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首页> 外文期刊>Geochemistry, geophysics, geosystems >Submarine record of volcanic island construction and collapse in the Lesser Antilles arc: First scientific drilling of submarine volcanic island landslides by IODP Expedition 340
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Submarine record of volcanic island construction and collapse in the Lesser Antilles arc: First scientific drilling of submarine volcanic island landslides by IODP Expedition 340

机译：小安的列斯群岛火山岛建造和坍塌的海底记录：IODP Expedition 340首次对海底火山岛滑坡进行科学钻探

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IODP Expedition 340 successfully drilled a series of sites offshore Montserrat, Martinique and Dominica in the Lesser Antilles from March to April 2012. These are among the few drill sites gathered around volcanic islands, and the first scientific drilling of large and likely tsunamigenic volcanic island-arc landslide deposits. These cores provide evidence and tests of previous hypotheses for the composition and origin of those deposits. Sites U1394, U1399, and U1400 that penetrated landslide deposits recovered exclusively seafloor sediment, comprising mainly turbidites and hemipelagic deposits, and lacked debris avalanche deposits. This supports the concepts that i/ volcanic debris avalanches tend to stop at the slope break, and ii/ widespread and voluminous failures of preexisting low-gradient seafloor sediment can be triggered by initial emplacement of material from the volcano. Offshore Martinique (U1399 and 1400), the landslide deposits comprised blocks of parallel strata that were tilted or microfaulted, sometimes separated by intervals of homogenized sediment (intense shearing), while Site U1394 offshore Montserrat penetrated a flat-lying block of intact strata. The most likely mechanism for generating these large-scale seafloor sediment failures appears to be propagation of a decollement from proximal areas loaded and incised by a volcanic debris avalanche. These results have implications for the magnitude of tsunami generation. Under some conditions, volcanic island landslide deposits composed of mainly seafloor sediment will tend to form smaller magnitude tsunamis than equivalent volumes of subaerial block-rich mass flows rapidly entering water. Expedition 340 also successfully drilled sites to access the undisturbed record of eruption fallout layers intercalated with marine sediment which provide an outstanding high-resolution data set to analyze eruption and landslides cycles, improve understanding of magmatic evolution as well as offshore sedimentation processes.
机译：IODP Expedition 340从2012年3月至2012年4月在小安的列斯成功地在蒙特塞拉特，马提尼克岛和多米尼加海上钻了一系列钻探场地。这是在火山岛周围聚集的少数钻探场地之一，也是对大型且可能是海啸性火山岛的首次科学钻探。弧形滑坡沉积物。这些核心为这些矿床的组成和成因提供了证据和先前假设的检验。穿透滑坡沉积物的站点U1394，U1399和U1400仅恢复了海底沉积物，其中主要是浊石和半潜质沉积物，而没有碎屑雪崩沉积物。这支持了这样的概念：火山碎屑的崩塌往往会在斜坡折断处停止，并且由于火山岩中物料的初次进入，可能会引发先前已存在的低梯度海底沉积物的广泛而大量的破坏。离岸马提尼克岛（U1399和1400）的滑坡沉积物包括倾斜或微断层的平行地层块，有时被均质沉积物间隔隔开（强烈剪切），而蒙特塞拉特岛U1394站点则穿透了平坦的完整地层块。产生这些大规模海底沉积物破坏的最可能机制似乎是由火山碎屑雪崩加载和切割的近端区域的弯折传播。这些结果对海啸发生的规模具有影响。在某些情况下，与快速进入水中的等体积的航下富含块的质量流相比，主要由海底沉积物组成的火山岛滑坡沉积物往往会形成较小的海啸。远征队340还成功钻探了一些地点，以获取不受干扰的喷发沉积层和海洋沉积物的记录，这些记录提供了出色的高分辨率数据集，用于分析喷发和滑坡周期，增进了对岩浆演化以及海上沉积过程的理解。

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