New insights into landslide processes around volcanic islands from Remotely Operated Vehicle (ROV) observations offshore Montserrat
New insights into landslide processes around volcanic islands from Remotely Operated Vehicle (ROV) observations offshore Montserrat
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DOI：
10.1002/2015gc005781
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发表时间：
2015-07
期刊：
影响因子：
3.7
通讯作者：
S. Watt;M. Jutzeler;P. Talling;S. Carey;R. Sparks;M. Tucker;A. Stinton;J. K. Fisher;D. Wall-Palmer;S. Moreton
中科院分区：
文献类型：
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作者：
S. Watt;M. Jutzeler;P. Talling;S. Carey;R. Sparks;M. Tucker;A. Stinton;J. K. Fisher;D. Wall-Palmer;S. Moreton
海底滑坡沉积物已被绘制在许多火山岛周围，但其结构，成分和定位的解释受到直接调查沉积物的挑战的阻碍。在这里，我们报告的详细观测蒙特塞拉特周围的四个滑坡沉积物收集的遥控车辆，整合直接成像和采样与沉积物芯和地球物理数据。这些互补的方法使人们能够比以前更全面地了解岛弧火山周围的大规模物质浪费过程。最近的滑坡发生在11.5-14 ka（存款1; 1.7 km 3），并形成了一个径向扩展的丘状存款，在形态上类似于许多陆上碎片雪崩存款。丘状岩由角状熔岩和热液蚀变的碎片组成，这意味着一次深埋的中央陆上塌陷，推测这是从一次喷发时期移走了大部分熔岩，现在在陆上火山记录中几乎没有代表性。一个更大的滑坡（存款2; 10 km 3）发生在距今130 ka，并运送完整的火山建筑物的碎片，高达900米，超过100米高。这些碎片在滑坡中漂流，最好暴露在存款的边缘附近。最大的区块保存了陆上火山角砾岩的原始地层，其下部被从海底侵蚀而来的半远洋泥包裹。蒙特塞拉特南部的滑坡沉积物（沉积物3和5）表明火山岛周围有各种各样的碎片雪崩源岩性。存款5起源于浅淹没陆棚，而不是陆相火山机构，并以碳酸盐碎屑为主。
Submarine landslide deposits have been mapped around many volcanic islands, but interpretations of their structure, composition, and emplacement are hindered by the challenges of investigating deposits directly. Here we report on detailed observations of four landslide deposits around Montserrat collected by Remotely Operated Vehicles, integrating direct imagery and sampling with sediment core and geophysical data. These complementary approaches enable a more comprehensive view of large‐scale mass‐wasting processes around island‐arc volcanoes than has been achievable previously. The most recent landslide occurred at 11.5–14 ka (Deposit 1; 1.7 km3) and formed a radially spreading hummocky deposit that is morphologically similar to many subaerial debris‐avalanche deposits. Hummocks comprise angular lava and hydrothermally altered fragments, implying a deep‐seated, central subaerial collapse, inferred to have removed a major proportion of lavas from an eruptive period that now has little representation in the subaerial volcanic record. A larger landslide (Deposit 2; 10 km3) occurred at ∼130 ka and transported intact fragments of the volcanic edifice, up to 900 m across and over 100 m high. These fragments were rafted within the landslide, and are best exposed near the margins of the deposit. The largest block preserves a primary stratigraphy of subaerial volcanic breccias, of which the lower parts are encased in hemipelagic mud eroded from the seafloor. Landslide deposits south of Montserrat (Deposits 3 and 5) indicate the wide variety of debris‐avalanche source lithologies around volcanic islands. Deposit 5 originated on the shallow submerged shelf, rather than the terrestrial volcanic edifice, and is dominated by carbonate debris.