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. Regular Articles

    1. Top of page
    2. Regular Articles
    3. Research Article
    4. Research Articles
    5. Research Letters
    1. 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

      Article first published 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
    2. 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

      Article first published 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
  2. Research Article

    1. Top of page
    2. Regular Articles
    3. Research Article
    4. Research Articles
    5. Research Letters
    1. An upper-mantle seismic discontinuity beneath the Galápagos Archipelago and its implications for studies of the lithosphere-asthenosphere boundary

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

      Accepted manuscript online: 2 MAR 2015 03:17PM EST | DOI: 10.1002/2014GC005694

  3. Research Articles

    1. Top of page
    2. Regular Articles
    3. Research Article
    4. Research Articles
    5. Research Letters
    1. Lithospheric structure across the California Continental Borderland from receiver functions (pages 246–266)

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

      Article first published 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
    2. Microstructures, composition, and seismic properties of the Ontong Java Plateau mantle root (pages 4547–4569)

      Andréa Tommasi and Akira Ishikawa

      Article first published 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
    3. 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

      Article first published 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
    4. 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

      Article first published 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
    5. 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

      Article first published 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
    6. Intraplate volcanism at the edges of the Colorado Plateau sustained by a combination of triggered edge-driven convection and shear-driven upwelling

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

      Article first published 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
  4. Research Letters

    1. Top of page
    2. Regular Articles
    3. Research Article
    4. Research Articles
    5. Research Letters
    1. 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

      Article first published 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

      Article first published 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

      Article first published 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

      Article first published 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

      Article first published 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

      Article first published 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

      Article first published 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

      Article first published 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

      Article first published 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

      Article first published 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

      Article first published 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

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

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

      Article first published 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

      Article first published online: 4 JUN 2010 | DOI: 10.1029/2010GC003038

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