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Variation in Upper Plate Crustal and Lithospheric Mantle Structure in the Greater and Lesser Antilles from Ambient Noise Tomography

Schlaphorst, D. and Harmon, N. and Kendall, J.M. and Rychert, C.A. and Collier, J. and Rietbrock, A. and Goes, S. and Allen, R.W. and Bie, L. and Blundy, J.D. and Chichester, B. and Cooper, G.F. and Davidson, J.P. and Davy, R.G. and Henstock, T.J. and Hicks, S.P. and Macpherson, C.G. and Maunder, B. and Prytulak, J. and Hunen, J. and Wilkinson, J.J. (2021) 'Variation in Upper Plate Crustal and Lithospheric Mantle Structure in the Greater and Lesser Antilles from Ambient Noise Tomography.', Geochemistry, Geophysics, Geosystems, 22 (7). e2021GC009800.

Abstract

The crust and upper mantle structure of the Greater and Lesser Antilles Arc provides insights into key subduction zone processes in a unique region of slow convergence of old slow-spreading oceanic lithosphere. We use ambient noise tomography gathered from island broadband seismic stations and the temporary ocean bottom seismometer network installed as part of the Volatile Recycling in the Lesser Antilles experiment to map crustal and upper mantle shear-wave velocity of the eastern Greater Antilles and the Lesser Antilles Arc. Taking the depth to the 2.0 km/s contour as a proxy, we find sediment thickness up to 15 km in the south in the Grenada and Tobago basins and thinner sediments near the arc and to the north. We observe thicker crust, based on the depth to the 4.0 km/s velocity contour, beneath the arc platforms with the greatest crustal thickness of around 30 km, likely related to crustal addition from arc volcanism through time. There are distinct low velocity zones (4.2–4.4 km/s) in the mantle wedge (30–50 km depth), beneath the Mona Passage, Guadeloupe-Martinique, and the Grenadines. The Mona passage mantle anomaly may be related to ongoing extension there, while the Guadeloupe-Martinique and Grenadine anomalies are likely related to fluid flux, upwelling, and/or partial melt related to nearby slab features. The location of the Guadeloupe-Martinique anomaly is slightly to the south of the obliquely subducted fracture zones. This feature could be explained by either three-dimensional mantle flow, a gap in the slab, variable slab hydration, and/or melt dynamics including ponding and interactions with the upper plate.

Item Type:Article
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Status:Peer-reviewed
Publisher Web site:https://doi.org/10.1029/2021GC009800
Publisher statement:Accepted for publication in Geochemistry, Geophysics, Geosystems. Copyright 2021, American Geophysical Union. Further reproduction or electronic distribution is not permitted
Date accepted:21 June 2021
Date deposited:08 July 2021
Date of first online publication:25 June 2021
Date first made open access:08 July 2021

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