Geochemistry, Geophysics, Geosystems

Geochemistry, Geophysics, Geosystems

The Lithosphere-Asthenosphere System

Lithosphere and asthenosphere are fundamental concepts of plate tectonics and continental evolution, yet their properties, origin, and evolution are poorly understood. This special section is on the multi-disciplinary observations and models that pertain to the concept of the lithosphere-asthenosphere system, and in particular the lithosphere-asthenosphere boundary (LAB), as well as possible mid-lithospheric discontinuities (MLD). This theme expands on a successful previous one on the "Lithosphere asthenosphere boundary", and the recent workshop on the "Structure and Dynamics of the Lithosphere-Asthenosphere System" serves to highlight some of the remaining issues. This workshop was held at the College de France, Paris, in November 2013 (organizers: B. Romanowicz and C. Jaupart), and contributions from workshop participants are particularly, but not exclusively, encouraged. We invite submissions from all disciplines discussing the nature and evolution of the MLD and LAB, and the dynamic interactions of the lithosphere with the crust and mantle throughout Earth history, within the context of mantle convection and fractionation.

  1. Comment

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      Comment on “Nature of the Seismic Lithosphere-Asthenosphere Boundary within Normal Oceanic Mantle from High-Resolution Receiver Functions” by Olugboji et al. (pages 3488–3492)

      Hitoshi Kawakatsu and Yuki Abe

      Version of Record online: 12 AUG 2016 | DOI: 10.1002/2016GC006418

      Key Points:

      • Sediment reverberations are significant and severe for some of OBS data analyzed by Olugboji et al. [2016, G-cubed]
      • Without considering this effect, discussion on the mantle structure below is highly questionable
      • We recommend the authors to consider this effect in their modeling, or at least to show how the effect is observed in all the analyzed data
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      Seismic evidence for stratification in composition and anisotropic fabric within the thick lithosphere of Kalahari Craton (pages 5393–5412)

      Forough Sodoudi, Xiaohui Yuan, Rainer Kind, Sergei Lebedev, Joanne M.-C. Adam, Emanuel Kästle and Frederik Tilmann

      Version of Record online: 26 DEC 2013 | DOI: 10.1002/2013GC004955

      Key Points

      • Kalahari Craton has a thick and stratified mantle lithosphere
      • Three negative discontinuities were detected within the mantle lithosphere
      • Frozen-in anisotropy and compositional changes generate sharp discontinuities
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      Scandinavia: A former Tibet? (pages 4479–4487)

      R. Kind, F. Sodoudi, X. Yuan, H. Shomali, R. Roberts, D. Gee, T. Eken, M. Bianchi, F. Tilmann, N. Balling, B. H. Jacobsen, P. Kumar and W. H. Geissler

      Version of Record online: 7 OCT 2013 | DOI: 10.1002/ggge.20251

      Key Points

      • Layered structure of the mantle lithosphere in Scandinavia
      • Remnants of old subduction below Scandinavia
      • S receiver function technique resolves structure of cratons
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      Reply to comment by Kawakatsu and Abe on “Nature of the seismic lithosphere-asthenosphere boundary within normal oceanic mantle from high-resolution receiver functions” (pages 3493–3501)

      Tolulope Morayo Olugboji, Jeffrey Park and Shun-ichiro Karato

      Version of Record online: 12 AUG 2016 | DOI: 10.1002/2016GC006453

      Key Points

      • Effect of sediment resonance on ocean bottom receiver functions
      • Distinguishing between sediment reverberation and the “seismic-LAB”
      • Move-out stacking of constant RF mutes reverberations
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    1. Lithospheric thickness estimation beneath Northwestern South America from an S-wave receiver function analysis (pages 1376–1387)

      J. Faustino Blanco, Carlos A. Vargas and Gaspar Monsalve

      Version of Record online: 3 APR 2017 | DOI: 10.1002/2016GC006785

      Key Points

      • The depth of the LAB was estimated beneath northwestern South America from S-wave receiver functions
      • LAB depths vary between 65 km beneath the Ecuador-Colombia Trench and 110 km in some highly deformed areas of the Northern Andes
      • There are not significant variations in lithospheric thickness among different regions of the Northern Andes
    2. Conductivity structure of the lithosphere-asthenosphere boundary beneath the eastern North American margin (pages 676–696)

