Evaluation of Coastal Response to Sea-Level Rise from Holocene Stratigraphic Records: A Step Towards Coastal Forecasting

根据全新世地层记录评估沿海对海平面上升的响应：向海岸预测迈进了一步安东尼奥·罗德里格斯和约翰·b·安德森政府间气候变化专门委员会的共识是，由于全球变暖，未来海平面上升的速度将会加快。海平面上升速度加快将对世界海岸产生一系列不利影响，例如湿地丧失和海岸侵蚀加速，但这些变化的幅度仍不可预测。应该通过检查全新世期间海岸变化的地质记录来改进对未来海平面上升速度的预测，当时海平面的上升速度与未来的预测相似。海岸对海平面上升的反应最好的记录是在切割的河流山谷中发现的。从三个墨西哥湾海湾，特别是莫比尔湾，加尔维斯顿湾和科珀斯克里斯蒂湾切割的山谷填充物将被检查和比较。这些海湾位于不同的气候带内，由不同形态的河流系统滋养。来自三个海湾的初步数据已经确定了在全新世期间发生的一段海岸线快速退缩。在加尔维斯顿湾，这一事件导致河口环境向陆地移动了数十公里，屏障海岸线被淹没并搁浅在大陆架上作为一个银行（希尔德银行）。假设沿海沉降速率和河流流量的变化不是观测到的沿海后退事件的原因。该假设将通过收集高分辨率地震、沉积物岩心（长达30米的岩心）和来自每个海湾的古生物学数据来验证，以确定洪水表面。从植物碎片和关节软体动物样本中获得的放射性碳年代，在每个海湾内的整个洪水表面倾斜轴上下的许多地点取样，将限制事件的时间和海岸变化的速度。海湾之间的洪水表面的相互关系，连同沉积和压实率的计算以及从基底泥炭沉积物中生成的海平面曲线，将有助于区分气候变化和海平面事件引起的下沉。这项工作将有助于量化沿海对强迫机制的反应，并将创建适合于通过后播测试沿海预报模型的数据集。

AbstractEvaluation of Coastal Response to Sea-Level Rise from Holocene Stratigraphic Records: A Step Towards Coastal ForecastingAntonio Rodriguez and John B. Anderson The consensus of the Intergovernmental Panel on Climate Change was that the rate of sea-level rise will increase in the future as a result of global warming. An increased rate of sea-level rise will have a number of adverse impacts on world coasts, such as wetlands loss and accelerated coastal erosion, but the magnitude of these changes remains unpredictable. Predictions of coastal response to future sea-level rise rates should be improved by examining the geological record of coastal change during the Holocene, when sea level was rising at rates similar to future predictions. The best records of coastal response to rising sea level are found in incised fluvial valleys. Incised valley fill from three Gulf of Mexico bays, specifically Mobile Bay, Galveston Bay, and Corpus Christi Bay will be examined and compared. These bays are located within differing climatic belts, and are fed by morphologically distinct fluvial systems. Preliminary data from all three bays has identified an episode of rapid shoreline retreat that occurred during the Holocene. In Galveston Bay, this event resulted in the estuarine environment being shifted tens of kilometers landward and the barrier shoreline being submerged and stranded on the continental shelf as a bank (Heald Bank). The hypothesis is that variations in the rate of coastal subsidence and river discharge were not the cause of the observed coastal backstepping events. The hypothesis will by tested by collecting high-resolution seismic, sediment core (up to 30 m-long cores), and paleontologic data from each bay to identify flooding surfaces. Radiocarbon age dates obtained from plant fragments and articulated mollusks sampled at numerous locations above and below the entire dip axis of flooding surfaces within each bay will constrain the timing of the events and the rates of coastal change. Correlation of flooding surfaces between the bays, together with calculations of sedimentation and compaction rates and the generation of sea-level curves from basal peat deposits, will aid in distinguishing variations in climate and subsidence from sea-level events. This work will help quantify coastal response to forcing mechanisms, and will create data sets appropriate for testing coastal forecasting models by hindcasting.