [online version] [reprint] [GitHub: Rotational Feedback for Selen]

Geological Deformation: Sea Level Through Earth History


Sea Level and the Solid Earth: Geological Deformation On timescales longer than millions of years, geological deformations largely control sea level change. These mostly occur via mechanisms that change the volume of the ocean basins, such as changes in seafloor spreading, sedimentation cover, seafloor volcanism, dynamic deflection of the seafloor, and net contraction or expansion of continental area. Seawater may also be lost to the mantle interior via subduction, or outgassed by volcanism, and imbalances between these processes can lead to sea level change.
  1. Karlsen, K.S., M. Domeier, C. Gaina, and C.P. Conrad (2020), A tracer-based algorithm for automatic generation of seafloor age grids from plate tectonic reconstructions, Computers and Geosciences, 140, 104508, doi:10.1016/j.cageo.2020.104508. [online version] [preprint] [supplemental material] [TracTec code]
  2. Sames, B., M. Wagreich, C.P. Conrad, and S. Iqbal (2020) Aquifer-eustasy as the main driver of short-term sea-level fluctuations during Cretaceous hothouse climate phases, Geological Society, London, Special Publications, 498, 9-38, doi:10.1144/SP498-2019-105. [online version] [reprint]
  3. Karlsen, K.S., C.P. Conrad, and V. Magni (2019), Deep water cycling and sea level change since the breakup of Pangea, Geochemistry, Geophysics, Geosystems, 20, 2919-2935, doi:10.1029/2019GC008232. [online version] [reprint]
  4. Plyusnina, E.E., D.A. Ruban, C.P. Conrad, G.d.S. dos Anjos Zerfass, and H. Zerfass (2016), Long-term eustatic cyclicity in the Paleogene: a critical assessment, Proceedings of the Geologists' Association, 127, 425-434, doi: 10.1016/j.pgeola.2016.03.006. [online version] [reprint]
  5. Sames, B., M. Wagreich, J.E. Wendler, B.U. Haq, C.P. Conrad, M.C. Melinte-Dobrinescu, X. Hu, I. Wendler, E. Wolfgring, I.Ö. Yilmaz, and S.O. Zorina (2016), Review: Short-term sea-level changes in a greenhouse world - a view from the Cretaceous, Palaeogeography, Palaeoclimatology, Palaeoecology, 441, Part 3, 393-411, doi:10.1016/j.palaeo.2015.10.045. [online version] [Cretaceous Sea Level Volume] [reprint]
  6. Ruban, D.A., and C.P. Conrad (2013), Late Silurian-Middle Devonian long-term shoreline shifts on the northern Gondwanan margin: Eustatic versus tectonic controls, Proceedings of the Geologists' Association, 124, 883-892, doi:10.1016/j.pgeola.2012.12.004. [online version] [reprint]
  7. Ruban, D.A., S.O. Zorina, C.P. Conrad, and N.I. Afanasieva (2012), In quest of Paleocene global-scale transgressions and regressions: constraints from a synthesis of regional trends, Proceedings of the Geologists' Association, 123, 7-18, doi:10.1016/j.pgeola.2011.08.003. [online version] [reprint]
  8. Ruban, D., C.P. Conrad, and A.J. van Loon (2010), The challenge of reconstructing the Phanerozoic sea level and the Pacific Basin tectonics, Geologos, 16, 237-245, doi:10.2478/v10118-010-0007-9. [online version] [reprint]
  9. Ruban, D., S. Zorina, and C.P. Conrad (2010), No global-scale transgressive-regressive cycles in the Thanetian (Paleocene): evidence from interregional correlation, Palaeogeography Palaeoclimatology Palaeoecology, 295, 226-235, doi:10.1016/j.palaeo.2010.05.040. [online version] [reprint]
  10. Conrad, C.P., and L. Husson (2009), Influence of dynamic topography on sea level and its rate of change, Lithosphere, 1, 110-120, doi:10.1130/L32.1. [online version] [reprint] [dynamic topography model]
  11. Husson, L., and C.P. Conrad (2006), Tectonic velocities, dynamic topography, and relative sea level, Geophysical Research Letters, 33, L18303, doi:10.1029/2006GL026834. [online version] [reprint]
  12. Xu, X., C. Lithgow-Bertelloni, and C.P. Conrad (2006), Global reconstructions of Cenozoic seafloor ages: Implications for bathymetry and sea level, Earth and Planetary Science Letters, 243, 552-564, doi:10.1016/j.epsl.2006.01.010. [online version] [reprint]

