A multiproxy analysis of extreme wave deposits in a tropical coastal lagoon in Jamaica, West Indies
A multiproxy analysis of extreme wave deposits in a tropical coastal lagoon in Jamaica, West Indies
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DOI：
10.1007/s11069-020-04284-2
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发表时间：
2020-09
期刊：
影响因子：
3.7
通讯作者：
S. Palmer;Michael J. Burn;J. Holmes
中科院分区：
文献类型：
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作者：
S. Palmer;Michael J. Burn;J. Holmes
加勒比区域的小岛屿发展中国家容易受到自然灾害的影响，包括地震、海啸和热带气旋，这些灾害可能造成广泛的破坏。这些灾害的沉积档案通常在沿海泻湖中保存得很好；然而，加勒比地区的研究很少采用多代理方法进行重建。在这里，我们提供了一个1200年的多代理记录，记录了牙买加南海岸红树林泻湖内沉积的极端冲刷事件。海牛湾泻湖是一个永久的淡淡水红树林泻湖，由低海拔的碳酸盐海滩与加勒比海分开。沿5条滨向样带恢复的15个沉积物岩心含有富含介形虫的自生碳酸盐湖泥，其间穿插着有机湖泥和红树林泥炭床。岩心中含有多个古冲蚀沉积的证据，这些沉积物很容易通过沉积学、地球化学和微化石组合来区分。高盐条件在记录的早期（约800至900年）占主导地位，我们推断，在约1290至1400年之前发生的一次极端海浪事件之后，泻湖水域变新鲜，随后红树林群落扩大。我们将主要的历史冲积沉积限制在1810-1924 CE （2σ； 71%概率），这是一个以极端构造和气象事件为特征的时期，其中包括1907年金斯顿大地震和当地飓风活动增强的一段。虽然间接证据的平衡表明，该沉积物可能是在1907年地震引起的海啸期间安置的，但我们目前无法根据其沉积学特征区分构造和气象驱动的冲刷事件。
The Small Island Developing States (SIDS) of the Caribbean Region are vulnerable to natural hazards including earthquakes, tsunamis and tropical cyclones that can cause widespread devastation. Sedimentary archives of these hazards are often well-preserved in coastal lagoons; however, few studies in the Caribbean have adopted a multiproxy approach to their reconstruction. Here, we present a 1200-year multiproxy record of extreme washover events deposited within a coastal mangrove lagoon on the south coast of Jamaica. Manatee Bay lagoon is a permanent fresh-brackish-water mangrove lagoon separated from the Caribbean Sea by a low-elevation carbonate beach. Fifteen sediment cores recovered along five shore-normal transects contain ostracod-rich authigenic carbonate lake muds interspersed with beds of organic lake mud and mangrove peat. The cores contain evidence of multiple palaeo-washover deposits that are readily distinguished by their sedimentology, geochemistry and microfossil assemblages. Hypersaline conditions dominated the early part of the record (~ 800 to 900 CE), and we infer a freshening of lagoonal waters and the subsequent expansion of the mangrove community following an extreme wave event that occurred some time before ~ 1290 to 1400 CE. We constrain the primary historical-washover deposit to 1810–1924 CE (2σ; 71% probability), a period characterised by extreme tectonic and meteorological events, which include the Great Kingston Earthquake of 1907 and a local episode of enhanced hurricane activity. Whilst the balance of circumstantial evidence indicates that the deposit was probably emplaced during the tsunami generated by the 1907 earthquake, we are currently unable to differentiate between tectonically and meteorologically driven washover events based on their sedimentological characteristics.