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首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >Geodynamic evolution of the lithosphere and upper mantle beneath the Alboran region of the western Mediterranean: Constraints from travel time tomography
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Geodynamic evolution of the lithosphere and upper mantle beneath the Alboran region of the western Mediterranean: Constraints from travel time tomography

机译：地中海西部阿尔伯兰地区下方岩石圈和上地幔的地球动力学演化：旅行时间层析成像的限制

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A number of different geodynamic models have been proposed to explain the extension that occurred during the Miocene in the Alboran Sea region of the western Mediterranean despite the continued convergence and shortening of northern Africa and southern Iberia. In an effort to provide additional geophysical constraints on these models, we performed a local, regional, and teleseismic tomographic travel time inversion for the lithospheric and upper mantle velocity structure and earthquake locations beneath the Alboran region in an area of 800 x 800 km(2). We picked P and S arrival times from digital and analog seismograms recorded by 96 seismic stations in Morocco and Spain between 1989 and 1996 and combined them with arrivals carefully selected from local and global catalogs (1964-1998) to generate a starting data set containing over 100,000 arrival times. Our results indicate that a N-S line of intermediate-depth earthquakes extending from crustal depths significantly inland from the southern Iberian coast to depths of over 100 km beneath the center of the Alboran Sea coincides with a W to E transition from high to low velocities imaged in the uppermost mantle. A high-velocity body, striking approximately NE-SW, is imaged to dip southeastwards from lithospheric depths beneath the low-velocity region to depths of similar to 350 km. Between 350 and 500 km the imaged velocity anomalies become more diffuse. However, pronounced high-velocity anomalies are again imaged at 600 km near an isolated cluster of deep earthquakes. In addition to standard tomographic methods of error assessment, the effects of systematic and random errors were assessed using block shifting and bootstrap resampling techniques, respectively. We interpret the upper mantle high-velocity anomalies as regions of colder mantle that originate from lithospheric depths. These observations, when combined with results from other studies, suggest that delamination of a continental lithosphere played an important role in the Neogene and Quaternary evolution of the region. [References: 80]
机译：已经提出了许多不同的地球动力学模型来解释地中海北部阿尔博兰海地区中新世发生的扩张，尽管北部非洲和伊比利亚南部持续不断的收敛和缩短。为了对这些模型提供额外的地球物理约束，我们对800 x 800 km（2）的Alboran地区以下的岩石圈和上地幔速度结构以及地震位置进行了局部，区域和远震层析成像时间反演）。我们从1989年至1996年间在摩洛哥和西班牙的96个地震台站记录的数字和模拟地震图中选择了P和S的到达时间，并将它们与从本地和全球目录（1964-1998）中精心选择的到达相结合，生成了包含100,000次到达。我们的结果表明，一条中深度地震的NS线从伊比利亚南部沿海明显内陆的地壳深度延伸到Alboran海中心以下100 km以上的深度，与从高速到低速的W向E过渡相吻合。最上层的地幔。撞击大约NE-SW的高速物体被成像为从低速区域下方的岩石圈深度向东南倾斜至大约350 km的深度。在350至500 km之间，成像的速度异常变得更加分散。但是，在孤立的深部地震群附近600 km处再次出现了明显的高速异常。除了标准的层析成像错误评估方法外，还分别使用块移位和自举重采样技术评估了系统错误和随机错误的影响。我们将上地幔高速异常解释为源自岩石圈深度的较冷地幔区域。这些观察结果与其他研究的结果相结合，表明大陆岩石圈的分层在该地区的新近纪和第四纪演化中起着重要作用。 [参考：80]

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