Observations of Global Mantle Flow

Global Mantle Flow Viscous flow within the Earth's mantle ultimately drives plate tectonics and most of the time-dependent geological deformation that we observe at the Earth's surface. Seismic constraints on mantle structure, coupled with improved computational abilities, have allowed us to constrain patterns of flow presently occurring in the Earth's mantle. My research group has been constraining such models of global mantle flow using various geological and geophysical observations. This effort has led to a greater understanding of how surface tectonic and mantle dynamics interact to drive geological deformation and modulate mantle convection.

Global Tectonics and Mantle Flow

The tectonic plates are part of the mantle, and their motions represent the surface expression of the mantle deformation occurring beneath them. We have explored the link between plate motions and mantle flow in a variety of ways.
  1. Crameri, F., C.P. Conrad, L. Montési, and C.R. Lithgow-Bertelloni (2019) The dynamic life of an oceanic plate, Tectonophysics, 760, 107-135, doi:10.1016/j.tecto.2018.03.016. [online version] [reprint] [Torsvik Special Issue]
  2. Becker, T.W., A.J. Schaeffer, S. Lebedev, and C.P. Conrad (2015), Toward a generalized plate motion reference frame, Geophysical Research Letters, 42, 3188-3196, doi:10.1002/2015GL063695. [online version] [reprint] [supplementary material]
  3. Conrad, C.P., B. Steinberger, and T.H. Torsvik (2013), Stability of active mantle upwelling revealed by net characteristics of plate tectonics, Nature, 498, 479-482, doi:10.1038/nature12203. [online version] [reprint] [online supplement] [auxiliary material]
    [Comment and Reply, reprint ]
  4. Combes, M., C. Grigné, L. Husson, C.P. Conrad, S. Le Yaouanq, M. Parentho├źn, C. Tisseau, and J. Tisseau (2012), Multiagent simulation of evolutive plate tectonics applied to the thermal evolution of the Earth, Geochemistry, Geophysics, Geosystems, 13, Q05006, doi:10.1029/2011GC004014. [online version] [reprint]
  5. van Summeren, J., C.P. Conrad, and C. Lithgow-Bertelloni (2012), The importance of slab pull and a global asthenosphere to plate motions, Geochemistry, Geophysics, Geosystems, 13, Q0AK03, doi:10.1029/2011GC003873. [online version] [reprint] [theme issue]
  6. Steiner, S.A., and C.P. Conrad (2007), Does active mantle upwelling help drive plate motions?, Physics of the Earth and Planetary Interiors, 161, 103-114, doi:10.1016/j.pepi.2007.01.005. [online version] [reprint]

Dynamic Topography Global Mantle Flow

Stresses from mantle flow can cause uplift or subsidence at the Earth's surface. In a continental region, dynamic topography can cause regional transgression or regression events as as the land surface moves relative to sea level. If an oceanic region, dynamic topography changes the volume of the ocean basins, and can cause eustatic sea level change. Observations of uplift and subsidence are prevalent in the geologic record, and therefore useful for constraining past dynamic topography.
  1. Steinberger, B., C.P. Conrad, A. Osei Tutu, and M.J. Hoggard (2019) On the amplitude of dynamic topography at spherical harmonic degree two, Tectonophysics, 760, 221-228, doi:10.1016/j.tecto.2017.11.032. [online version] [reprint] [Torsvik Special Issue]
  2. Watkins, C.E., and C.P. Conrad (2018), Constraints on dynamic topography from asymmetric subsidence of the mid-ocean ridges, Earth and Planetary Science Letters, 484, 264-275, doi:10.1016/j.epsl.2017.12.028. [online version] [reprint]
  3. Conrad, C.P., and L. Husson (2009), Influence of dynamic topography on sea level and its rate of change, Lithosphere, 1, 110-120, doi:10.1130/L32.1. [online version] [reprint] [dynamic topography model]
  4. Husson, L., and C.P. Conrad (2006), Tectonic velocities, dynamic topography, and relative sea level, Geophysical Research Letters, 33, L18303, doi:10.1029/2006GL026834. [online version] [reprint]
  5. Conrad, C.P., C. Lithgow-Bertelloni, and K.E. Louden (2004), Iceland, the Farallon slab, and dynamic topography of the North Atlantic, Geology, 32, 177-180, doi:10.1130/G20137.1 [online version] [reprint]
  6. Conrad, C.P., and M. Gurnis (2003), Mantle flow, seismic tomography and the breakup of Gondwanaland: Integrating mantle convection backwards in time, Geochemistry, Geophysics, Geosystems, 4, 1031, doi:10.1029/2001GC000299. [online version] [reprint]

