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Variation in Upper Plate Crustal and Lithospheric Mantle Structure in the Greater and Lesser Antilles from Ambient Noise Tomography
  • +19
  • David Schlaphorst,
  • Nicholas Harmon,
  • John-Michael Kendall,
  • Catherine A. Rychert,
  • Jenny S Collier,
  • Andreas Rietbrock,
  • Saskia Goes,
  • Robert William Allen,
  • Lidong Bie,
  • Jon D Blundy,
  • Ben Chichester,
  • George Cooper,
  • Richard Gareth Davy,
  • Tim J Henstock,
  • Stephen P. Hicks,
  • Colin G. Macpherson,
  • Ben Maunder,
  • Julie Prytulak,
  • Jeroen van Hunen,
  • Jamie J Wilkinson,
  • Marjorie Wilson,
  • Jon P Davidson
David Schlaphorst
Instituto Dom Luiz (IDL), Faculdade de Ciências, Universidade de Lisboa

Corresponding Author:[email protected]

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Nicholas Harmon
University of Southampton
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John-Michael Kendall
University of Oxford
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Catherine A. Rychert
University of Southampton
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Jenny S Collier
Imperial College London
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Andreas Rietbrock
University of Karlsruhe
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Saskia Goes
Imperial College London
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Robert William Allen
Imperial College, London
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Lidong Bie
Karlsruhe Insitute of Technology
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Jon D Blundy
Oxford University
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Ben Chichester
University of Southampton
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George Cooper
Cardiff University
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Richard Gareth Davy
Imperial College London
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Tim J Henstock
University of Southampton
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Stephen P. Hicks
Imperial College London
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Colin G. Macpherson
University of Durham
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Ben Maunder
Imperial College London
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Julie Prytulak
University of Durham
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Jeroen van Hunen
Durham University, UK
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Jamie J Wilkinson
Imperial College London
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Marjorie Wilson
University of Leeds
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Jon P Davidson
Durham University
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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 VoiLA experiment to map crustal and upper mantle shear-wave velocity of the eastern Greater Antilles and the Lesser Antilles Arc. We find sediment thickness, based on the depth to the 2.0 km/s contour in the Grenada and Tobago basins up to 15 km in the south, with 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.