Seismic array detection of subducted oceanic crust in the lower mantle
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چکیده
منابع مشابه
Seismic array detection of subducted oceanic crust in the lower mantle
[1] We analyze short-period precursory energy to PP that can be observed in seismograms in the distance range from 95 to 105 to infer the behavior of subducted slabs beneath western Pacific subduction zones. PP is a P wave once reflected at the free surface between the source and receiver. Using high-resolution seismic array techniques, we analyze the incidence angle, timing, and azimuth of the...
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[1] Seismic tomography has revealed two large low shear velocity provinces (LLSVPs) in the lowermost mantle beneath the central Pacific and Africa. The LLSVPs are further shown to be compositionally different from their surroundings. Among several hypotheses put forth in recent years to explain the cause of the LLSVPs, one postulates that they are thermochemical piles caused by accumulation of ...
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The average chemical compositions of the continental crust and the oceanic crust (represented by MORB), normalized to primitive mantle values and plotted as functions of the apparent bulk partition coefficient of each element, form surprisingly simple, complementary concentration patterns. In the continental crust, the maximum concentrations are on the order of 50 to 100 times the primitive-man...
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[1] High-pressure assemblages of subducted oceanic crust are denser than the normal upper mantle but less dense than the uppermost lower mantle. Thus subducted oceanic crust may accumulate at the base of the upper mantle. Direct observational evidence for this hypothesis, however, remains elusive. We present an analysis of a negativepolarity shear wave converted from compressional wave at a sei...
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Article history: Received 13 March 2014 Received in revised form 4 June 2014 Accepted 8 June 2014 Available online xxxx Editor: Y. Ricard
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ژورنال
عنوان ژورنال: Journal of Geophysical Research
سال: 2008
ISSN: 0148-0227
DOI: 10.1029/2007jb005263