Sea-level change and storm-surge deposition in a late Holocene Florida salt marsh
Sea-level change and storm-surge deposition in a late Holocene Florida salt marsh
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全新世晚期佛罗里达盐沼的海平面变化和风暴潮沉积
DOI：
10.2110/jsr.68.240
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发表时间：
1998
影响因子：
2
通讯作者：
A. Hine
中科院分区：
文献类型：
--
作者：
S. Goodbred;E. Wright;A. Hine
摘要佛罗里达西部300公里长的海岸线主要是一个开放的海洋沿海沼泽系统。Waccasassa湾位于这一沉积物贫乏地区的中部沿着，目前是一个宽阔的浅海湾，周围环绕着广阔的灯心草盐沼。在这个系统中，沉积物首先沉积在一个森林沼泽约4400至1800卡年BP。同时，大型牡蛎礁生长在海湾附近的古河口。这些沉积物表明，在晚全新世期间，海平面缓慢上升，与其他西佛罗里达海岸系统的建立或回归相关。大约1800 cal yr BP，2-4 km的快速海侵导致了前沼泽的盐沼生长，并在先前未被淹没的高地表面上形成了半咸水沼泽。计算出的海岸线后退速率在此时为10至> 20米/年，而在晚全新世的大部分时间里，后退速率小于3.0米/年。Waccasassa湾事件的发生时间与其他大西洋和墨西哥湾沿岸系统的海侵序列相对应，并支持相对海平面波动约为10000米。1800 cal yr BP.在这次事件之后，海侵过程中被超越的沉积物被改造成低洼的潮汐沼泽。沿海岸边缘的快速沿着加积超过了海平面上升的速度，导致了高潮间带和潮上堤坝的局部发展。有证据表明，风暴潮是这些沉积物输运的主要机制。在Waccasassa湾，风暴潮沉积在沼泽表面增生中发挥了重要作用，将该系统与更典型的潮汐主导的湿地区分开来。在过去的150年里，潮上环境的大部分成为潮汐淹没，有一个广泛的过渡到现代盐沼。这种变化和来自佛罗里达海岸邻近地区的证据暗示了过去几百年海平面的上升。
ABSTRACT A 300-km length of west Florida's coastline is dominated by an open-marine coastal marsh system. Located along the central part of this sediment-poor region, Waccasassa Bay is presently a broad, shallow embayment rimmed by an expansive Juncus roemerianus salt marsh. In this system, sediments were first deposited in a forested swamp from ~ 4400 to 1800 cal yr BP. Contemporaneously, large oyster reefs grew in the embayment near a paleo-river mouth. These deposits indicate a period of slow sea-level rise during the Late Holocene that correlates with the establishment or regression of other west Florida coastal systems. Circa 1800 cal yr BP, a rapid transgression of 2-4 km led to salt marsh growth over the former swamp, and a brackish marsh developed over a previously unflooded upland surface. Calculated rates of shoreline retreat are 10 to > 20 m/yr at this time and compare to < 3.0 m/yr during most of the Late Holocene. Timing of the event in Waccasassa Bay corresponds with transgressive sequences in other Atlantic and Gulf coast systems and supports a relative sea-level fluctuation ca. 1800 cal yr BP. Following this event, sediments overstepped during the transgression were reworked onto the low-lying tidal marsh. Rapid accretion along the shore edge outpaced sea-level rise and led to the local development of high intertidal and supratidal levees. Evidence indicates that storm-driven surge was the principal mechanism of sediment transport for these deposits. In Waccasassa Bay, storm-surge deposition has played a significant role in marsh surface accretion, distinguishing the system from more typically tide-dominated wetlands. Within the past ~ 150 years, most of the supratidal environment became tidally inundated and there was a widespread transition into the modern salt marsh. This change and evidence from adjacent portions of the Florida coast implicate a rise in sea level within the past several hundred years.