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Long-term and long-distance deformation in submarine volcanoclastic sediments: Coupling of hydrogeology and debris avalanche emplacement off W Martinique Island
Basin Research ( IF 2.8 ) Pub Date : 2021-02-07 , DOI: 10.1111/bre.12553 J. Llopart 1, 2 , S. Lafuerza 2 , A Le Friant 1 , R. Urgeles 3 , L. Watremez 4
Basin Research ( IF 2.8 ) Pub Date : 2021-02-07 , DOI: 10.1111/bre.12553 J. Llopart 1, 2 , S. Lafuerza 2 , A Le Friant 1 , R. Urgeles 3 , L. Watremez 4
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West off Martinique (Lesser Antilles), the Grenada Basin submarine sediments were affected by the emplacement of Debris Avalanche Deposits (DAD). Montagne Pelée Volcano has experienced three major flank collapses during the last ca. 127 kyrs, resulting in a cumulated volume of up to 300 km3 offshore. Using a combination of geophysical and geotechnical data, we investigate the effect of these debris avalanches emplacements on the basin hydrogeology and their relationship with the observed sediment deformation in the seismic and coring data. The geotechnical test carried on IODP-340 cores samples reveal four sediment types within the basin with distinctive mechanical and hydraulic properties: proximal volcanoclastics, distal volcanoclastics, hemipelagic and ash-rich sediments. These results, together with margin stratigraphic models obtained from seismic reflection data, were used as inputs for the numerical finite-element model. This model shows that the coupling of the sediment properties with the mid- to low-sedimentation rates results in the development of low overpressures prior to the first flank collapse at 127 ka. However, the emplacement of the first two DADs, between 127 and 36 ka, developed high overpressures ratios (λ* > 0.9) in the easternmost part of the Grenada Basin. According to the model, the sudden compaction of the pre-existing sediments due to the DADs load created fluid flow velocities up to 7 times higher than the hydraulic conductivities, which would have thus reduced the sediment bearing capacities and shear strength, favouring their mobilization and deformation. From 127 to 36 ka, the sea-floor sediments suffered a long-term deformation driven by the combination of the weight of the emplaced material and the persistence of high overpressure ratios through time. This deformation propagated tens of kilometres away from the DAD’s emplacement and it is possible that still continues today due to the persistence of low overpressure ratios. This long-term and long-distance deformation and persisted overpressures are a key factor to take into account in the framework of a geohazards evaluation in areas recurrently affected by earthquakes and volcanic flank collapses.
中文翻译：
海底火山碎屑沉积物中的长期和长距离变形：水文地质与马提尼克岛附近碎屑雪崩侵位的耦合
在马提尼克岛西部（小安的列斯群岛），格林纳达盆地海底沉积物受到碎片雪崩沉积物 (DAD) 就位的影响。Montagne Pelée 火山在过去的大约 3 年间经历了三次主要的侧翼坍塌。127 kyrs，累积体积可达 300 km 3离岸。我们结合使用地球物理和岩土工程数据，研究了这些碎屑雪崩对盆地水文地质学的影响，以及它们与地震和取心数据中观测到的沉积物变形的关系。对 IODP-340 岩心样本进行的岩土工程测试揭示了盆地内具有独特机械和水力特性的四种沉积物类型：近端火山碎屑、远端火山碎屑、半远洋和富含灰烬的沉积物。这些结果与从地震反射数据中获得的边缘地层模型一起用作数值有限元模型的输入。该模型表明，沉积物性质与中低沉积速率的耦合导致在 127 ka 的第一次侧翼坍塌之前形成低超压。然而，* > 0.9) 在格林纳达盆地的最东部。根据该模型，由于 DAD 载荷导致预先存在的沉积物突然压实，产生的流体流速高达水力传导率的 7 倍，从而降低了沉积物的承载能力和剪切强度，有利于它们的流动和流动。形变。从 127 到 36 ka，海底沉积物遭受了长期变形，这是由于被安置物质的重量和高超压比随时间持续存在的共同驱动的。这种变形从 DAD 的位置传播了数十公里，由于低超压比的持续存在，这种变形今天可能仍在继续。
更新日期：2021-02-07
中文翻译：
海底火山碎屑沉积物中的长期和长距离变形：水文地质与马提尼克岛附近碎屑雪崩侵位的耦合
在马提尼克岛西部（小安的列斯群岛），格林纳达盆地海底沉积物受到碎片雪崩沉积物 (DAD) 就位的影响。Montagne Pelée 火山在过去的大约 3 年间经历了三次主要的侧翼坍塌。127 kyrs，累积体积可达 300 km 3离岸。我们结合使用地球物理和岩土工程数据，研究了这些碎屑雪崩对盆地水文地质学的影响，以及它们与地震和取心数据中观测到的沉积物变形的关系。对 IODP-340 岩心样本进行的岩土工程测试揭示了盆地内具有独特机械和水力特性的四种沉积物类型：近端火山碎屑、远端火山碎屑、半远洋和富含灰烬的沉积物。这些结果与从地震反射数据中获得的边缘地层模型一起用作数值有限元模型的输入。该模型表明，沉积物性质与中低沉积速率的耦合导致在 127 ka 的第一次侧翼坍塌之前形成低超压。然而，* > 0.9) 在格林纳达盆地的最东部。根据该模型，由于 DAD 载荷导致预先存在的沉积物突然压实，产生的流体流速高达水力传导率的 7 倍，从而降低了沉积物的承载能力和剪切强度，有利于它们的流动和流动。形变。从 127 到 36 ka，海底沉积物遭受了长期变形，这是由于被安置物质的重量和高超压比随时间持续存在的共同驱动的。这种变形从 DAD 的位置传播了数十公里，由于低超压比的持续存在，这种变形今天可能仍在继续。
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