Evolution of paraglacial coasts in response to changes in fluvial sediment supply
Evolution of paraglacial coasts in response to changes in fluvial sediment supply
复制标题
DOI：
10.1144/sp388.15
复制
发表时间：
2014-01-01
期刊：
影响因子：
--
通讯作者：
Kelley, J. T.
中科院分区：
文献类型：
--
作者：
Hein, Christopher J.;Fitzgerald, D. M.;Kelley, J. T.
冰缘海岸系统是由直接或间接的冰川作用形成的沉积物在以前被冰覆盖的地形上或附近形成的。本文讨论了构造控制、冰川前进和退缩、海平面变化和海岸过程在缅因州海岸（美国和加拿大）冰缘湾沉积物产生、输送和沿着再分配中的作用。海岸堆积形式在成分上是不均匀的，主要出现在海湾最大的河口的向海边缘;它们的存在直接归因于沿海河流流域内风化岩体侵蚀产生的冰川沉积物的存在。多次冰后期海平面波动推动了这些沉积物在现代低地和内陆架的重新分布。障壁系统形成的核心是冰旁砂最大值，相对海平面下降的时间海侵阶段和增强的河流砂输出。2000-4000年后冰川消退。在随后的海侵过程中，大量的砂和砾石向陆地重新加工，并与额外的河流沉积物结合，形成了现代的屏障系统。今天，河流沉积物负荷减少，人为修改的障碍和河流系统，海平面上升相结合，加剧了长期的海岸侵蚀，并可能最终迫使这些障碍迅速向陆地迁移的状态。
Paraglacial coastal systems are formed on or proximal to formerly ice-covered terrain from sediments with direct or indirect glacial origin. This review addresses the roles of tectonic controls, glacial advances and retreats, sea-level changes, and coastal processes in sediment production, delivery and redistribution along the paraglacial Gulf of Maine coast (USA and Canada). Coastal accumulation forms are compositionally heterogeneous and found primarily at the seaward edge of the Gulf's largest estuaries; their existence is directly attributable to the availability of glacial sediments derived from erosion of weathered plutons within coastal river basins. Multiple post-glacial sea-level fluctuations drove the redistribution of these sediments across the modern lowland and inner shelf. Central to the formation of barrier systems was the paraglacial sand maximum, a time-transgressive phase of relative sea-level fall and enhanced fluvial sand export c. 2000-4000 years following deglaciation. Vast quantities of sand and gravel were reworked landward during the subsequent transgression and combined with additional riverine sediments to form the modern barrier systems. Today, reduced fluvial sediment loads, anthropogenic modifications of barrier and river systems, and sea-level rise have combined to exacerbate long-term coastal erosion and may eventually force these barriers toward a state of rapid landward migration.