Atoll lagoons as archives of environmental change: tsunami deposits, reef and island development, and sea level in the Maldives, Indian Ocean

与印度-太平洋地区的许多其他低洼岛国一样，马尔代夫群岛受到海平面上升的威胁，目前海平面上升在很大程度上是全球变暖的结果。除海平面外，珊瑚礁健康状况的恶化和海洋的酸化降低了珊瑚礁和岛屿的增长潜力。其他威胁包括海啸，它暂时淹没了珊瑚礁岛屿。我们的研究旨在探讨这些重要问题。我们计划对马尔代夫进行为期两周的探险，以便使用罗斯菲尔德振动器从两个环礁泻湖收集10-15个沉积物岩芯。这项研究有三个目标，既具有地学意义，也具有社会经济意义。(1)环礁泻湖岩芯可作为近代地质历史中海啸历史的档案。粗粒海啸床将在细粒泻湖泥浆序列中脱颖而出，不能被误认为风暴沉积，因为该群岛由于其赤道位置而没有气旋。这一目标符合德国在印度洋建立海啸预警系统的努力。(2)核心材料将使我们能够调查低洼陆地地区对冰川后海平面上升的反应，冰川后海平面上升将碟形更新世石灰岩岛屿变成沼泽、受限的泻湖，并最终开放环礁泻湖。与现有的边缘礁开发数据一起，这项研究将提供马尔代夫冰后生物礁和岛屿演变的全面图景。(3)作为一个有价值的副产品，我们将能够限制法罗群岛神秘的起源，法罗群岛是马尔代夫几乎独有的较小的圆形珊瑚礁。

Like many other low-lying island nations in the Indo-Pacific region, the Maldives archipelago is threatened by sea-level rise, which at present is largely a consequence of global warming. Apart from sea level, the deteriorating health of coral reefs and the acidification of the ocean reduces the growth potential of coral reefs and islands. Additional threats include tsunamis, which temporarily inundate reef islands. Our study aims at investigating these important issues. We plan a two-week expedition to the Maldives in order to collect 10-15 sediment cores from two atoll lagoons using a Rossfelder vibracorer. The study has three objectives, which have both geoscientific and socio-economic significance. (1) Atoll lagoon cores may serve as archives of the history of tsunamis in the recent geologic past. Coarse-grained tsunami beds will stand out in the successions of fine-grained lagoonal muds, and cannot be mistaken for storm deposits because the archipelago is cyclone-free due to its equatorial location. This objective is in line with the German efforts of establishing a tsunami warning system in the Indian Ocean. (2) The core material will enable us to investigate the response of low-lying land areas to post-glacial sea-level rise, which has turned saucer-shaped Pleistocene limestone islands into swamps, restricted lagoons, and eventually open atoll lagoons. Together with existing data on marginal reef development, this study will provide a comprehensive picture of post-glacial reef and island evolution in the Maldives. (3) As a valuable spin-off, we will be able to constrain the enigmatic origin of faroes, smaller circular reefs that are virtually unique to the Maldives.