Anisotropy and Asthenosphere Deformation

When subjected to shearing deformation, olivine grains in the Earth's upper mantle acquire a texture that can be detected using seismic observations. This texture is called seismic anisotropy, and it can be used to constrain the pattern of mantle deformation that produced it. The texture may also be viscously anisotropic, which can affect deformation. We have developed models of mantle flow that we have been able to link directly to observations of seismic anisotropy.
  1. Hansen, L.N., C.P. Conrad, Y. Boneh, P. Skemer, J.M. Warren, and D.L. Kohlstedt (2016), Viscous anisotropy of textured olivine aggregates, Part 2: Micromechanical model, Journal of Geophysical Research, 121, 7137-7160, doi: 10.1002/2016JB013240. [online version] [reprint] [auxiliary material]
  2. Becker, T.W., C.P. Conrad, A.J. Schaeffer, and S. Lebedev (2014), Origin of azimuthal seismic anisotropy in ocean plates and mantle, Earth and Planetary Science Letters, 401, 236-250, doi:10.1016/j.epsl.2014.06.014. [online version] [reprint] [supplementary material]
  3. Natarov, S.I., and C.P. Conrad (2012), The role of Poiseuille flow in creating depth-variation of asthenospheric shear, Geophysical Journal International, 190 , 1297-1310, doi:10.1111/j.1365-246X.2012.05562.x. [online version] [reprint]
  4. Conrad, C.P., and M.D. Behn (2010), Constraints on lithosphere net rotation and asthenospheric viscosity from global mantle flow models and seismic anisotropy, Geochemistry, Geophysics, Geosystems, 11, Q05W05, doi:10.1029/2009GC002970. [online version] [reprint] [theme issue] [mantle flow model]
  5. Conrad, C.P., M.D. Behn, and P.G. Silver (2007), Global mantle flow and the development of seismic anisotropy: Differences between the oceanic and continental upper mantle, Journal of Geophysical Research, 112, B07317, doi:10.1029/2006JB004608. [online version] [reprint] [auxiliary material] [flow model and anisotropy code]
  6. Behn, M.D., C.P. Conrad, and P.G. Silver (2004), Detection of upper mantle flow associated with the African superplume, Earth and Planetary Science Letters, 224, 259-274, doi:10.1016/j.epsl.2004.05.026. [online version] [reprint]

Mantle Structures: Plumes, LLSVPs, and the CMB

The mantle features exotic structures such as the Large Low Seismic Velocity Provinces (LLSVPs) at the base of the mantle and mantle plumes that are thought to arise from the lowermost mantle. These structures interact with the overall flow occurring within the mantle We have been able to link the dynamics of parts of the mantle interior to the overall dynamics of the rest of the mantle.
  1. Heyn, B.H., C.P. Conrad, and R.G. Trønnes (2018), How thermochemical piles can (periodically) generate plumes at their edges, Journal of Geophysical Research, 125, e2019JB018726, doi:10.1029/2019JB018726. [online version] [preprint]
  2. Heyn, B.H., C.P. Conrad, and R.G. Trønnes (2018), Stabilizing effect of compositional viscosity contrasts on thermochemical piles, Geophysical Research Letters, 45, 7523-7532, doi:10.1029/2018GL078799. [online version] [reprint] [supplemental information]
  3. Husson, L., and C.P. Conrad (2012), On the location of hotspots in the framework of mantle convection, Geophysical Research Letters, 39, L17304, doi:10.1029/2012GL052866. [online version] [reprint] [table]
  4. Métivier, L., and C.P. Conrad (2008), Body tides of a convecting, laterally heterogeneous, and aspherical Earth, Journal of Geophysical Research, 113, B11405, doi:10.1029/2007JB005448. [online version] [reprint] [auxiliary material]

Intraplate Volcanism and the Shear-Driven Upwelling


Several mechanisms have been proposed to explain volcanism occurring away from tectonic plate boundaries. Although mantle plumes may produce most of the high-volume intraplate volcanism (e.g., Hawaii), low-volume examples likely require alternative explanations. We have proposed new volcanic processes that may help to explain seamounts and small-scale basaltic volcanism on land.

