We explore the shear-wave lithospheric velocity structure of the Eastern Caribbean and Northern Venezuela using ambient noise tomography with stations deployed around the study area. We construct cross-correlation functions from continuous seismic records, and measure phase velocities of fundamental-mode Rayleigh waves. These velocities are further projected onto 0.6°x0.6° phase velocity grids for each period between 5 s and 50 s. The pseudo-dispersion curve at each grid point is inverted for 1D shear velocity profiles by using a Markov Chain Monte Carlo scheme. The interpolated 3D velocity model shows that the mean shear velocity of the Eastern Caribbean lithospheric mantle is lower than the global average, which is in agreement with values reported in other large igneous provinces. We interpret that low velocities in the lithospheric keel are associated with an anomalous composition and/or an elevated thermal state; this gives the Caribbean plate a high buoyancy that determines the subduction polarities in the region. The results also indicate that: (a) the mantle beneath Northern Venezuela retains compositional anomalies related to extension processes of different ages; (b) the overriding of the Caribbean plate by the Great Antilles arc seems to be much slower than previously suggested; and (c) the localized volcanism in the center of the Lesser Antilles arc is related to asthenospheric flow through the tear induced on the subducted slab by major strike-slip faults.

我们使用环境噪声层析成像技术以及在研究区域周围部署的站点，探索了东加勒比海和委内瑞拉北部的横波岩石圈速度结构。我们从连续的地震记录中构造互相关函数，并测量基模瑞利波的相速度。对于5 s至50 s之间的每个周期，这些速度还被投影到0.6°x0.6°相速度网格上。通过使用马尔可夫链蒙特卡洛方法，针对一维剪切速度剖面，将每个网格点的拟色散曲线反转。插值的3D速度模型显示，东加勒比海岩石圈地幔的平均剪切速度低于全球平均水平，这与其他大火成岩省份报告的值一致。我们解释说，岩石圈龙骨中的低速度与异常成分和/或高温状态有关。这使加勒比海板块具有很高的浮力，从而决定了该地区的俯冲极性。结果还表明：（a）委内瑞拉北部下方的地幔保留了与不同年龄的延伸过程有关的成分异常；（b）大安的列斯群岛对加勒比海板块的覆盖似乎比以前建议的要慢得多；（c）小安的列斯群岛弧中心的局部火山作用与软流圈流经主要走滑断层引起的俯冲板片上的裂隙有关。这使加勒比海板块具有很高的浮力，从而决定了该地区的俯冲极性。结果还表明：（a）委内瑞拉北部下方的地幔保留了与不同年龄的延伸过程有关的成分异常；（b）大安的列斯群岛对加勒比海板块的覆盖似乎比以前建议的要慢得多；（c）小安的列斯群岛弧中心的局部火山作用与软流圈流经主要走滑断层引起的俯冲板片上的裂隙有关。这使加勒比海板块具有很高的浮力，从而决定了该地区的俯冲极性。结果还表明：（a）委内瑞拉北部下方的地幔保留了与不同年龄的延伸过程有关的成分异常；（b）大安的列斯群岛对加勒比海板块的覆盖似乎比以前建议的要慢得多；（c）小安的列斯群岛弧中心的局部火山作用与软流圈流经主要走滑断层引起的俯冲板片上的裂隙有关。