Shear wave splitting and subcontinental mantle deformation

splitting observations are interpreted in terms of the strain-induced lattice preferred orientation of mantle minerals, especially olivine. We consider three hypotheses concerning the origin of the continental anlsotropy: (1) strain associated with absolute plate motion, as in the oceanic upper mantle, (2) crustal stress, and (3) the past and present internal deformation of the subcontinental upper mantle by tectonic episodes. It is found that the last hypothesis is the most successful, namely that the most recent significant episode of internal deformation appears to be the best predictor of q. For stable continental regions, this is interpreted as "fossil" anisotropy, whereas for presently active regions, such as Alaska, the anisotropy reflects present-day tectonic activity. In the stable portion of North America there is a good correlation between delay time and lithospheric thickness; this is consistent with the anisotropy being localized in the subcontinental lithosphere and suggests that intrinsic anisotropy is approximately constant. The acceptance of this hypothesis has several implications for subcontinental mantle deformation. First, it argues for coherent deformation of the continental lithosphere (crust and mantle) during orogenies. This implies that the anisotropic portion of the lithosphere was present since the deformational episode and rules out the addition of undeformed material to this layer by subsequent "underplating" or conductive growth of the thermal boundary layer. One of the most important issues in the study of orogenies is the need to reconcile the formation of thickened lithosphere with the paradoxically high mantle temperatures often associated with orogenic episodes. Most efforts to date have focussed on modes of deformation whereby the cold lithospheric mantle is removed (by convective instability or delamination) and replaced by warm asthenosphere. These models, however, are incompatible with the evidence for preserved coherent lithospheric deformation; rather, the deformed mantle appears to have been heated in place. We suggest that the elevated mantle temperatures may be due to the strain heating accompanying the deformation.

[1]  Yang Yu,et al.  A theory for plastic deformation and textural evolution of olivine polycrystals , 1991 .

[2]  A. Vauchez,et al.  Mountain building: strike-parallel motion and mantle anisotropy , 1991 .

[3]  P. Silver,et al.  A Procedure For the Systematic Interpretation of Body Wave Seismograms-I. Application to Moho Depth and Crustal Properties , 1991 .

[4]  M. Barazangi,et al.  Azimuthal anisotropy of velocity in the mantle lid beneath the Basin and Range province , 1990, Nature.

[5]  K. Card.  A review of the Superior Province of the Canadian Shield, a product of Archean accretion , 1990 .

[6]  R. Gordon,et al.  Current plate velocities relative to the hotspots incorporating the NUVEL-1 global plate motion model , 1990 .

[7]  S. Kamo,et al.  U-Pb Ages on Single Detrital Zircon Grains from the Witwatersrand Basin, South Africa: Constraints on the Age of Sedimentation and on the Evolution of Granites Adjacent to the Basin , 1990, The Journal of Geology.

[8]  T. Tanimoto,et al.  Global anisotropy in the upper mantle inferred from the regionalization of phase velocities , 1990 .

[9]  P. Silver,et al.  Observations of teleseismic shear‐wave splitting in the basin and range from portable and permanent stations , 1990 .

[10]  Philip England,et al.  Extension during continental convergence, with application to the Tibetan Plateau , 1989 .

[11]  L. Vinnik,et al.  Azimuthal anisotropy in the lithosphere from observations of long-period S-waves , 1989 .

[12]  S. Kaneshima,et al.  An analysis of split shear waves observed above crustal and uppermost mantle earthquakes beneath Shikoku, Japan: Implications in effective depth extent of seismic anisotropy , 1989 .

[13]  B. Romanowicz,et al.  AZIMUTHAL ANISOTROPY IN THE EARTH FROM OBSERVATIONS OF SKS AT GEOSCOPE AND NARS BROADBAND STATIONS , 1989 .

[14]  O. Stephansson,et al.  Global patterns of tectonic stress , 1989, Nature.

[15]  R. Aster,et al.  Shear-wave anisotropy of active tectonic regions via automated S-wave polarization analysis , 1989 .

[16]  J. Schneider,et al.  An automated, analytical method to determine shear-wave splitting , 1989 .

[17]  C. Stein,et al.  SEASAT-derived gravity constraints on stress and deformation in the northeastern Indian Ocean , 1989 .

[18]  A. Nicolas,et al.  Structures of Ophiolites and Dynamics of Oceanic Lithosphere , 1989 .

