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

与印度洋-太平洋地区的许多其他低地岛国一样，马尔代夫群岛受到海平面上升的威胁，目前海平面上升主要是全球变暖的后果。除海平面外，珊瑚礁健康状况恶化和海洋酸化也降低了珊瑚礁和岛屿的生长潜力。其他威胁包括海啸，海啸会暂时淹没珊瑚礁岛屿。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考察，以便使用Rossfelder振动仪从两个环礁泻湖收集10-15个沉积物岩心。该研究有三个目标，具有地球科学和社会经济意义。(1)环礁泻湖的岩芯可以作为近期地质历史中海啸历史的档案。粗粒度的海啸床将在细粒泻湖泥的继承中脱颖而出，并且不能被误认为是风暴沉积物，因为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后期海平面上升的反应，这使得碟形更新世石灰岩岛屿变成沼泽，限制泻湖，并最终开放环礁泻湖。这项研究将结合关于边缘珊瑚礁发展的现有数据，全面介绍马尔代夫冰后期珊瑚礁和岛屿的演变情况。(3)作为一个有价值的副产品，我们将能够限制法罗群岛的神秘起源，较小的圆形珊瑚礁实际上是马尔代夫独有的。

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.