Abstract
Throughout the oceanic asthenosphere there exists a zone of seismic velocities that are lower than would be predicted. The cause of this low velocity zone (LVZ), whether partial melt or solid-state mechanisms, has been debated for decades. We investigate the LVZ by considering seismic and magnetotelluric data from tectonically stable, ∼70 Myr old lithosphere in the central Pacific Ocean. We utilise recent experimental advances on the influence of partial melt and seismic attenuation. Results show that the LVZ is characterised by a small volume of interconnected melt and by low hydrogen contents. Beneath the LVZ, the asthenosphere does not contain partial melt but has high hydrogen contents and low attenuation values, indicating large grain sizes and/or low oxygen fugacities. To explain these observations, we propose that a small amount of unextractable melt is trapped in the asthenosphere after melting at mid-ocean ridges.
| Language | English |
|---|---|
| Pages | 117-124 |
| Number of pages | 8 |
| Journal | Earth and Planetary Science Letters |
| Volume | 517 |
| DOIs | |
| Publication status | Published - 1 Jul 2019 |
Fingerprint
Keywords
- asthenosphere
- mantle
- melt
- low velocity zone
- magnetotellurics
- seismic
Cite this
}
A small, unextractable melt fraction as the cause for the low velocity zone. / Selway, Kate; O'Donnell, J. P.
In: Earth and Planetary Science Letters, Vol. 517, 01.07.2019, p. 117-124.Research output: Contribution to journal › Article › Research › peer-review
TY - JOUR
T1 - A small, unextractable melt fraction as the cause for the low velocity zone
AU - Selway, Kate
AU - O'Donnell, J. P.
PY - 2019/7/1
Y1 - 2019/7/1
N2 - Throughout the oceanic asthenosphere there exists a zone of seismic velocities that are lower than would be predicted. The cause of this low velocity zone (LVZ), whether partial melt or solid-state mechanisms, has been debated for decades. We investigate the LVZ by considering seismic and magnetotelluric data from tectonically stable, ∼70 Myr old lithosphere in the central Pacific Ocean. We utilise recent experimental advances on the influence of partial melt and seismic attenuation. Results show that the LVZ is characterised by a small volume of interconnected melt and by low hydrogen contents. Beneath the LVZ, the asthenosphere does not contain partial melt but has high hydrogen contents and low attenuation values, indicating large grain sizes and/or low oxygen fugacities. To explain these observations, we propose that a small amount of unextractable melt is trapped in the asthenosphere after melting at mid-ocean ridges.
AB - Throughout the oceanic asthenosphere there exists a zone of seismic velocities that are lower than would be predicted. The cause of this low velocity zone (LVZ), whether partial melt or solid-state mechanisms, has been debated for decades. We investigate the LVZ by considering seismic and magnetotelluric data from tectonically stable, ∼70 Myr old lithosphere in the central Pacific Ocean. We utilise recent experimental advances on the influence of partial melt and seismic attenuation. Results show that the LVZ is characterised by a small volume of interconnected melt and by low hydrogen contents. Beneath the LVZ, the asthenosphere does not contain partial melt but has high hydrogen contents and low attenuation values, indicating large grain sizes and/or low oxygen fugacities. To explain these observations, we propose that a small amount of unextractable melt is trapped in the asthenosphere after melting at mid-ocean ridges.
KW - asthenosphere
KW - mantle
KW - melt
KW - low velocity zone
KW - magnetotellurics
KW - seismic
UR - http://www.scopus.com/inward/record.url?scp=85064906901&partnerID=8YFLogxK
UR - http://purl.org/au-research/grants/arc/FT150100541
U2 - 10.1016/j.epsl.2019.04.012
DO - 10.1016/j.epsl.2019.04.012
M3 - Article
VL - 517
SP - 117
EP - 124
JO - Earth and Planetary Science Letters
T2 - Earth and Planetary Science Letters
JF - Earth and Planetary Science Letters
SN - 0012-821X
ER -