Imaging subduction zone processes along the Lesser Antilles using a broadband ocean bottom seismometer network: The VoiLA experiment

Volcanoes, earthquakes and natural resources along the margins of the Caribbean plate have been shaped by a history of subduction. In this presentation I will provide an overview how a dense deployment of Broadband Ocean Bottom Seismometer (BOBS) helped us to investigate several fundamental processes caused by the subduction of lithospheric crust and mantle through the upper mantel down to the mantle transition zone (MTZ). Using teleseismic tomography and plate reconstruction techniques we unraveled the tectonic history of the Caribbean plate showing clear evidence of a slab window and tear along the subducted Proto-Caribbean ridge, which also hosted one of the largest intermediate depth earthquakes in the region. Using local earthquake tomography, we developed a new slab model for the region and combining travel time and attenuation tomography we were able to identify melt ponds under the upper plate. We also found that serpentine most likely residing along major fracture zones is the dominant supplier of subducted water in the central arc of the Caribbean. Finally, by using P-to-S receiver functions to image the slab and the mantle transition zone beneath the Lesser Antilles we find that the slab flows directly though the mantle transition zone exhibiting super-deep (>700 km) discontinuities caused by a large basalt-rich chemical anomaly. All our findings point in the direction that the tectonic history of the subducting lithospheric crust and mantle has a strong influence on the observed geodynamic processes we image with geophysical techniques in subduction zone settings.