TY - JOUR
T1 - High-resolution estimates of lithospheric thickness from Missouri to Massachusetts, USA
AU - Van der Lee, Suzan
N1 - Funding Information:
Ghassan Al-Eqabi introduced me to the MOMA data before they became publicly available. The IRIS DMC ( http://www.iris.edu ) provided the waveform data of the permanent stations used in this study. Walter Mooney generously made his database on North American crustal structure available. I am grateful to Karen Fischer for encouragement, and to Karen Fischer, Saskia Goes, David James, Aibing Li, Steve Miller, and Guust Nolet for useful comments on different versions of the manuscript. 3-D S-velocity model NA00 is available at http://www.sg.geophys.ethz.ch/geodynamics/suzan/na/ . This work was funded by the Carnegie Institution of Washington and by the Swiss Federal Institute of Technology (ETH). [RV]
PY - 2002/10/15
Y1 - 2002/10/15
N2 - This paper presents a new three-dimensional (3-D) model, NA00, of the S-velocity of the upper mantle beneath North America. The model differs from its predecessor NA95 in that it exploits seismograms recorded by a recent dense, broadband array, MOMA, and from independent measurements of North American crustal thickness. Model NA00 is derived by fitting the waveforms of broadband seismic S and surface waves recorded by the MOMA array and inverting them together with the database of waveform fits used for NA95 and the crustal thickness estimates. It is demonstrated that including data from the dense, broadband MOMA array yields a resolving power beneath the array that is of unprecedented quality and relatively constant over a large depth range. This improved resolution provides a unique opportunity for quantifying the structure of the upper mantle in and below the lower, thick Precambrian lithosphere. The high-resolution seismic structure of the imaged high-velocity lithosphere is compared with the thermal structure (estimated from heat flow), compositional structure (estimated from xenoliths and electrical conductivity) and the elastic structure (estimated from gravity and topography). There is a remarkable agreement between the seismic, thermal, and compositional estimates. The seismic lithosphere is 180 km thick below Missouri and Illinois, 200 km thick below Indiana, Ohio and Pennsylvania, practically undefined below New York, and 80 km below Massachusetts and the Atlantic continental shelf. The thick lithosphere is underlain by a layer with lower S-velocities that could represent a relatively low-viscosity channel. However, the S-velocities in this layer are much higher than those of typical oceanic asthenosphere.
AB - This paper presents a new three-dimensional (3-D) model, NA00, of the S-velocity of the upper mantle beneath North America. The model differs from its predecessor NA95 in that it exploits seismograms recorded by a recent dense, broadband array, MOMA, and from independent measurements of North American crustal thickness. Model NA00 is derived by fitting the waveforms of broadband seismic S and surface waves recorded by the MOMA array and inverting them together with the database of waveform fits used for NA95 and the crustal thickness estimates. It is demonstrated that including data from the dense, broadband MOMA array yields a resolving power beneath the array that is of unprecedented quality and relatively constant over a large depth range. This improved resolution provides a unique opportunity for quantifying the structure of the upper mantle in and below the lower, thick Precambrian lithosphere. The high-resolution seismic structure of the imaged high-velocity lithosphere is compared with the thermal structure (estimated from heat flow), compositional structure (estimated from xenoliths and electrical conductivity) and the elastic structure (estimated from gravity and topography). There is a remarkable agreement between the seismic, thermal, and compositional estimates. The seismic lithosphere is 180 km thick below Missouri and Illinois, 200 km thick below Indiana, Ohio and Pennsylvania, practically undefined below New York, and 80 km below Massachusetts and the Atlantic continental shelf. The thick lithosphere is underlain by a layer with lower S-velocities that could represent a relatively low-viscosity channel. However, the S-velocities in this layer are much higher than those of typical oceanic asthenosphere.
KW - Broad-brand spectra
KW - Lithosphere
KW - Low-velocity zones
KW - S-waves
KW - Thickness
KW - Tomography
KW - Waveforms
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U2 - 10.1016/S0012-821X(02)00846-4
DO - 10.1016/S0012-821X(02)00846-4
M3 - Article
AN - SCOPUS:0037107924
VL - 203
SP - 15
EP - 23
JO - Earth and Planetary Sciences Letters
JF - Earth and Planetary Sciences Letters
SN - 0012-821X
IS - 1
ER -