      Eric Attias, Rob. L. Evans, Samer Naif, Jimmy Elsenbeck and Kerry Key

      Version of Record online: 25 FEB 2017 | DOI: 10.1002/2016GC006667

      Key Points

      • LAB topography varies between ∼85 and 145 km depth
      • A thin lithosphere is associated with a zone of anomalous conductivity
      • The lithospheric anomalous conductivity zone (LACZ) possibly results from kimberlite intrusions or alteration in rheology due to localized rift-related deformation
    3. Crustal structure and extension mode in the northwestern margin of the South China Sea (pages 2143–2167)

      Jinwei Gao, Shiguo Wu, Kirk McIntosh, Lijun Mi, Zheng Liu and George Spence

      Version of Record online: 18 JUN 2016 | DOI: 10.1002/2016GC006247

      Key Points

      • Multichannel seismic reflection and satellite gravity data in the northwestern South China Sea
      • Seismic images and gravity modeling indicate a hyper-extended continental margin
      • Mantle-lithosphere may break up before crustal-necking in the northwestern South China Sea margin
    4. Nature of the seismic lithosphere-asthenosphere boundary within normal oceanic mantle from high-resolution receiver functions (pages 1265–1282)

      Tolulope Morayo Olugboji, Jeffrey Park, Shun-ichiro Karato and Masanao Shinohara

      Version of Record online: 6 APR 2016 | DOI: 10.1002/2015GC006214

      Key Points:

      • Age dependence in depth and sharpness of the lithosphere-asthenosphere boundary
      • The width of the velocity gradient is consistent with the grain-boundary sliding mechanism
      • Synthetic modeling of harmonically decomposed receiver functions guided by parameter search
    5. Multiscale seismic heterogeneity in the continental lithosphere (pages 791–809)

      B. L. N. Kennett and T. Furumura

      Version of Record online: 10 MAR 2016 | DOI: 10.1002/2015GC006200

      Key Points:

      • A multiscale heterogeneity model for continental lithosphere built on tomographic results
      • Matches character of observations for both horizontal and vertical propagation
      • No strong fine-scale seismic heterogeneity required, change in style at base of lithosphere
    6. Questions on the existence, persistence, and mechanical effects of a very small melt fraction in the asthenosphere (pages 470–484)

      Benjamin K. Holtzman

      Version of Record online: 17 FEB 2016 | DOI: 10.1002/2015GC006102

      Key Points:

      • A very small melt fraction in a network has a dramatic effect on the diffusion creep viscosity
      • This melt is stabilized by volatiles and surface tension will prevent it from being drained
      • The effect of melt on anelastic behavior can explain seismic structure in the shallow upper mantle
    7. The meaning of midlithospheric discontinuities: A case study in the northern U.S. craton (pages 4057–4083)

      Emily Hopper and Karen M. Fischer

      Version of Record online: 7 DEC 2015 | DOI: 10.1002/2015GC006030

      Key Points:

      • Northern U.S. cratonic mantle discontinuities are imaged by Sp converted waves
      • Four distinct classes of lithospheric discontinuity are observed
      • Cratonic mantle grew by subduction-related processes, at least in Proterozoic
    8. How partial melting affects small-scale convection in a plume-fed sublithospheric layer beneath fast-moving plates (pages 3924–3945)

      Roberto Agrusta, Andrea Tommasi, Diane Arcay, Alicia Gonzalez and Taras Gerya

      Version of Record online: 14 NOV 2015 | DOI: 10.1002/2015GC005967

      Key Points:

      • Partial melting does not enhance basal erosion of the plate, but changes its location
      • Buoyancy increase due to melt retention and depletion accelerates the onset, melt weakening not
      • Latent heat of melting and accumulation of strongly depleted material delay the SSC onset
    9. Characterization and Petrological Constraints of the Midlithospheric Discontinuity (pages 3484–3504)

      Erika Rader, Erica Emry, Nicholas Schmerr, Daniel Frost, Cheng Cheng, Julie Menard, Chun-Quan Yu and Dennis Geist

      Version of Record online: 20 OCT 2015 | DOI: 10.1002/2015GC005943

      Key Points:

      • MLD is found at consistent depths below cratons
      • Xenoliths from this horizon contain hydrous minerals
      • Hydrous minerals are trapped when melt cools
    10. Toward the reconciliation of seismological and petrological perspectives on oceanic lithosphere heterogeneity (pages 3129–3141)

      B. L. N. Kennett and T. Furumura

      Version of Record online: 20 SEP 2015 | DOI: 10.1002/2015GC006017

      Key Points:

      • A unified model for fine-scale heterogeneity in the oceanic lithosphere
      • Stronger heterogeneity near base of lithosphere links to changes in radial anisotropy
      • Expected age dependence in nature of fine-scale heterogeneity
    11. Lithospheric architecture beneath Hudson Bay (pages 2262–2275)

