Shear wave splitting, continental keels, and patterns of mantle flow

被引:214
作者
Fouch, MJ
Fischer, KM
Parmentier, EM
Wysession, ME
Clarke, TJ
机构
[1] Brown Univ, Dept Geol Sci, Providence, RI 02912 USA
[2] Washington Univ, Dept Earth & Planetary Sci, St Louis, MO 63130 USA
[3] New Mexico Inst Min & Technol, Dept Earth & Environm Sci, Socorro, NM 87114 USA
关键词
D O I
10.1029/1999JB900372
中图分类号
P3 [地球物理学]; P59 [地球化学];
学科分类号
0708 ; 070902 ;
摘要
In this study we investigated the origin of seismic anisotropy in the mantle beneath North America. In particular, we evaluated whether shear wave splitting patterns in eastern North America are better explained by anisotropy caused by lithospheric deformation, anisotropy due to mantle flow beneath the lithosphere, or a combination of both. We examined new measurements of shear wave splitting from the Missouri to Massachusetts broadband seismometer array (MOMA), the North American Mantle Anisotropy and Discontinuity experiment (NOMAD), as well as splitting parameters from several previous studies. We developed a simple finite difference model that approximates mantle flow around a complex, three-dimensional continental lithospheric keel. To evaluate potential anisotropy from mantle flow beneath the lithosphere in eastern North America, we compared shear wave splitting observations to predicted splitting parameters calculated using this mantle flow model. Our results indicate that a significant portion of observed shear wave splitting in eastern North America can be explained by mantle flow around the continental keel. However, shear wave splitting patterns in a few regions of eastern North America indicate that a component of lithospheric anisotropy must exist, particularly in regions containing the largest keel thicknesses. For eastern North America, as well as for splitting observations in Australia, Europe, and South America, we favor a model in which anisotropy is controlled by a combination of both lithospheric deformation and subcontinental mantle flow.
引用
收藏
页码:6255 / 6275
页数:21
相关论文
共 81 条
[41]   ELASTIC MODULI, PRESSURE DERIVATIVES, AND TEMPERATURE DERIVATIVES OF SINGLE-CRYSTAL OLIVINE AND SINGLE-CRYSTAL FORSTERITE [J].
KUMAZAWA, M ;
ANDERSON, OL .
JOURNAL OF GEOPHYSICAL RESEARCH, 1969, 74 (25) :5961-+
[42]  
LARSON EWF, 1998, EOS T AGU S, V79, pS214
[43]   Seismic anisotropy in the north-eastern US as a source of significant teleseismic P traveltime anomalies [J].
Levin, V ;
Menke, W ;
LernerLam, A .
GEOPHYSICAL JOURNAL INTERNATIONAL, 1996, 126 (02) :593-603
[44]   Shear wave splitting in the Appalachians and the Urals: A case for multilayered anisotropy [J].
Levin, V ;
Menke, W ;
Park, J .
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, 1999, 104 (B8) :17975-17993
[45]  
LI A, 1999, EOS T AGU S, V80, pF730
[46]   Mantle discontinuities and temperature under the North American continental keel [J].
Li, AB ;
Fischer, KM ;
Wysession, ME ;
Clarke, TJ .
NATURE, 1998, 395 (6698) :160-163
[47]   INTERPRETATION OF SKS-WAVES USING SAMPLES FROM THE SUBCONTINENTAL LITHOSPHERE [J].
MAINPRICE, D ;
SILVER, PG .
PHYSICS OF THE EARTH AND PLANETARY INTERIORS, 1993, 78 (3-4) :257-280
[48]   LABORATORY AND SEISMOLOGICAL OBSERVATIONS OF LOWER MANTLE ISOTROPY [J].
MEADE, C ;
SILVER, PG ;
KANESHIMA, S .
GEOPHYSICAL RESEARCH LETTERS, 1995, 22 (10) :1293-1296
[49]   THE ANISOTROPIC STRUCTURE OF THE UPPER MANTLE IN THE PACIFIC [J].
NISHIMURA, CE ;
FORSYTH, DW .
GEOPHYSICAL JOURNAL-OXFORD, 1989, 96 (02) :203-229
[50]   STUDY OF SHALLOW GLOBAL MANTLE FLOW DUE TO THE ACCRETION AND SUBDUCTION OF LITHOSPHERIC PLATES [J].
PARMENTIER, EM ;
OLIVER, JE .
GEOPHYSICAL JOURNAL OF THE ROYAL ASTRONOMICAL SOCIETY, 1979, 57 (01) :1-21