Coastal dynamics under conditions of rapid sea-level rise: Late Pleistocene to Early Holocene evolution of barrier–lagoon systems on the northern Adriatic shelf (Italy)
Coastal dynamics under conditions of rapid sea-level rise: Late Pleistocene to Early Holocene evolution of barrier–lagoon systems on the northern Adriatic shelf (Italy)
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DOI：
10.1016/j.quascirev.2008.02.009
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发表时间：
2008-06
影响因子：
4
通讯作者：
J. Storms;G. Weltje;G.J.S. Terra;A. Cattaneo;F. Trincardi
中科院分区：
文献类型：
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作者：
J. Storms;G. Weltje;G.J.S. Terra;A. Cattaneo;F. Trincardi
这项对两个保存完好的屏障系统的多学科案例研究将放射性碳测年、粒度分布、高分辨率地震和陆架测深分析与古环境条件（潮汐、波浪、海平面变化）重建和屏障泻湖系统正演模型结合起来，提供了15至8kaBP期间亚得里亚海北部陆架大片区域海岸海侵演化的综合视图。古环境重建表明，在最古老的保存完好的屏障系统（∼90m水深；14.3calkaBP）的形成过程中，潮汐幅度增大、低能波浪气候和海平面上升速度较高（高达60mm/a）。较年轻的屏障系统（水深42m；10.5calkaBP）是在潮汐幅度较低、波浪能量较高和海平面上升速率较低（10mm/a）的条件下形成的。正演模型表明，如果假设所有其他因素相同，海侵期间越过障壁岛的概率与潮汐幅度成反比。最古老的堰塞湖系统是在潮汐幅度较大的条件下发展起来的，这使得海侵速度很快。然而，该系统显然无法跟上融水脉冲 1A 导致的海平面异常高的上升速度。由于先前的地形，最年轻的屏障系统似乎已经被淹没在原地。当屏障系统越过古老的更新世冲积平原时，后屏障容纳量的迅速增加导致岸面和后屏障沉积之间突然不平衡，从而导致屏障超越。尽管 BarSim 模型表明潮汐沉积可以降低跨越屏障的可能性，但还有其他驱动机制（在我们的例子中是极快的海平面上升和先前的地形），这些机制在解释亚得里亚海北部屏障泻湖系统的海侵海岸演化方面更具决定性。对亚得里亚海北部陆架海侵沟壑表面上方采集的岸面沉积物进行的粒度分析表明，沉积物粒度与沉积期间海平面上升速率之间存在明显的关系，这意味着渐进式分选一定是非常有效的。
This multidisciplinary case study of two preserved barrier systems combined the analysis of radiocarbon datings, grain-size distributions, high-resolution seismics, and shelf bathymetry with reconstructions of palaeo-environmental conditions (tides, waves, sea-level change) and forward modelling of barrier–lagoon systems, to provide an integrated view of the coastal transgressive evolution of a large sector of the northern Adriatic shelf between 15 and 8kaBP. Palaeo-environmental reconstructions point to increased tidal amplitude, low-energy wave climate and high rates of sea-level rise (up to 60mm/a) during the formation of the oldest preserved barrier system (∼90m water depth; 14.3calkaBP). A younger barrier system (42m water depth; 10.5calkaBP) formed under conditions of lower tidal amplitude, higher wave energy and a lower rate of sea-level rise (10mm/a). Forward modelling suggests that the probability of barrier-island overstepping during transgression is inversely proportional to tidal amplitude, if all other factors are assumed equal. The oldest barrier–lagoon system developed under conditions of large tidal amplitude, which permitted rapid transgression. However, this system apparently failed to keep up with the anomalously high rate of sea-level rise resulting from melt-water pulse 1A. The youngest barrier system appears to have drowned in place due to antecedent topography. As the barrier system transgressed over an ancient Pleistocene alluvial plain, the rapid increase in backbarrier accommodation caused an abrupt disequilibrium between shoreface and backbarrier sedimentation, which led to barrier overstepping. Although BarSim modelling indicates that tidal deposition can reduce the probability of barrier overstepping, there are other driving mechanisms (in our case extremely rapid sea-level rise and antecedent topography), which are more determinative in explaining the transgressive coastal evolution of barrier–lagoon systems in the northern Adriatic Sea. Grain-size analysis of shoreface deposits sampled above the transgressive ravinement surface across the northern Adriatic shelf indicate a distinct relation between the sediment grain size and the rate of sea-level rise during deposition, which implies that progressive sorting must have been highly effective.