The polyphased tectonic evolution of the Anegada Passage in the northern Lesser Antilles subduction zone

• Published in: Tectonics (Washington, D.C.) D.C.), 2017-05, Vol.36 (5), p.945-961
• Main Authors: Laurencin, M., Marcaillou, B., Graindorge, D., Klingelhoefer, F., Lallemand, S., Laigle, M., Lebrun, J.‐F.
• Format: Article
• Language: English
• Subjects: Anegada Passage; Basins; Bathymetric data; Convergence; Cruises; Deformation; Earth Sciences; Evolution; Faults; History; Imaging techniques; Islands; Lesser Antilles margin; Light; multichannel seismic reflection; oblique subduction zone; Obliquity; Plate convergence; Rotation; Sciences of the Universe; Seismic data; Seismological data; Shear; strain partitioning; Subduction; Subduction zones; Tectonics; Valleys
• ISSN: 0278-7407; 1944-9194
• DOI: 10.1002/2017TC004511

The influence of the highly oblique plate convergence at the northern Lesser Antilles onto the margin strain partitioning and deformation pattern, although frequently invoked, has never been clearly imaged. The Anegada Passage is a set of basins and deep valleys, regularly related to the southern boundary of the Puerto Rico‐Virgin Islands (PRVI) microplate. Despite the publications of various tectonic models mostly based on bathymetric data, the tectonic origin and deformation of this Passage remains unconstrained in the absence of deep structure imaging. During cruises Antithesis 1 and 3 (2013–2016), we recorded the first deep multichannel seismic images and new multibeam data in the northern Lesser Antilles margin segment in order to shed a new light on the structure and tectonic pattern of the Anegada Passage. We image the northeastern extent of the Anegada Passage, from the Sombrero Basin to the Lesser Antilles margin front. Our results reveal that this northeastern segment is an EW trending left‐stepping en échelon strike‐slip system that consists of the Sombrero and Malliwana pull‐apart basins, the Malliwana and Anguilla left‐lateral faults, and the NE‐SW compressional restraining bend at the Malliwana Hill. Reviewing the structure of the Anegada Passage, from the south of Puerto Rico to the Lesser Antilles margin front, reveals a polyphased tectonic history. The Anegada Passage is formed by a NW‐SE extension, possibly related to the rotation or escape of PRVI block due to collision of the Bahamas Bank. Currently, it is deformed by an active WNW‐ESE strike‐slip deformation associated to the shear component of the strain partitioning resulting from the subduction obliquity. Key Points New bathymetric and seismic data highlight the deformation pattern of the northern Lesser Antilles active margin The Anegada Passage is a NE‐SW trending past structure which is opened by NW‐SE extension due to the collision of the Bahamas Bank Strain partitioning, related to the plate convergence obliquity, currently deforms the Anegada Passage by a WNW‐ESE shear strain.