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首页> 外文期刊>Geochemistry, geophysics, geosystems >New insights into landslide processes around volcanic islands from Remotely Operated Vehicle (ROV) observations offshore Montserrat
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New insights into landslide processes around volcanic islands from Remotely Operated Vehicle (ROV) observations offshore Montserrat

机译：蒙特塞拉特近海的遥控车（ROV）观测对火山岛周围的滑坡过程有新见解

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摘要

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 km(3)) 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 km(3)) occurred at approximate to 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.
机译：海底滑坡沉积物已经绘制在许多火山岛周围，但是直接研究沉积物的挑战阻碍了对它们的结构，组成和位置的解释。在这里，我们报告了通过遥控车辆收集的蒙特塞拉特周围四处滑坡沉积物的详细观测结果，并将直接图像和采样与沉积物核心和地球物理数据相结合。这些补充方法使岛弧火山周围大规模的大规模消融过程比以前可获得的更全面。最近一次滑坡发生在11.5-14 ka（沉积1; 1.7 km（3）），形成了一个放射状扩展的山形沉积物，其形态与许多地下碎屑雪崩沉积物相似。吊床包含有角的熔岩和热液蚀变的碎片，这意味着深层的中央大气层塌陷，据推断已从火山喷发时期清除了大部分熔岩，而现在火山喷发在火山喷发记录中所占的比例很小。较大的滑坡（沉积2; 10 km（3））发生在大约130 ka处，并运输了完整的火山大厦碎片，横跨900 m的高度超过100 m高。这些碎片被漂流到滑坡中，最好暴露在矿床边缘附近。最大的地块保留了地下火山角角砾岩的主要地层，其下部被包裹在从海底侵蚀的中海泥中。蒙特塞拉特以南的滑坡沉积物（沉积物3和5）表明火山岛周围的泥石雪崩源岩性多种多样。沉积物5起源于浅埋的架子，而不是地面火山的建筑物，并且以碳酸盐碎片为主。

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