[19]  H. Nataf,et al.  Anisotropy beneath 9 stations of the GEOSCOPE Broadband Network as deduced from shear-wave splitting , 1989 .

[20]  N. Ribe.  A Continuum Theory For Lattice Preferred Orientation , 1989 .

[21]  N. Ribe.  Seismic anisotropy and mantle flow , 1989 .

[22]  Richard G. Gordon,et al.  Current plate motions , 1990 .

[23]  D. B. Stone,et al.  Seismotectonics of northern Alaska , 1988 .

[24]  S. Kaneshima,et al.  Evidence from shear-wave splitting for the restriction of seismic anisotropy to the upper crust , 1988, Nature.

[25]  P. Molnar.  Continental tectonics in the aftermath of plate tectonics , 1988, Nature.

[26]  G. Ranalli,et al.  Archean oceanic flake tectonics , 1988 .

[27]  P. Molnar.  A review of geophysical constraints on the deep structure of the Tibetan Plateau, the Himalaya and the Karakoram, and their tectonic implications , 1988, Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences.

[28]  Paul G. Silver,et al.  Implications for continental structure and evolution from seismic anisotropy , 1988, Nature.

[29]  D. Gosselin,et al.  Archean rocks of the Black Hills, South Dakota: Reworked basement from the southern extension of the Trans-Hudson orogen , 1988 .

[30]  D. G. Watts,et al.  Nonlinear Regression Analysis and Its Applications , 1988 .

[31]  B. Isacks.  Uplift of the Central Andean Plateau and bending of the Bolivian orocline , 1988 .

[32]  P. Bird.  Formation of the Rocky Mountains, Western United States: A Continuum Computer Model , 1988, Science.

[33]  P. Molnar,et al.  Some simple physical aspects of the support, structure, and evolution of mountain belts , 1988 .

[34]  S. Grand.  Tomographic Inversion for Shear Velocity Beneath the North American Plate , 1987 .

[35]  S. R. Taylor,et al.  Crustal structure at Regional Seismic Test Network stations determined from inversion of broadband teleseismic P waveforms , 1987 .

[36]  Masataka Ando,et al.  Shear-wave splitting in the upper-mantle wedge above the Tonga subduction zone , 1987 .

[37]  S. Cloetingh,et al.  Stress in the Indo-Australian plate , 1986 .

[38]  John A. Orcutt,et al.  Compressional and shear wave anisotropy in the oceanic lithosphere - the Ngendei seismic refraction experiment , 1986 .

[39]  J. Davies,et al.  Additional evidence for down-dip tension in the Pacific plate beneath central Alaska , 1986 .

[40]  John E. Vidale,et al.  Complex polarization analysis of particle motion , 1986 .

[41]  Philip England,et al.  FINITE STRAIN CALCULATIONS OF CONTINENTAL DEFORMATION .2. COMPARISON WITH THE INDIA-ASIA COLLISION ZONE , 1986 .

[42]  J. A. Redden,et al.  Mineral resource potential and geology of the Black Hills National Forest, South Dakota and Wyoming, with a section on salable commodities , 1986 .

[43]  T. Kusky,et al.  Archean foreland basin tectonics in the Witwatersrand, South Africa , 1986 .

[44]  R. Kind,et al.  Observations of laterally inhomogeneous anisotropy in the continental lithosphere , 1985, Nature.

[45]  David C. Booth,et al.  Shear-wave polarizations near the North Anatolian Fault – II. Interpretation in terms of crack-induced anisotropy , 1985 .

[46]  D. Sandwell,et al.  Folding of oceanic lithosphere , 1985 .

[47]  L. Gedney.  Stress trajectories across the Northeast Alaska Range , 1985 .

[48]  T. Kusky,et al.  Is the Ventersdorp Rift System of Southern Africa related to a continental collision between the Kaapvaal and Zimbabwe Cratons at 2.64 Ga ago , 1985 .

[49]  Don L. Anderson,et al.  Lateral heterogeneity and azimuthal anisotropy of the upper mantle: Love and Rayleigh waves 100–250 s , 1985 .

[50]  J. B. Henderson.  Geology of the Yellowknife-Hearne Lake area, District of Mackenzie: a Segment Across An Archean Basin , 1985 .

[51]  P. Bird.  Laramide crustal thickening event in the Rocky Mountain Foreland and Great Plains , 1984 .

[52]  K. Weber,et al.  The Variscan Belt in Central Europe: Main structures, geodynamic implications, open questions , 1984 .