      Robert W. Porritt, Meghan S. Miller and Fiona A. Darbyshire

      Version of Record online: 14 JUL 2015 | DOI: 10.1002/2015GC005845

      Key Points:

      • The thick lithosphere of Hudson Bay has significant structural variation
      • We directly image the thermal blanketing on the asthenosphere
      • The lithospheric thickness of Hudson Bay is 200–350 km
    12. Plume-cratonic lithosphere interaction recorded by water and other trace elements in peridotite xenoliths from the Labait volcano, Tanzania (pages 1687–1710)

      Hejiu Hui, Anne H. Peslier, Roberta L. Rudnick, Antonio Simonetti and Clive R. Neal

      Version of Record online: 4 JUN 2015 | DOI: 10.1002/2015GC005779

      Key Points:

      • The Tanzanian craton has one of the driest cratonic lithosphere yet analyzed
      • Craton-plume interaction may not cause significant hydration of craton
      • High T may be responsible for lowering the cratonic root viscosity at Labait
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      Water in Hawaiian peridotite minerals: A case for a dry metasomatized oceanic mantle lithosphere (pages 1211–1232)

      Anne H. Peslier and Michael Bizimis

      Version of Record online: 30 APR 2015 | DOI: 10.1002/2015GC005780

      Key Points:

      • The oceanic mantle lithosphere above plumes is not enriched in water
      • Hawaiian peridotite water contents are on the low side of the MORB source
      • Metasomatized oceanic lithosphere has lower H2O/Ce than the MORB source
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      The thinning of subcontinental lithosphere: The roles of plume impact and metasomatic weakening (pages 1156–1171)

      Hongliang Wang, Jeroen van Hunen and D. Graham Pearson

      Version of Record online: 28 APR 2015 | DOI: 10.1002/2015GC005784

      Key Points:

      • The hypothesis that mantle plume remove continental lithosphere is tested
      • The effect of mechanical erosion by plumes on cratonic root is very limited
      • Metasomatism weakening is essential to remove originally stable lithosphere
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      The electrical structure of the central Pacific upper mantle constrained by the NoMelt experiment (pages 1115–1132)

      Emily Sarafian, Rob. L. Evans, John A. Collins, Jimmy Elsenbeck, Glenn A. Gaetani, James B. Gaherty, Greg Hirth and Daniel Lizarralde

      Version of Record online: 18 APR 2015 | DOI: 10.1002/2014GC005709

      Key Points:

      • MT data in the Pacific constrain lithospheric thickness and mantle structure
      • The observed conductivity is used to estimate asthenospheric water content
      • The electrical LAB lacks a highly conductive layer indicative of melt
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      An upper mantle seismic discontinuity beneath the Galápagos Archipelago and its implications for studies of the lithosphere-asthenosphere boundary (pages 1070–1088)

      Joseph S. Byrnes, Emilie E. E. Hooft, Douglas R. Toomey, Darwin R. Villagómez, Dennis J. Geist and Sean C. Solomon

      Version of Record online: 11 APR 2015 | DOI: 10.1002/2014GC005694

      Key Points:

      • A discontinuous decrease in wave speed with depth marks the base of dry mantle
      • The base of dry mantle is deeper over the plume than under the spreading center
      • Mantle upwelling and melting occur above the seismic discontinuity
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      Intraplate volcanism at the edges of the Colorado Plateau sustained by a combination of triggered edge-driven convection and shear-driven upwelling (pages 366–379)

      Maxim D. Ballmer, Clinton P. Conrad, Eugene I. Smith and Racheal Johnsen

      Version of Record online: 5 FEB 2015 | DOI: 10.1002/2014GC005641

      Key Points:

      • Edge-driven convection and shear-driven upwelling can sustain mantle melting
      • Such a combination can feed volcanism along the margins of the Colorado Plateau
      • Asthenospheric shearing and viscosity heterogeneity are sufficient for magmatism
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      Lithospheric structure across the California Continental Borderland from receiver functions (pages 246–266)

      Zachary Reeves, Vedran Lekić, Nicholas Schmerr, Monica Kohler and Dayanthie Weeraratne

      Version of Record online: 30 JAN 2015 | DOI: 10.1002/2014GC005617

      Key Points:

      • We map variations in lithospheric structure across Continental Borderland
      • Structure of Outer Borderland lithosphere rules out substantial extension
      • Lithospheric thickness of young Pacific plate indicates weak age-dependence
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      Microstructures, composition, and seismic properties of the Ontong Java Plateau mantle root (pages 4547–4569)

