Gravity modeling of the Muertos Trough and tectonic implications (north-eastern Caribbean)
Gravity modeling of the Muertos Trough and tectonic implications (north-eastern Caribbean)
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Muertos 海槽的重力模拟及其构造影响（加勒比海东北部）
DOI：
10.1007/s11001-010-9107-8
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发表时间：
2010
期刊：
影响因子：
--
通讯作者：
M. Catalán Morollón
中科院分区：
文献类型：
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作者：
J. Granja Bruña;A. Muñoz;U. T. ten Brink;A. Carbó;P. Llanes Estrada;J. Martín;D. Córdoba;M. Catalán Morollón
加勒比海东北部的Muertos海槽已被解释为地震活动的俯冲带，从而推断可能的反转俯冲极性。然而，地震活动的分布是非常分散的，使板块几何形状的定义变得困难。此外，在上地壳和沙箱运动学模拟中观察到的压缩变形特征并不一定表明俯冲过程。我们使用重力模型测试了加勒比板块内部在大安的列斯群岛东部岛弧下的俯冲假设。重力模型模拟俯冲过程产生的岛弧下的区域质量赤字的几何形状和深度的俯冲板在模型中使用的独立。这种质量赤字的结果下沉的密度较低的加勒比板块岩石圈地幔下取代更致密的地幔物质，并表明，没有一个俯冲加勒比海高原岛弧下。从地质学上讲，更现实的重力模型可以解释在上地壳中观察到的南北缩短现象，它需要一个逆冲的加勒比板块，从变形前缘向北延伸至少60公里，逆冲角度从8°逐渐增加到30°，最深处在岛坡之下22公里。Muertos边缘的这种新构造模型被定义为弧后逆冲，将有助于评估该地区的地震和海啸危险。重力模型的使用为未来在Muertos边缘进行广角地震勘探提供了目标。
The Muertos Trough in the northeast Caribbean has been interpreted as a subduction zone from seismicity, leading to infer a possible reversal subduction polarity. However, the distribution of the seismicity is very diffuse and makes definition of the plate geometry difficult. In addition, the compressive deformational features observed in the upper crust and sandbox kinematic modeling do not necessarily suggest a subduction process. We tested the hypothesized subduction of the Caribbean plate’s interior beneath the eastern Greater Antilles island arc using gravity modeling. Gravity models simulating a subduction process yield a regional mass deficit beneath the island arc independently of the geometry and depth of the subducted slab used in the models. This mass deficit results from sinking of the less dense Caribbean slab beneath the lithospheric mantle replacing denser mantle materials and suggests that there is not a subducted Caribbean plateau beneath the island arc. The geologically more realistic gravity model which would explain the N–S shortening observed in the upper crust requires an overthrusted Caribbean slab extending at least 60 km northward from the deformation front, a progressive increase in the thrusting angle from 8° to 30° reaching a maximum depth of 22 km beneath the insular slope. This new tectonic model for the Muertos Margin, defined as a retroarc thrusting, will help to assess the seismic and tsunami hazard in the region. The use of gravity modeling has provided targets for future wide-angle seismic surveys in the Muertos Margin.