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Seismic discontinuities across the North American Caribbean plate boundary from S-to-P receiver functions

Seismic discontinuities across the North American Caribbean plate boundary from S-to-P receiver functions
Seismic discontinuities across the North American Caribbean plate boundary from S-to-P receiver functions
The evolution of the Caribbean plate has resulted in the formation of volcanic arcs, the Caribbean Large Igneous Province (CLIP) and micro-plates across the plate boundary zones. The northern plate boundary with the North American plate has been particularly segmented with the transition from oblique subduction to oblique collision moving from east to west. However, there are few constraints on the seismic structure of the upper mantle across the plate boundary. Here we use S-to-P receiver functions to map seismic velocity discontinuities across the plate boundary, placing constraints on crustal and lithospheric thicknesses, as well as the structures associated with subduction and collision. We image a velocity increase with depth, consistently seen at 28–34 ± 4 km along the plate boundary, which corresponds to the Moho. A second strong velocity increase with depth is observed at depths of 64–66 ± 5 km, which is related to the presence of subducting slabs and anisotropic effects. We image a velocity decrease with depth at 95–135 ± 7 km, which reflects a lithosphere-asthenosphere boundary that varies in depth across the plate boundary. The deepest negative discontinuity spatially maps to the CLIP. We suggest that a deep melting depth at 135 km, associated with an elevated potential mantle temperature of 1585 ± 20°C during CLIP formation, caused a depleted and dehydrated root to the base of melting, thus thickening the lithosphere.
CLIP, Caribbean, Moho, lithosphere-asthenosphere boundary, plate-boundary, receiver functions
1525-2027
Possee, Daniel
30c7e9de-c298-469e-a9ae-c1c1caf910dc
Rychert, Catherine
70cf1e3a-58ea-455a-918a-1d570c5e53c5
Harmon, Nicholas
10d11a16-b8b0-4132-9354-652e72d8e830
Keir, Derek
5616f81f-bf1b-4678-a167-3160b5647c65
Possee, Daniel
30c7e9de-c298-469e-a9ae-c1c1caf910dc
Rychert, Catherine
70cf1e3a-58ea-455a-918a-1d570c5e53c5
Harmon, Nicholas
10d11a16-b8b0-4132-9354-652e72d8e830
Keir, Derek
5616f81f-bf1b-4678-a167-3160b5647c65

Possee, Daniel, Rychert, Catherine, Harmon, Nicholas and Keir, Derek (2021) Seismic discontinuities across the North American Caribbean plate boundary from S-to-P receiver functions. Geochemistry, Geophysics, Geosystems, 22 (7), [e2021GC009723]. (doi:10.1029/2021GC009723).

Record type: Article

Abstract

The evolution of the Caribbean plate has resulted in the formation of volcanic arcs, the Caribbean Large Igneous Province (CLIP) and micro-plates across the plate boundary zones. The northern plate boundary with the North American plate has been particularly segmented with the transition from oblique subduction to oblique collision moving from east to west. However, there are few constraints on the seismic structure of the upper mantle across the plate boundary. Here we use S-to-P receiver functions to map seismic velocity discontinuities across the plate boundary, placing constraints on crustal and lithospheric thicknesses, as well as the structures associated with subduction and collision. We image a velocity increase with depth, consistently seen at 28–34 ± 4 km along the plate boundary, which corresponds to the Moho. A second strong velocity increase with depth is observed at depths of 64–66 ± 5 km, which is related to the presence of subducting slabs and anisotropic effects. We image a velocity decrease with depth at 95–135 ± 7 km, which reflects a lithosphere-asthenosphere boundary that varies in depth across the plate boundary. The deepest negative discontinuity spatially maps to the CLIP. We suggest that a deep melting depth at 135 km, associated with an elevated potential mantle temperature of 1585 ± 20°C during CLIP formation, caused a depleted and dehydrated root to the base of melting, thus thickening the lithosphere.

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2021GC009723 - Version of Record
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Published date: July 2021
Additional Information: Funding Information: The work contained in this paper contains work conducted during a PhD study undertaken as part of the Natural Environment Research Council (NERC) Centre for Doctoral Training (CDT) in Oil & Gas (grant number NE/M00578X/1). It is 50% funded by Southampton University via their Graduate School of the National Oceanography Centre Southampton (GSNOCS) and 50% funded by NERC both of whose support is gratefully acknowledged. CAR and NH acknowledge funding from NERC (NE/M003507/1 and NE/K010654/1) and the European Research Council (GA 638665). Figures were made with the aid of the Generic Mapping Tools (Wessel & Smith, 1998 ). We thank Alan Levander and the second anonymous reviewer for their constructive comments, which have helped improve this manuscript. Funding Information: The work contained in this paper contains work conducted during a PhD study undertaken as part of the Natural Environment Research Council (NERC) Centre for Doctoral Training (CDT) in Oil & Gas (grant number NE/M00578X/1). It is 50% funded by Southampton University via their Graduate School of the National Oceanography Centre Southampton (GSNOCS) and 50% funded by NERC both of whose support is gratefully acknowledged. CAR and NH acknowledge funding from NERC (NE/M003507/1 and NE/K010654/1) and the European Research Council (GA 638665). Figures were made with the aid of the Generic Mapping Tools (Wessel & Smith,?1998). We thank Alan Levander and the second anonymous reviewer for their constructive comments, which have helped improve this manuscript. Publisher Copyright: © 2021. The Authors.
Keywords: CLIP, Caribbean, Moho, lithosphere-asthenosphere boundary, plate-boundary, receiver functions

Identifiers

Local EPrints ID: 450326
URI: http://eprints.soton.ac.uk/id/eprint/450326
ISSN: 1525-2027
PURE UUID: da014070-5375-4ae1-aa0f-1690c270d131
ORCID for Nicholas Harmon: ORCID iD orcid.org/0000-0002-0731-768X
ORCID for Derek Keir: ORCID iD orcid.org/0000-0001-8787-8446

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Date deposited: 23 Jul 2021 16:30
Last modified: 29 Nov 2022 02:43

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Contributors

Author: Daniel Possee
Author: Nicholas Harmon ORCID iD
Author: Derek Keir ORCID iD

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