Atlantic subduction system
Schematic tectonic reconstruction of the Lesser Antilles SZI event (modified from van Benthem et al., 2013 and Boschman et al., 2014). Subduction of the North and South America plates beneath the Caribbean plate was probably already active earlier on. At 58-39 Ma, subduction jumped eastwards, creating the new Lesser Antilles SZ. Shown are the new subduction zone (pink line), other active (solid purple lines) and inactive (dashed purple lines) subduction zones, and transform faults (red dashed lines).
The Lesser Antilles SZI event that formed the present-day Lesser Antilles subduction zone likely occurred between 59-38 Ma (Boschmann et al., 2014), with the North and South American plates subducting below the Caribbean plate. However, there is a debate on the nature of this event, which also represents the transition from the Greater Caribbean Arc to the Lesser Antilles subduction zone. The break in the slab, revealed by seismic tomography (van Benthem et al., 2013), along with the age gap between the Aves Ridge and the Lesser Antilles Arc and the start of the formation of the Barbados Accretionary Prism (Boschman 2014) suggests episodic subduction. Other interpretations consider continuous subduction during the narrowing of the arc and suggest that the arc has jumped 50-250 km from the Avis ridge to the Lesser-Antilles arc during continuous subduction roll-back and the consequent opening of the Grenada and Tobago basins (together) as a forearc basin (e.g., Aitken et al., 2011). Due to the widening forearc, the Avis ridge became inactive. In this scenario, the SZI event of the Lesser Antilles is the same as that of the Greater Caribbean arc, which might have happened sometimes between 120 to 88 Ma. This earlier event is not considered here any further.
The Lesser Antilles SZI event might be an episodic event that followed from a previously active, but subsequently extinct, subduction zone; it is suggested that the active arc from the Aves ridge transitioned to, and formed, the Lesser Antilles arc during the mentioned time span (Boschmann et al., 2014).
Ages of arc volcanism (K–Ar) in the Lesser Antilles Arc range from 38 Ma to present (Briden et al., 1979), while in the Aves ridge, volcanic rocks age between 88 to 59 Myr (Neill et al., 2011). The Barbados prism, forming the accretionary prism of the Lesser Antilles subduction zone, was building up since the Early Eocene (Speed and Larue, 1982).
In the model of Müller et al. (2016), the Lesser Antilles SZI event occurs at 53 Ma. The Lesser Antilles subduction zone nucleated mostly parallel to and generally between 150 and 300 km of a pre-existing subduction zone (unnamed in the model), along which the South American plate subducted beneath the Caribbean plate (with the same polarity as the Lesser Antilles subduction zone). The Caribbean plate exhibits a rather minor change in its plate motion at 55 Ma, but otherwise, there are no significant plate reorganisations associated with the Lesser Antilles SZI event.
In the Atlas of the Underworld (van der Meer et al., 2018), the Lesser Antilles is connected to the Caribbean slab, which is imaged with P-wave tomography from below the surface to 750 km depth. A vote map cross-section through the Caribbean arc at 16º latitude shows a consistent fast (P- and S-wave) anomaly between 200 and 600 km depth. This anomaly cannot be differentiated from a lower-mantle anomaly towards the south.
Seismic tomography VoteMap (Shephard et al., 2017) analysis of the Lesser Antilles SZI event.
Lesser Antilles SZI event as reconstructed in the model of Müller et al. (2016). Pink dashed (solid with teeth) line shows the Lesser Antilles trench 1 Myr before (at) SZI time in the model. Purple (red) lines show segments of neighbouring subduction zones (ridges and transforms) that lie within some radius of the Lesser Antilles trench (pink line); the brightness of the colours reflects 3 different distance thresholds of 250, 500 and 1000 km.
Aitken, T., Mann, P., Escalona, A., & Christeson, G. L. (2011). Evolution of the Grenada and Tobago basins and implications for arc migration. Marine and Petroleum Geology, 28(1), 235-258.
Boschman, L. M., van Hinsbergen, D. J., Torsvik, T. H., Spakman, W., & Pindell, J. L. (2014). Kinematic reconstruction of the Caribbean region since the Early Jurassic. Earth-Science Reviews, 138, 102-136.
Briden, J. C., Rex, D. C., Faller, A. M., & Tomblin, J. F. (1979). K-Ar geochronology and palaeomagnetism of volcanic rocks in the Lesser Antilles island arc. Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences, 291(1383), 485-528.
Müller, R. D., Seton, M., Zahirovic, S., Williams, S. E., Matthews, K. J., Wright, N. M., Shephard, G. E., Maloney, K. T., Barnett-Morre, N., Hosseinpour, M., Bower, D. J., Cannon, J. (2016). Ocean Basin Evolution and Global-Scale Plate Reorganization Events Since Pangea Breakup. Annual Review of Earth and Planetary Sciences, 44, 107-138.
Neill, I., Kerr, A. C., Hastie, A. R., Stanek, K. P., & Millar, I. L. (2011). Origin of the Aves Ridge and Dutch–Venezuelan Antilles: interaction of the Cretaceous ‘Great Arc'and Caribbean–Colombian Oceanic Plateau?. Journal of the Geological Society, 168(2), 333-348.
Shephard, G.E., Matthews, K.J., Hosseini, K., Domeier, M. (2017). On the consistency of seismically imaged lower mantle slabs. Scientific Reports 7.
Speed, R. C., & Larue, D. K. (1982). Barbados: architecture and implications for accretion. Journal of Geophysical Research: Solid Earth, 87(B5), 3633-3643.
van Benthem, S., Govers, R., Spakman, W., & Wortel, R. (2013). Tectonic evolution and mantle structure of the Caribbean. Journal of Geophysical Research: Solid Earth, 118(6), 3019-3036.
van der Meer, D. G., van Hinsbergen, D. J., & Spakman, W. (2018). Atlas of the underworld: Slab remnants in the mantle, their sinking history, and a new outlook on lower mantle viscosity. Tectonophysics, 723, 309-448.