      Andréa Tommasi and Akira Ishikawa

      Version of Record online: 28 NOV 2014 | DOI: 10.1002/2014GC005452

      Key Points

      • Complete sampling of the Ontong Java mantle root from 56 to 120 km depth
      • Calculated velocities inconsistent with low velocities imaged seismologically
      • Change in anisotropy may produce an intralithospheric reflector
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      Integrated geophysical-petrological modeling of lithosphere-asthenosphere boundary in central Tibet using electromagnetic and seismic data (pages 3965–3988)

      Jan Vozar, Alan G. Jones, Javier Fullea, Matthew R. Agius, Sergei Lebedev, Florian Le Pape and Wenbo Wei

      Version of Record online: 24 OCT 2014 | DOI: 10.1002/2014GC005365

      Key Points

      • Joint modeling of Tibetan magnetotelluric and seismic data in petrologically consistent manner
      • Lithosphere-asthenosphere boundary in central Tibet
      • Estimates of water content in the Tibetan lithosphere
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      Three-dimensional electrical structure of the crust and upper mantle in Ordos Block and adjacent area: Evidence of regional lithospheric modification (pages 2414–2425)

      Hao Dong, Wenbo Wei, Gaofeng Ye, Sheng Jin, Alan G. Jones, Jianen Jing, Letian Zhang, Chengliang Xie, Fan Zhang and Hui Wang

      Version of Record online: 16 JUN 2014 | DOI: 10.1002/2014GC005270

      Key Points

      • 3D Modeling of the Ordos Block using SINOPROBE magnetotelluric array dataset
      • Conductor found beneath north Ordos suggests local lithosphere modification
      • The modification may be relevant to the destruction of North China Craton
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      Crustal thickness and velocity structure across the Moroccan Atlas from long offset wide-angle reflection seismic data: The SIMA experiment (pages 1698–1717)

      P. Ayarza, R. Carbonell, A. Teixell, I. Palomeras, D. Martí, A. Kchikach, M. Harnafi, A. Levander, J. Gallart, M. L. Arboleya, J. Alcalde, M. Fernández, M. Charroud and M. Amrhar

      Version of Record online: 7 MAY 2014 | DOI: 10.1002/2013GC005164

      Key Points

      • A crustal-scale imbrication has been identified in the Moroccan Atlas Mountains
      • Very low P-wave velocities in the lower crust and mantle of the Moroccan Atlas
      • The new Moho depth implies slight modifications to the LAB depth
  5. Research Letters

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      Is the electrical conductivity of the northwestern Pacific upper mantle normal? (pages 4969–4979)

      Kiyoshi Baba, Noriko Tada, Luolei Zhang, Pengfei Liang, Hisayoshi Shimizu and Hisashi Utada

      Version of Record online: 11 DEC 2013 | DOI: 10.1002/2013GC004997

      Key Points

      • Electrical structure of old northwestern Pacific upper mantle was investigated
      • The model was compared with that for other area in the western Pacific
      • The difference in the models cannot be explained by a plate cooling with age
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      The Pacific lithosphere-asthenosphere boundary: Seismic imaging and anisotropic constraints from SS waveforms

      Catherine A. Rychert, Nicholas Schmerr and Nicholas Harmon

      Version of Record online: 21 SEP 2012 | DOI: 10.1029/2012GC004194

      Key Points

      • New studies image Pacific LAB, but age-depth dependance/mechanism are unclear
      • Anisotropy explains apparent discrepancies in presence/absence of a strong LAB
      • Anisotropy is an important factor in imaging and defining the oceanic LAB
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      Lithospheric structure in the Baikal–central Mongolia region from integrated geophysical-petrological inversion of surface-wave data and topographic elevation

      J. Fullea, S. Lebedev, M. R. Agius, A. G. Jones and J. C. Afonso

      Version of Record online: 7 AUG 2012 | DOI: 10.1029/2012GC004138

      Key Points

      • Petro-physical inversion reduces non-uniqueness of seismic surface-wave inversion
      • No evidence for thermal anomaly in the uppermost mantle in central Mongolia
      • Topography is consistent with local isostasy with no dynamic component required
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      Melt infiltration of the lower lithosphere beneath the Tanzania craton and the Albertine rift inferred from S receiver functions

      Ingo Wölbern, Georg Rümpker, Klemens Link and Forough Sodoudi

      Version of Record online: 4 AUG 2012 | DOI: 10.1029/2012GC004167

      Key Points

      • Two consecutive velocity reductions in the lithosphere beneath East Africa
      • Infiltration of melts into the lower lithosphere crystallized in vein networks
      • Alteration of the lower lithosphere by means of metasomatism
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      Evolutionary aspects of lithosphere discontinuity structure in the western U.S.

