Assessing the depth resolution of tomographic models of upper mantle structure beneath Iceland

[1] Earlier inversions of body wave delay-time data recorded during the ICEMELT portable broadband experiment imaged a cylindrical plume-like low-velocity anomaly extending to at least 400 km depth beneath Iceland, but the depth extent of the anomaly resolvable by tomography has recently been called into question. We have performed several additional resolution tests to evaluate the depth resolution of tomographic models of the Icelandic upper mantle. The distribution of paths of body waves recorded by ICEMELT can distinguish among three different types of models: (a) a wide and shallow anomaly, (b) a narrow and deep anomaly, and (c) a narrow and shallow anomaly. While tomographic models contain an element of nonuniqueness, these tests illustrate that the depth resolution of passive seismic experiments spanning subaerial Iceland is adequate for distinguishing among alternative geodynamic models.

[1]  J. Schilling.  Iceland Mantle Plume: Geochemical Study of Reykjanes Ridge , 1973, Nature.

[2]  D. L. Anderson,et al.  Resolution of tomographic models of the mantle beneath Iceland , 2000 .

[3]  J. Theissing,et al.  The dynamics of plume-ridge interaction, 1: Ridge-centered plumes , 1995 .

[4]  S. Solomon.  Department of terrestrial magnetism , 2000 .

[5]  D. Helmberger,et al.  Seismic evidence that the source of the Iceland hotspot lies at the core–mantle boundary , 1998, Nature.

[6]  C. Gable,et al.  Dynamics of mantle flow and melting at a ridge-centered hotspot: Iceland and the Mid-Atlantic Ridge , 1996 .

[7]  J. Woodhouse,et al.  Complex Shear Wave Velocity Structure Imaged Beneath Africa and Iceland. , 1999, Science.

[8]  J. Schilling.  Iceland Mantle Plume , 1973, Nature.

[9]  Harmen Bijwaard,et al.  Tomographic evidence for a narrow whole mantle plume below Iceland , 1999 .

[10]  C. Wolfe,et al.  Mantle flow, melting, and dehydration of the Iceland mantle plume , 1999 .

[11]  Marcelo Assumpção,et al.  Seismic evidence for a fossil mantle plume beneath South America and implications for plate driving forces , 1995, Nature.

[12]  S. Solomon,et al.  Initial results from the ICEMELT Experiment: Body‐wave delay times and shear‐wave splitting across Iceland , 1996 .

[13]  S. Solomon,et al.  Seismic evidence for a lower-mantle origin of the Iceland plume , 1998, Nature.

[14]  W. J. Morgan,et al.  Convection Plumes in the Lower Mantle , 1971, Nature.

[15]  E. Husebye,et al.  Seismic image of the hypothesized Icelandic hot spot , 1983 .

[16]  W. J. Morgan,et al.  The seismic anomaly beneath Iceland extends down to the mantle transition zone and no deeper , 2000 .

[17]  Sean C. Solomon,et al.  Seismic structure of the Iceland mantle plume , 1997, Nature.

[18]  J. Smallwood,et al.  The temperature of the Iceland plume and origin of outward-propagating V-shaped ridges , 1995, Journal of the Geological Society.