Mississippi Delta subsidence primarily caused by compaction of Holocene strata
Mississippi Delta subsidence primarily caused by compaction of Holocene strata
复制标题
DOI：
10.1038/ngeo129
复制
发表时间：
2008-03
期刊：
影响因子：
--
通讯作者：
T. Törnqvist;D. Wallace;J. Storms;J. Wallinga;R. V. Dam;M. Blaauw;Mayke S. Derksen;C. Klerks
中科院分区：
文献类型：
--
作者：
T. Törnqvist;D. Wallace;J. Storms;J. Wallinga;R. V. Dam;M. Blaauw;Mayke S. Derksen;C. Klerks
海岸下沉造成海平面上升、海岸线侵蚀和湿地丧失，对沿海人口构成威胁。这一点在2005年遭受卡特里娜飓风破坏的美国南部密西西比三角洲尤为明显。保护性湿地的丧失被认为是造成大规模洪水破坏的一个关键因素。路易斯安那州沿海地区沉降的原因，归因于各种因素，如浅层压实和深层地壳过程，仍然存在争议，，。目前对沉降速率的估计相差几个数量级。在这里，我们使用了一系列放射性碳定年沉积物芯从密西西比三角洲分析晚全新世沉积物和评估压实率。我们发现，千年尺度的压实率主要与泥炭可以达到每年5毫米，超过最近的模型预测值，。在当地和几十年到几个世纪的时间尺度上，速率可能是每年10毫米或更多。我们的结论是，压实的全新世地层有助于显着异常高的相对海平面上升率和沿海湿地的损失在密西西比三角洲，并可能导致其他有机丰富，往往人口稠密的沿海平原沉降。
Coastal subsidence causes sea-level rise, shoreline erosion and wetland loss, which poses a threat to coastal populations. This is especially evident in the Mississippi Delta in the southern United States, which was devastated by Hurricane Katrina in 2005. The loss of protective wetlands is considered a critical factor in the extensive flood damage. The causes of subsidence in coastal Louisiana, attributed to factors as diverse as shallow compaction and deep crustal processes, remain controversial,,,,,,,,,. Current estimates of subsidence rates vary by several orders of magnitude,. Here, we use a series of radiocarbon-dated sediment cores from the Mississippi Delta to analyse late Holocene deposits and assess compaction rates. We find that millennial-scale compaction rates primarily associated with peat can reach 5 mm per year, values that exceed recent model predictions,. Locally and on timescales of decades to centuries, rates are likely to be 10 mm or more per year. We conclude that compaction of Holocene strata contributes significantly to the exceptionally high rates of relative sea-level rise and coastal wetland loss in the Mississippi Delta, and is likely to cause subsidence in other organic-rich and often densely populated coastal plains.