| Autor: |
Pasan Herath, Tim A. Stern, Martha K. Savage, Dan Bassett, Stuart Henrys |
| Rok vydání: |
2022 |
| Předmět: |
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| Zdroj: |
Science advances. 8(38) |
| ISSN: |
2375-2548 |
| Popis: |
New wide-angle seismic reflection data from offshore New Zealand show that the lithosphere-asthenosphere boundary (LAB) is more structured than previously thought. Three distinct layers are interpreted within a 10- to 12-km-thick LAB zone beginning at a depth of ≈70 km: a 3 (±1)–km-thick layer at the bottom of the lithosphere with a P-wave ( V P ) azimuthal anisotropy of 14 to 17% and fast azimuth subparallel to the direction of absolute plate motion and a 9 (±2)–km-thick, low V P channel with a P-wave–to–S-wave velocity ratio ( V P / V S ) of >2.8 in the upper 7 km of the channel and 1.8 to 2.6 in the lower 2 km of the channel. The high V P / V S ratios indicate that this channel may contain 3 to 20% partial melt that facilitates decoupling of the lithosphere from the asthenosphere and reduces resistance for plate motion. Furthermore, the strong azimuthal anisotropy above the low-velocity layer suggests localization of strain due to melt accumulation. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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