The Shear-Driven Upwelling

The Shear-Driven Upwelling We have proposed a new mechanism: The "shear-driven upwelling" (SDU), in which mantle upwelling is driven by the action of asthenospheric shear on viscosity heterogeneity (either "topography" on the base of the lithosphere, or a low-viscosity "pocket" embedded within the asthenosphere). The energy for this upwelling arises from global mantle flow (which induces asthenospheric shear), rather than local density heterogeneity. We have shown that SDU can drive upwelling sufficient to induce low-volume basaltic volcanism with a surface expression that is distinct from that produced by hotspots. We have also shown that regions of the asthenosphere that are shearing rapidly also tend to have higher rates of intraplate volcanism.
  1. Bianco, T.A., C.P. Conrad, and E.I. Smith (2011), Time-dependence of intraplate volcanism caused by shear-driven upwelling of low-viscosity regions within the asthenosphere, Journal of Geophysical Research, 116, B11103, doi:10.1029/2011JB008270. [online version] [reprint]
  2. Conrad, C.P., T.A. Bianco, E.I. Smith, and P. Wessel (2011), Patterns of intraplate volcanism controlled by asthenospheric shear, Nature Geoscience, 4, 317-321, doi:10.1038/ngeo1111. [online version] [reprint] [online supplement] [news & views] [Basaltic volcanism locations: intraplate other]
  3. Conrad, C.P., B. Wu, E.I. Smith, T.A. Bianco, and A. Tibbetts (2010), Shear-driven upwelling induced by lateral viscosity variations and asthenospheric shear: A mechanism for intraplate volcanism, Physics of the Earth and Planetary Interiors, 178, 162-175, doi:10.1016/j.pepi.2009.10.001. [online version] [reprint] [highlight in Nature Geoscience] [summary on MantlePlumes.org]

Seamount Volcanism

Seamounts Seamounts are small mountains below the sea surface that usually are volcanic in nature. Each represents a volcanic event that occurred at some time in history of the seafloor, but the timing and mechanism for this event is usually unknown. By looking for patterns in seamount volumes and locations, we can infer something about the geophysical processes that produce them.
  1. Conrad, C.P., K. Selway, M.M. Hirschmann, M.D. Ballmer, and P. Wessel (2017), Constraints on volumes and patterns of asthenospheric melt from the space-time distribution of seamounts, Geophysical Research Letters, 44, 7203-7210, doi:10.1002/2017GL074098. [online version] [reprint]
  2. Ballmer, M.D., C.P. Conrad, E.I. Smith, and N. Harmon (2013), Non-hotspot volcano chains produced by migration of shear-driven upwelling toward the East Pacific Rise, Geology, 41, 479-482, doi:10.1130/G33804.1. [online version] [reprint] [auxiliary material]

Continental Basaltic Volcanism

Small-scale volcanism also occurs in many continental environments, and is easier to study compared to submerged seamounts. Some of the same processes that are important for seamounts are also important in continental environments.
  1. Ballmer, M.D., C.P. Conrad, E.I. Smith, and R. Johnsen (2015), Intraplate volcanism at the edges of the Colorado Plateau sustained by a combination of triggered edge-driven convection and shear-driven upwelling, Geochemistry, Geophysics, Geosystems, 16, 366-379, doi:10.1002/2014GC005641. [online version] [reprint] [auxiliary material]
  2. Smith, E.I., C.P. Conrad, T. Plank, A. Tibbetts, and D. Keenan (2008), Testing models for basaltic volcanism: implications for Yucca Mountain, Nevada, American Nuclear Society, Proceedings of the 12th International High-Level Radioactive Waste Management Conference, 157-164. [printed version] [reprint]

Dynamics and Tectonics of Earth's Lithosphere


Dynamics and Tectonics of Earth's Lithosphere Earth's lithosphere moves and deforms in response to the stresses exerted on it by topographic loads, tectonic forces, and viscous coupling to convective processes occurring in the underlying mantle. The dynamics of the lithosphere in turn influence mantle heat flow, plate motions, and a variety of tectonic processes such as mountain building. Our work has examined the interaction between lithospheric tectonics and mantle dynamics, and has constrained this interaction using a variety of geological and geophysical observations.

