Allen, RW;
Collier, JS;
Henstock, TJ;
(2022)
The Role of Crustal Accretion Variations in Determining Slab Hydration at an Atlantic Subduction Zone.
Journal of Geophysical Research: Solid Earth
, 127
(8)
, Article e2022JB024349. 10.1029/2022jb024349.
Preview |
PDF
JGR Solid Earth - 2022 - Allen - The Role of Crustal Accretion Variations in Determining Slab Hydration at an Atlantic.pdf - Published Version Download (16MB) | Preview |
Abstract
We present a 2D P-wave velocity model from the outer rise region of the Lesser Antilles island arc, the first wide-angle seismic study of outer rise processes at an Atlantic subduction zone. The survey consists of 46 OBS receivers over a 174 km profile with velocities resolved to 15 km below top basement. The final velocity model, produced through tomographic inversion, shows a clear decrease in the velocity of the lower crust and upper mantle of the incoming plate as it approaches the trench. We attribute this drop to outer rise bend-related hydration, similar to Pacific cases, but superimposed on spatial variations in hydration generated at the slow-spreading ridge axis. In thin, tectonically controlled crust formed under magma-poor spreading conditions the superposition of these sources of hydration results in compressional velocities as low as 6.5 km s −1 beneath the PmP reflector. In contrast, segments of crust interpreted as having formed under magma-rich conditions show velocity reductions and inferred hydrous alteration more like that observed in the Pacific. Hence, variations in the style of crustal accretion, which is observed on 50–100 km length scales both along and across isochrons, is a primary control over the distribution of water within the slab at Atlantic subduction systems. This heterogeneous pattern of water storage within the slab is likely further complicated by along strike variations in outer rise bending, subducting fracture zones and deformation at segment ends and may have important implications for our understanding of long-term patterns of hazard at Atlantic subduction systems.
| Type: | Article |
|---|---|
| Title: | The Role of Crustal Accretion Variations in Determining Slab Hydration at an Atlantic Subduction Zone |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1029/2022jb024349 |
| Publisher version: | https://doi. org/10.1029/2022JB024349 |
| Language: | English |
| Additional information: | This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third-party material in this article are included in the Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/ |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Earth Sciences |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10167691 |
Archive Staff Only
 |
View Item |
