Tectonic evolution and mantle structure of the Caribbean

Abstract

We investigate whether predictions of mantle structure from tectonic reconstructions are in agreement with a detailed tomographic image of seismic P wave velocity structure under the Caribbean region. In the upper mantle, positive seismic anomalies are imaged under the Lesser Antilles and Puerto Rico. These anomalies are interpreted as remnants of Atlantic lithosphere subduction and confirm tectonic reconstructions that suggest at least 1100 km of convergence at the Lesser Antilles island arc during the past ~45 Myr. The imaged Lesser Antilles slab consists of a northern and southern anomaly, separated by a low‐velocity anomaly across most of the upper mantle, which we interpret as the subducted North America‐South America plate boundary. The southern edge of the imaged Lesser Antilles slab agrees with vertical tearing of South America lithosphere. The northern Lesser Antilles slab is continuous with the Puerto Rico slab along the northeastern plate boundary. This results in an amphitheater‐shaped slab, and it is interpreted as westward subducting North America lithosphere that remained attached to the surface along the northeastern boundary of the Caribbean plate. At the Muertos Trough, however, material is imaged until a depth of only 100 km, suggesting a small amount of subduction. The location and length of the imaged South Caribbean slab agrees with proposed subduction of Caribbean lithosphere under the northern South America plate. An anomaly related to proposed Oligocene subduction at the Nicaragua rise is absent in the tomographic model. Beneath Panama, a subduction window exists across the upper mantle, which is related to the cessation of subduction of the Nazca plate under Panama since 9.5 Ma and possibly the preceding subduction of the extinct Cocos‐Nazca spreading center. In the lower mantle, two large anomaly patterns are imaged. The westernmost anomaly agrees with the subduction of Farallon lithosphere. The second lower mantle anomaly is found east of the Farallon anomaly and is interpreted as a remnant of the late Mesozoic subduction of North and South America oceanic lithosphere at the Greater Antilles, Aves ridge, and Leeward Antilles. The imaged mantle structure does not allow us to discriminate between an “Intra‐Americas origin” and a “Pacific origin” of the Caribbean plate.

Mantle structure and tectonic history of SE Asia

“…Several authors (e.g. Chertova et al, 2014;Schellart and Spakman, 2012;Schellart et al, 2009;van Benthem et al, 2013; have used model UU-P07 in studies of regional mantle structure. It is the successor to the BSE model of Bijwaard et al (1998) and is based on a similar treatment of travel-time data, mantle cell division and inversion approach.…”

The role of passive margins on the evolution of Subduction‐Transform Edge Propagators (STEPs)

“…At the south Lesser Antilles subduction zone, seismic tomographic images of the upper mantle show an edge along the south Lesser Antilles slab, that roughly aligns with the STEP fault (El Pilar fault zone) between the surface plates [ van Benthem et al ., ]. This STEP fault is located along the margin of the continental South American lithosphere (Figure [ Govers and Wortel , ; van Benthem et al ., ]). We suspect that the coincidence of the STEP fault and the passive margin is a consequence of rupturing along the mechanical strength contrast there.…”

“…The brown region indicates the diffuse boundary between the North and South American plates (after van Benthem et al . []). The grey dashed line indicates the end of the South American passive margin.…”

The effect of obliquity on temperature in subduction zones: insights from 3D numerical modeling

“…Such variations of slab shape are observed below the strait of Gibraltar (Bezada et al, 2013), below Turkey (Biryol et al, 2011), below Japan (Zhao et al, 2012Liu and Zhao, 2016), below the eastern Caribbean plate (Van Benthem et al, 2013) and in many other subduction zones, and are summarized in the SLAB1.0 model (Hayes et al, 2012). These complicated pictures of slab geometry allow us to make simple tests to study the possible effects of geometry on the mantle flow and on temperature in subduction zones, and especially at the subduction 20 interface.…”