Seismic Discontinuities Across the North American Caribbean Plate Boundary From S‐to‐P Receiver Functions

Daniel Possee,Catherine Rychert,Derek Keir,Nicholas Harmon

doi:10.1029/2021gc009723

Abstract

AbstractThe evolution of the Caribbean plate has resulted in the formation of volcanic arcs, the Caribbean Large Igneous Province (CLIP) and micro‐plates across the plate boundary zones. The northern plate boundary with the North American plate has been particularly segmented with the transition from oblique subduction to oblique collision moving from east to west. However, there are few constraints on the seismic structure of the upper mantle across the plate boundary. Here we use S‐to‐P receiver functions to map seismic velocity discontinuities across the plate boundary, placing constraints on crustal and lithospheric thicknesses, as well as the structures associated with subduction and collision. We image a velocity increase with depth, consistently seen at 28–34 ± 4 km along the plate boundary, which corresponds to the Moho. A second strong velocity increase with depth is observed at depths of 64–66 ± 5 km, which is related to the presence of subducting slabs and anisotropic effects. We image a velocity decrease with depth at 95–135 ± 7 km, which reflects a lithosphere‐asthenosphere boundary that varies in depth across the plate boundary. The deepest negative discontinuity spatially maps to the CLIP. We suggest that a deep melting depth at 135 km, associated with an elevated potential mantle temperature of 1585 ± 20°C during CLIP formation, caused a depleted and dehydrated root to the base of melting, thus thickening the lithosphere.

Highlights

Key events during the evolution of the Caribbean plate, such as the eruption of the Caribbean Large Igneous Province (CLIP) and collision of the Great Arc of the Caribbean (GAC) with the Bahamas platform, have dramatically influenced the resulting structure and kinematics of the North American-Caribbean plate boundary
Much of the northern Caribbean plate boundary is composed of the GAC and CLIP terranes (Iturralde-Vinent et al, 2016; Mann et al, 1991; Mauffret & Leroy, 1997), which extend from Puerto Rico through to Jamaica and Cuba (Figure 1)
The increase in thickness has been attributed to the collision of the GAC with the Bahamas platform, with a purely volcanic arc crust in the south, which has been emplaced over parts of the Bahamas platform in the north to produce the thicker crust during the collision (Arango-Arias et al, 2014)

Summary

Introduction

Key events during the evolution of the Caribbean plate, such as the eruption of the Caribbean Large Igneous Province (CLIP) and collision of the Great Arc of the Caribbean (GAC) with the Bahamas platform, have dramatically influenced the resulting structure and kinematics of the North American-Caribbean plate boundary. While there are many tectonic reconstructions of the lithospheric evolution of the Caribbean plate Much of the northern Caribbean plate boundary is composed of the GAC and CLIP terranes (Iturralde-Vinent et al, 2016; Mann et al, 1991; Mauffret & Leroy, 1997), which extend from Puerto Rico through to Jamaica and Cuba (Figure 1). It represents a key location to study the link between the present day lithospheric structure and the evolutionary tectonic and magmatic events that have shaped the Caribbean plate

Methods

Results

Discussion

Conclusion