Seafloor Tectonics

The oceanic plates are the primary structure for transferring heat from Earth's interior to to the surface. We have used observations and models of the oceanic lithosphere to make inferrnces about the dynamics of the underlying mantle.
  1. Karlsen, K.S., M. Domeier, C. Gaina, and C.P. Conrad (2020), A tracer-based algorithm for automatic generation of seafloor age grids from plate tectonic reconstructions, Computers and Geosciences, 140, 104508, doi:10.1016/j.cageo.2020.104508. [online version] [preprint] [supplemental material] [TracTec code]
  2. Wessel, P., and C.P. Conrad (2019) Assessing models for Pacific absolute plate and plume motions, Geochemistry, Geophysics, Geosystems, 20, 6016-6032, doi:10.1029/2019GC008647. [online version] [preprint]
  3. Torsvik, T.H., B. Steinberger, G.E. Shephard, P.V. Doubrovine, C. Gaina, M Domeier, C.P. Conrad, and W.W. Sager (2019) Pacific-Panthalassic reconstructions: Overview, errata and the way forward, Geochemistry, Geophysics, Geosystems, 20, 3659-3689, doi:10.1029/2019GC008402. [online version] [reprint]
    Supplemental Files: [PACIFIC.ZIP] [Pacific_EARTHBYTE_Model_R.ZIP]
  4. Becker, T.W., C.P. Conrad, B. Buffett, and R.D. Müller (2009), Past and present seafloor age distributions and the temporal evolution of plate tectonic heat transport, Earth and Planetary Science Letters, 278, 233-242, doi:10.1016/j.epsl.2008.12.007. [online version] [reprint]
  5. Loyd, S.J., T.W. Becker, C.P. Conrad, C. Lithgow-Bertelloni, and F.A. Corsetti (2007), Time variability in Cenozoic reconstructions of mantle heat flow: Plate tectonic cycles and implications for Earth's thermal evolution, Proceedings of the National Academy of Sciences, 104, 14266-14271, doi:10.1073/pnas.0706667104. [online version] [reprint]
  6. Conrad, C.P., and C. Lithgow-Bertelloni (2007), Faster seafloor spreading and lithosphere production during the mid-Cenozoic, Geology, 35, 29-32, doi:10.1130/G22759A.1. [online version] [reprint]
  7. Xu, X., C. Lithgow-Bertelloni, and C.P. Conrad (2006), Global reconstructions of Cenozoic seafloor ages: Implications for bathymetry and sea level, Earth and Planetary Science Letters, 243, 552-564, doi:10.1016/j.epsl.2006.01.010. [online version] [reprint]

Continental Roots

The continents are thought to have "roots" that protrude deeply into the mantle interior. They are therefore likely to be more well-coupled to underlying mantle dynamics than the surrounding plates, which has implications for lithospheric stresses, plate motions, and cratonic stability.
  1. Paul, J., A. Ghosh, and C.P. Conrad (2019) Traction and strain-rate at the base of the lithosphere: An insight into cratonic survival, Geophysical Journal International, 217, 1024-1033, doi:10.1093/gji/ggz079. [online version] [reprint] [erratum] [supplemental material]
  2. Naliboff, J.B., C.P. Conrad, and C. Lithgow-Bertelloni (2009), Modification of the Lithospheric Stress Field by Lateral Variations in Plate-Mantle Coupling, Geophysical Research Letters, 36, L22307, doi:10.1029/2009GL040484. [online version] [reprint]
  3. Cooper, C.M., and C.P. Conrad (2009), Does the mantle control the maximum thickness of cratons?, Lithosphere, 1, 67-72, doi:10.1130/L40.1. [online version] [erratum] [reprint]
  4. Conrad, C.P., and C. Lithgow-Bertelloni (2006), Influence of continental roots and asthenosphere on plate-mantle coupling, Geophysical Research Letters, 33, L05312, doi:10.1029/2005GL025621. [online version] [reprint] [lithosphere thickness model]

Mountain Building

Mountain ranges form in response to teconic stresses, which ultimately are the result of mantle dynamics. We have linked mountain building events to underlying patterns of mantle flow.

