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Seismic detection of a thin laterally varying boundary layer at the base of the mantle beneath the central‐Pacific
| Content Provider | Semantic Scholar |
|---|---|
| Author | Garnero, Edward J. Helmberger, Donald V. |
| Copyright Year | 1996 |
| Abstract | We explore lowermost mantle structure beneath the Pacific with long‐period recordings of the seismic core phases SKS, SP_dKS, and SKKS from 25 deep earthquakes. SP_dKS and SKKS are anomalously delayed relative to SKS for lower mantle paths beneath the southwest Pacific. Late SP_dKS arrivals are explained by a laterally varying mantle‐side boundary layer at the CMB, having P‐velocity reductions of up to 10% and thickness up to 40 km. This layer is detected beneath a tomographically resolved large‐scale low velocity feature in the lower mantle beneath the central‐Pacific. SKS, SP_dKS, and SKKS data for the generally faster‐than‐average circum‐Pacific lower mantle are well‐fit by models lacking any such low‐velocity boundary layer. The slow boundary layer beneath the central Pacific may be a localized zone of partial melt, or perhaps a chemically distinct layer, with its location linked to overlying upwelling motions. |
| Starting Page | 977 |
| Ending Page | 980 |
| Page Count | 4 |
| File Format | PDF HTM / HTML |
| DOI | 10.1029/95GL03603 |
| Volume Number | 23 |
| Alternate Webpage(s) | http://authors.library.caltech.edu/35689/1/95GL03603.pdf |
| Alternate Webpage(s) | https://doi.org/10.1029/95GL03603 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