      Alan Levander and Meghan S. Miller

      Version of Record online: 21 JUL 2012 | DOI: 10.1029/2012GC004056

      Key Points

      • LAB depth is correlated to Cordilleran hinge line
      • Moho and LAB west of hinge line are Cenozoic
      • Volcanism and deformation are localized along lithospheric thickness gradients
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      Lithosphere versus asthenosphere mantle sources at the Big Pine Volcanic Field, California

      Esteban Gazel, Terry Plank, Donald W. Forsyth, Claire Bendersky, Cin-Ty A. Lee and Erik H. Hauri

      Version of Record online: 27 JUN 2012 | DOI: 10.1029/2012GC004060

      Key Points

      • This is the first report of H2O, CO2 and oxidation state of BPVF magmas
      • BPVF melts record the stratigraphy of the lithosphere versus asthenosphere sources
      • Melting pressure and temperature correlates with shear wave seimic tomography
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      Upper mantle P velocity structure beneath the Midwestern United States derived from triplicated waveforms

      Risheng Chu, Brandon Schmandt and Don V. Helmberger

      Version of Record online: 18 FEB 2012 | DOI: 10.1029/2011GC003818

      Key Points

      • The lithosphere of the North American continent is about 165 km
      • The 660 discontinuity consists of two small discontinuities
      • A low-velocity zone is found on top of the 410 discontinuity beneath Wisconsin
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      The importance of slab pull and a global asthenosphere to plate motions

      Joost van Summeren, Clinton P. Conrad and Carolina Lithgow-Bertelloni

      Version of Record online: 1 FEB 2012 | DOI: 10.1029/2011GC003873

      Key Points

      • Even the deepest continental roots are underlain by a low-viscosity layer
      • About half of upper mantle slab weight needs to contribute to slab pull forces
      • With anchoring roots, predicted plate motions differ from the observations
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      Viscous coupling at the lithosphere-asthenosphere boundary

      Tobias Höink, A. Mark Jellinek and Adrian Lenardic

      Version of Record online: 27 OCT 2011 | DOI: 10.1029/2011GC003698

      Key Points

      • Scaling analysis shows viscous coupling at the LAB can explain plate velocities
      • Lateral pressure gradients lead to a plate driving force for small plates
      • Implications for asthenosphere properties, ridge topography, and thermal evolution
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      Seismically observable features of mature stagnant-lid convection at the base of the lithosphere: Some scaling relationships

      Norman H. Sleep

      Version of Record online: 25 OCT 2011 | DOI: 10.1029/2011GC003760

      Key Points

      • Downwelling material from stagnant lid convection likely detectable
      • Scalloped relief develops at base of lithosphere
      • Earth in parameter range where shear modestly aligns convection rolls
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      Seismic shear wave structure of the uppermost mantle beneath the Mohns Ridge

      Michaela M. Conley and Robert A. Dunn

      Version of Record online: 21 OCT 2011 | DOI: 10.1029/2011GC003792

      Key Points

      • Mohns lithospheric thickness is consistent with a half-space cooling model
      • Asthenosphere velocities agree with a half-space cooling model plus <2% melt
      • Melts are trapped below thin lithospheric lid at the ridge axis
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      Imaging crustal and upper mantle structure beneath the Colorado Plateau using finite frequency Rayleigh wave tomography

      Kaijian Liu, Alan Levander, Fenglin Niu and Meghan S. Miller

      Version of Record online: 1 JUL 2011 | DOI: 10.1029/2011GC003611

      Key Points

      • We develop a new Vs model using Rayleigh wave tomography in Colorado Plateau
      • Vs is strongly lateral heterogeneous, with low Vs margins and high Vs core
      • Vs structure results from edge convection and/or lithospheric downwelling
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      Imaging the seismic lithosphere-asthenosphere boundary of the oceanic plate

      Prakash Kumar and Hitoshi Kawakatsu

      Version of Record online: 27 JAN 2011 | DOI: 10.1029/2010GC003358

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      A mechanism for low-extent melts at the lithosphere-asthenosphere boundary

      Christy B. Till, Linda T. Elkins-Tanton and Karen M. Fischer

      Version of Record online: 27 OCT 2010 | DOI: 10.1029/2010GC003234

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      Constraints on upper mantle viscosity from the flow-induced pressure gradient across the Australian continental keel

      Christopher Harig, Shijie Zhong and Frederik J. Simons

      Version of Record online: 4 JUN 2010 | DOI: 10.1029/2010GC003038