  1. Faccenna, C., T.W. Becker, C.P. Conrad, and L. Husson (2013), Mountain building and mantle dynamics, Tectonics, 32, 80-93, doi:10.1029/2012TC003176. [online version] [reprint]
  2. Husson, L., C.P. Conrad, and C. Faccenna (2012), Plate motions, Andean orogeny, and volcanism above the South Atlantic convection cell, Earth and Planetary Science Letters, 317-318, 126-135, doi:10.1016/j.epsl.2011.11.040. [online version] [reprint]
  3. Meade, B.J., and C.P. Conrad (2008), Andean growth and the deceleration of South American subduction: Time evolution of a coupled orogen-subduction system, Earth and Planetary Science Letters, 275, 93-101, doi:10.1016/j.epsl.2008.08.007. [online version] [reprint]
  4. Husson, L., C.P. Conrad, and C. Faccenna (2008), Tethyan closure, Andean orogeny, and westward drift of the Pacific basin, Earth and Planetary Science Letters, 271, 303-310, doi:10.1016/j.epsl.2008.04.022. [online version] [reprint]

Exoplanets


ExoplanetsRecent astronomical observations have detected planets orbiting stars outside of our solar system. Many of these planets have sizes, densities, compositions, and temperatures that distinguish them from any known bodies in our own solar system. Thus, these "exoplanets" are likely to host planetary processes that have never been previously considered. Our work has contributed to undestanding how convection within exoplanet mantles may affect plate tectonics, geodynamos, and volcanism on these planets.
  1. van Summeren, J., E. Gaidos, and C.P. Conrad (2013), Magnetodynamo lifetimes for rocky, Earth-mass exoplanets with contrasting mantle convection regimes, Journal of Geophysical Research: Planets, 118, 938-951, doi:10.1002/jgre.20077. [online version] [reprint]
  2. van Summeren, J., C.P. Conrad, and E. Gaidos (2011), Mantle convection, plate tectonics, and volcanism on hot exo-Earths, The Astrophysical Journal Letters, 736, L15, doi:10.1088/2041-8205/736/1/L15. [online version] [reprint]
  3. Gaidos, E., C.P. Conrad, M. Manga, and J. Hernlund (2010), Thermodynamic limits on magnetodynamos in rocky exoplanets, Astrophysical Journal, 718, 596-609, doi:10.1088/0004-637X/718/2/596. [online version] [reprint]

Subduction Dynamics


Plate Tectonics and SubductionPlate subduction is one of the key processes that facilitates plate tectonics on Earth. By linking models of subduction to numerical models of plate motions and mantle flow, we have developed new constraints on the interaction between plate motions and subduction. In particular, we have shown that subducting slabs provide the largest driving force for plate tectonics, and couple to plate motions both directly (via guiding stresses transmitted within the slab) and indirectly (by inducing mantle flow that pushes on the base of plates).
  1. Wu, B., C.P. Conrad, and A. Heuret, C. Lithgow-Bertelloni, and S. Lallemand (2008), Reconciling strong slab pull and weak plate bending: The plate motion constraint on the strength of mantle slabs, Earth and Planetary Science Letters, 272, 412-421, doi:10.1016/j.epsl.2008.05.009 [online version] [reprint] [table 1]
  2. Jahren, A.H., C.P. Conrad, N.C. Arens, G. Mora, and C. Lithgow-Bertelloni (2005), A plate tectonic mechanism for methane hydrate release along subduction zones, Earth and Planetary Science Letters, 236, 691-704, doi:10.1016/j.epsl.2005.06.009. [online version] [reprint]
  3. Conrad, C.P., and C. Lithgow-Bertelloni (2004), The temporal evolution of plate driving forces: Importance of "slab suction" versus "slab pull" during the Cenozoic, Journal of Geophysical Research, 109, B10407, doi:10.1029/2004JB002991. [online version] [reprint]
  4. Conrad, C.P., and C. Lithgow-Bertelloni (2002), How mantle slabs drive plate tectonics, Science, 298, 207-209, doi:10.1126/science.1074161. [online version] [reprint] [online supplement]
  5. Conrad, C.P., and B.H. Hager (2001), Mantle convection with strong subduction zones, Geophysical Journal International, 144, 271-288, doi:10.1046/j.1365-246x.2001.00321.x. [online version] [reprint]
  6. Conrad, C.P., and B.H. Hager (1999), Effects of plate bending and fault strength at subduction zones on plate dynamics, Journal of Geophysical Research, 104, 17551-17571, doi:10.1029/1999JB900149. [online version] [reprint]
  7. Conrad, C.P., and B.H. Hager (1999), The thermal evolution of an earth with strong subduction zones, Geophysical Research Letters, 26, 3041-3044, doi:10.1029/1999GL005397. [online version] [reprint]

