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Unsuccessful initial search for a midmantle chemical boundary with seismic arrays

Geophysical Research Letters

By:
, , and
DOI: 10.1029/2000GL012428

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Abstract

Compositional layering of the midmantle has been proposed to account for seismic and geochemical patterns [van der Hilst and Karason, 1999], and inferred radiogenic heat source concentrations [Kellogg et al., 1999]. Compositional layering would require thermal boundary layers both above and below an interface. We construct a minimal 1-D model of a mid-mantle boundary consistent with the observed nearly adiabatic compressional velocity structure [Dziewonksi and Anderson, 1981] and the proposed high heat flow from the lower mantle [Albarede and van der Hilst, 1999; Kellogg et al., 1999]. Ray tracing and reflectivity synthetic seismograms show that a distinct triplication is predicted for short-period P waves. Although topography on a boundary would cause uncertainty in the strength and the range of the triplication, many clear observations would be expected. We examine data from the US West Coast regional networks in the most likely distance range of 60?? to 70?? for a 1770-km-depth boundary, and find no evidence for P wave triplications.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Unsuccessful initial search for a midmantle chemical boundary with seismic arrays
Series title:
Geophysical Research Letters
DOI:
10.1029/2000GL012428
Volume
28
Issue:
5
Year Published:
2001
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Geophysical Research Letters
First page:
859
Last page:
862
Number of Pages:
4