Sedimentary records of intense storms in Holocene barrier sequences, Maine, USA
Sedimentary records of intense storms in Holocene barrier sequences, Maine, USA
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DOI：
10.1016/j.margeo.2004.05.007
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发表时间：
2004-09-15
期刊：
影响因子：
2.9
通讯作者：
van Heteren, S
中科院分区：
文献类型：
--
作者：
Buynevich, IV;FitzGerald, DM;van Heteren, S
海岸形态学、地球物理学（探地雷达[GPR]）和沉积学数据记录了缅因州中南部（Hunnewell和Flat Point屏障）和西南部（Saco Bay屏障）沿海分区的沿着桑迪屏障的极端风暴事件。Hunnewell屏障在1978年暴风雪的暴露悬崖后面包含四个等距的掩埋风暴悬崖，这场百年一遇的风暴侵蚀了100多英寸的海岸线，造成了广泛的财产损失。这些陡崖比正常的海滩斜坡陡3 - 5度，由含有50%以上重矿物的沙子组成。重矿物产生明显的地下反射，有利于风暴崖的埋藏潮上部分的位置和古代风暴后海岸线位置的映射。图像中的陡坎可能形成于1.5-2.0 ka BP。平点障壁由一个覆盖着横向延伸的、向海变薄的淡水泥炭层和被风成沙覆盖的沉积层序组成。这种地层学表明，沼泽的大小随时间而变化，在过冲事件和风成沉积和扩大整个冲覆片在延长期的障碍稳定性收缩。主要的过冲事件伴随着障碍夷平面化和湿地扩张，可能与新英格兰历史上的第一次风暴有关，即1635年的“大殖民飓风”。沿着萨科湾的近现代和中全新世风暴事件的证据包括冲刷单元和沼泽脊。从4.5 ka BP到现代，冲刷物与盐沼泥炭交错。在现有的和以前的潮汐入口后面存在孤立的桑迪脊，反映了大风暴期间沼泽和高潮间带泥滩的漫顶。放射性碳年龄表明，这一过程发生在不同的位置沿着萨科湾屏障复杂的3至1 ka BP。(C)2004 Elsevier B. V.保留所有权利。
Coastal-morphological, geophysical (ground-penetrating radar [GPR]), and sedimentological data document extreme storm events along the sandy barriers of Maine's south-central (Hunnewell and Flat Point barriers) and southwestern (Saco Bay barriers) coastal compartments. The Hunnewell barrier contains four equally spaced buried storm scarps behind the exposed scarp of the Blizzard of 1978, a 100-year storm that eroded more than 100 in of shoreline, causing extensive property loss. These scarps dip 3 - 5 degrees steeper than the normal beachface slope and consist of sands with more than 50% heavy minerals. The heavy minerals produce distinct subsurface reflections that facilitate the location of buried supratidal parts of storm scarps and the mapping of ancient poststorm shoreline positions. The imaged scarps likely formed within the past 1.5-2.0 ka BP. The Flat Point barrier consists of a prograded sequence overlain by a laterally extensive, seaward-thinning layer of freshwater peat and capped by aeolian sands. This stratigraphy suggests that the bog varied in size through time, contracting during overwash events and aeolian deposition and expanding across washover sheets during extended periods of barrier stability. The main overwash event accompanied by barrier planation and wetland expansion may be linked to the first historical storm in New England, the "Great Colonial Hurricane" of 1635.Evidence of near-modem and mid-Holocene storm events along Saco Bay includes washover units and marsh ridges. Washovers interfinger with saltmarsh peat that ranges in age from 4.5 ka BP to modem. The presence of isolated sandy ridges behind existing and former tidal inlets reflects overtopping of marshes and high intertidal mudflats during major storms. Radiocarbon ages indicate that this process took place at different locations along the Saco Bay barrier complex from 3 to 1 ka BP. (C) 2004 Elsevier B.V. All rights reserved.