Patterns of Global Seismicity


Patterns of Global Seismicity Earthquakes represent brittle deformation of the Earth's lithosphere in response to imposed stresses. Thus, observations of spatial and temporal patterns of seismicity can tell us something about lithospheric stresses. We have used observations of the timing and location of earthquakes to constrain the importance of tidal and tectonics stresses for lithospheric deformation. In particular, we have shown that earthquakes are slightly more common during certain phases of the earth tides, and that both large and deep subduction zone earthquakes are correlated to the tectonic environment at the subduction zone.
  1. Heuret, A., C.P. Conrad, F. Funiciello, S. Lallemand, and L. Sandri (2012), Relation between subduction megathrust earthquakes, trench sediment thickness and upper plate strain, Geophysical Research Letters, 39, L05304, doi:10.1029/2011GL050712. [online version] [reprint] [auxiliary material]
  2. Métivier, L., O. de Viron, C.P. Conrad, S. Renault, M. Diament, and G. Patau (2009), Evidence of earthquake triggering by the solid earth tides, Earth and Planetary Science Letters, 278, 370-375, doi:10.1016/j.epsl.2008.12.024. [online version] [reprint]
  3. Bilek, S.L., C.P. Conrad, and C. Lithgow-Bertelloni (2005), Slab pull, slab weakening, and their relation to deep intra-slab seismicity, Geophysical Research Letters, 32, L14305, doi:10.1029/2005GL022922. [online version] [reprint]
  4. Conrad, C.P., S. Bilek, and C. Lithgow-Bertelloni (2004), Great earthquakes and slab pull: interaction between seismic coupling and plate-slab coupling, Earth and Planetary Science Letters, 218, 109-122, doi:10.1016/S0012-821X(03)00643-5 [online version] [reprint]

Convective Instability


Convective Instability The upper and lower boundary layers to convection are gravitationally unstable. As a result, small-scale convective instability can develop on either boundary layer. For the top boundary layer, this instability takes the form of "drips" that descend from the dense lithosphere into the hotter mantle. This processes can remove the lower mantle lithosphere and ultimately lead to surface uplift and volcanism. For the lower boundary layer, this instability produces "plumes" that rise from the core-mantle-boundary and can eventually reach the surface, producing volcanism. We have investigated the fluid dynamics of both types of instability, and related them to observations of lithospheric drips and mantle plumes on Earth.
  1. Lithgow-Bertelloni, C., M.A. Richards, C.P. Conrad, and R.W. Griffiths (2001), Plume generation in natural and thermal convection at high Rayleigh and Prandtl numbers, Journal of Fluid Mechanics, 434, 1-21, doi:10.1017/S0022112001003706. [online version] [reprint]
  2. Conrad, C.P. (2000), Convective instability of thickening mantle lithosphere, Geophysical Journal International, 143, 52-70, doi:10.1046/j.1365-246x.2000.00214.x. [online version] [reprint]
  3. Conrad, C.P., and P. Molnar (1999), Convective instability of a boundary layer with temperature- and strain-rate-dependent viscosity in terms of "available buoyancy", Geophysical Journal International, 139, 51-68, doi:10.1046/j.1365-246X.1999.00896.x. [online version] [reprint]
  4. Molnar, P., G.A. Houseman, and C.P. Conrad (1998), Rayleigh-Taylor instability and convective thinning of mechanically thickened lithosphere: Effects of non-linear viscosity decreasing exponentially with depth and of horizontal shortening of the layer, Geophysical Journal International, 133, 568-584, doi:10.1046/j.1365-246X.1998.00510.x. [online version] [reprint]
  5. Conrad, C.P., and P. Molnar (1997), The growth of Rayleigh-Taylor-type instabilities in the lithosphere for various rheological and density structures, Geophysical Journal International, 129, 95-112, doi:10.1111/j.1365-246X.1997.tb00939.x. [online version] [reprint]
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