[53]  S. H. Richardson,et al.  Origin of diamonds in old enriched mantle , 1984, Nature.

[54]  Y. Fukao.  Evidence from core-reflected shear waves for anisotropy in the Earth's mantle , 1984, Nature.

[55]  Don L. Anderson,et al.  Anisotropy and shear-velocity heterogeneities in the upper mantle , 1984 .

[56]  M. Ando.  ScS POLARIZATION ANISOTROPY AROUND THE PACIFIC OCEAN , 1984 .

[57]  N. Christensen,et al.  The magnitude, symmetry and origin of upper mantle anisotropy based on fabric analyses of ultramafic tectonites , 1984 .

[58]  Fumihito Yamazaki,et al.  Shear wave polarization anisotropy in the upper mantle beneath Honshu, Japan , 1983 .

[59]  T. Jordan,et al.  Total‐moment spectra of fourteen large earthquakes , 1983 .

[60]  P. England.  Constraints on extension of continental lithosphere , 1983 .

[61]  K. Fuchs.  Recently formed elastic anisotropy and petrological models for the continental subcrustal lithosphere in southern Germany , 1983 .

[62]  P. England,et al.  A thin viscous sheet model for continental deformation , 1982 .

[63]  G. Eaton.  The Basin and Range Province: Origin and Tectonic Significance , 1982 .

[64]  M. Ando,et al.  OBSERVATIONS OF SHEAR-WAVE VELOCITY POLARIZATION ANISOTROPY BENEATH HONSHU, JAPAN , 1982 .

[65]  J. Minster,et al.  Pn velocity anisotropy in southern California , 1981 .

[66]  P. Molnar,et al.  Convective instability of a thickened boundary layer and its relevance for the thermal evolution of , 1981 .

[67]  D. L. Anderson,et al.  Preliminary reference earth model , 1981 .

[68]  M. Zoback,et al.  Cainozoic evolution of the state of stress and style of tectonism of the Basin and Range province of the western United States , 1981, Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences.

[69]  Mark D. Zoback,et al.  State of stress in the conterminous United States , 1980 .

[70]  D. Watts,et al.  OF THE VALLEY AND RIDGE PROVINCE OF THE APPALACHIAN MOUNTAINS , 1980 .

[71]  K. Jacob,et al.  A Tectonic Stress Trajectory Map of Alaska Using Information from Volcanoes and Faults , 1980 .

[72]  Y. Guéguen,et al.  Deformation of Mantle Rocks , 1980 .

[73]  C. Jaupart,et al.  The heat flow through oceanic and continental crust and the heat loss of the Earth , 1980 .

[74]  D. McKenzie,et al.  Finite deformation during fluid flow , 1979 .

[75]  D. Bamford,et al.  Pn anisotropy studies in northern Britain and the eastern and western United States , 1979 .

[76]  P. Bird.  Initiation of intracontinental subduction in the Himalaya , 1978 .

[77]  Thomas H. Jordan,et al.  Present‐day plate motions , 1977 .

[78]  D. Bamford.  Pn velocity anisotropy in a continental upper mantle , 1977 .

[79]  S. Crampin,et al.  Seismic body waves in anisotropic media: synthetic seismograms , 1977 .

[80]  Paul F. Williams,et al.  An Outline of Structural Geology , 1976 .

[81]  A. Nicolas,et al.  Crystalline plasticity and solid state flow in metamorphic rocks , 1976 .

[82]  Donald W. Forsyth.  The Early Structural Evolution and Anisotropy of the Oceanic Upper Mantle , 1975 .

[83]  F. Boudier,et al.  Mechanisms of flow in naturally and experimentally deformed peridotites , 1973 .

[84]  D. Kohlstedt,et al.  Laboratory study of dislocation climb and diffusion in olivine , 1973 .

[85]  Mineo Kumazawa,et al.  Elastic moduli, pressure derivatives, and temperature derivatives of single‐crystal olivine and single‐crystal forsterite , 1969 .

[86]  T. Francis,et al.  Anisotropy of the Pacific upper mantle , 1969 .

[87]  N. Christensen.  Shear wave velocities in metamorphic rocks at pressures to 10 kilobars , 1966 .

[88]  G. Backus.  Possible forms of seismic anisotropy of the uppermost mantle under oceans , 1965 .

[89]  H. H. Hess,et al.  Seismic Anisotropy of the Uppermost Mantle under Oceans , 1964, Nature.

[90]  R. Verma,et al.  Elasticity of some high-density crystals , 1960 .