Caribbean Slab Segmentation Beneath Northwest South America Revealed by 3‐D Finite Frequency Teleseismic P‐Wave Tomography

Abstract

The Caribbean plate subducts beneath northwest South America at a shallow angle due to a large igneous province that added up to 12 km of buoyant crust. The overriding plate lacks volcanism and exhibits Laramide‐style uplifts over 500 km from the trench. Here, we illuminate the subduction structures through finite frequency teleseismic P‐wave tomography and connect those structures to the Laramide‐style deformation on the overriding plate. We use a new data set collected from the Caribbean‐Mérida Andes seismic experiment comprised of 65 temporary broadband stations integrated with permanent stations from the Colombian and Venezuelan national networks. We identify three segments of subducting Caribbean plate with one segment completely detached from the surface. The timing of the detachment aligns with other regional events, including the uplift of the Mérida Andes, about 10 Ma. Slab buoyancy post‐detachment likely resulted in recoupling with the overriding plate, reactivation of Jurassic‐aged rift structures and subsequent uplift of the Mérida Andes. Mantle counterflow over the broken segment induced by rollback of the attached slab likely contributed to the uplift of the Mérida Andes. We conclude that the northern limit of subduction lies south of the Oca‐Ancón fault, though the fault itself may be the surface expression of the boundary. The southern limit of subduction lies south of our study area.

Kinematics and Convergent Tectonics of the Northwestern South American Plate during the Cenozoic.

“…In agreement with previous studies, our interpretation confirms that most of the Caribbean plate corresponds to a flat-slab (e.g. Cornthwaite et al, 2021;Sun et al, 2022) that decreases its dip towards the north (Figs.8,13). This shallow geometry is supported by a continuous northward trend of intermediatedepth seismicity (WBZ) at about 73°W (Fig.…”

“…Based on seismological and tomography interpretations, several authors have proposed that the current geometry of the Caribbean slab is characterized by shallow subduction beneath northern Colombia and Venezuela (e.g. Taboada et al, 2000;Bezada et al, 2010;Syracuse et al, 2016;Cornthwaite et al, 2021;Sun et al, 2022). 128 Fig.…”

Regional Geophysics of the Caribbean and Northern South America: Implications for Tectonics

“…Although there is no seismic activity at the trench, the hypocenters exist to the southeast and a Benioff zone can be traced to a depth of 175 km. This confirms, as reported in previous papers (Bernal-Olaya et al, 2015;Cornthwaite et al, 2021;Mora et al, 2017;M. Sun et al, 2022;van Benthem et al, 2013), the subduction of the Caribbean plate beneath northern South America and implies that part of the plate has been consumed at this active margin.…”

“…The deep lithospheric and mantle structure of South America and the Caribbean has been investigated using seismic tomography (Bijwaard et al., 1998; Braszus et al., 2021; Celli et al., 2020; Cornthwaite et al., 2021; Obayashi et al., 2013; Sallarès et al., 2000; Schaeffer & Lebedev, 2013; Simmons et al., 2012; M. Sun et al., 2022; van Benthem et al., 2013; Zhu et al., 2020). A recent teleseismic P‐wave tomography model (DETOX‐P1) has brought the geometries of subducted slabs under South America into sharper focus through the use of regional South American data (Hosseini et al., 2020; Mohammadzaheri et al., 2021).…”

“…The deep lithospheric and mantle structure of South America and the Caribbean has been investigated using seismic tomography (Bijwaard et al, 1998;Braszus et al, 2021;Celli et al, 2020;Cornthwaite et al, 2021;Obayashi et al, 2013;Sallarès et al, 2000;Schaeffer & Lebedev, 2013;Simmons et al, 2012;M. Sun et al, 2022;van Benthem et al, 2013;Zhu et al, 2020).…”