Holocene paleostorms identified by particle size signatures in lake sediments from the northeastern United States
Holocene paleostorms identified by particle size signatures in lake sediments from the northeastern United States
复制标题
DOI：
10.1007/s10933-009-9311-1
复制
发表时间：
2010
影响因子：
2.1
通讯作者：
A. Parris;P. Bierman;A. Noren;M. Prins;A. Lini
中科院分区：
文献类型：
--
作者：
A. Parris;P. Bierman;A. Noren;M. Prins;A. Lini
新罕布什尔州和缅因州丘陵地带全新世古洪水的频率和时间是通过对取自六个冰川后湖泊（~0.1–1.4 km2）的沉积物岩心进行 14C 和高分辨率（厘米×厘米）粒度分析来确定的。在河流三角洲前坡底部附近采集了总共九个沉积岩芯（4.5-6 m 长）。每个核心的粒径频率分布的端元建模会产生 3-5 个代表性端元分布，或端元 (EM)。平均和中值颗粒尺寸以及最粗颗粒的相对丰度同时增加，表明暴雨导致流入支流的输送能力增加。在所有 9 个岩心中，粒径数据显示出间歇性高能沉积物迁移事件的明显迹象，而烧失量和磁化率等替代测量则没有，这证明了使用湖泊沉积物岩心进行的古风暴调查中粒径分析的敏感性。该地区风暴引发的洪水在 1.4、2.1、3.0、3.9、6.8、8.2 和 11.5 kcal BP 左右达到峰值，目前频率似乎在增加。新罕布什尔州和缅因州的暴风雨时期与美国东北部全新世期间的其他降水和气候记录密切相关，进一步支持了现代记录，即热带气团是新英格兰极端降水事件的主要驱动力（Ludlum 1996；Konrad 2001；Sisson 和 Gyakum 2004）。
The frequency and timing of Holocene paleofloods in the hilly terrain of New Hampshire and Maine are identified using14C and high-resolution (cm-by-cm) particle size analysis of sediment cores taken from six post-glacial lakes (~0.1–1.4 km2). A total of nine sediment cores (4.5–6 m long) were taken near the base of stream delta foreslopes. End-member modeling of the particle-size frequency distributions from each core produces 3–5 representative end member distributions, or end members (EMs). Concurrent increases in mean and median particle size, and in the relative abundance of the coarsest EM(s), indicate increased transport capacity of inflowing tributaries, resulting from rainstorms. In all 9 cores, particle size data show clear signs of episodic, high-energy sediment transport events where proxy measurements such as loss-on-ignition and magnetic susceptibility do not, demonstrating the sensitivity of particle size analysis in paleostorm investigations made using lake sediment cores. Floods caused by storms in this region peaked around 1.4, 2.1, 3.0, 3.9, 6.8, 8.2, and 11.5 ka cal BP, and presently appear to be increasing in frequency. Periods of storminess in New Hampshire and Maine correlate well with other records of precipitation and climate in the northeastern United States during the Holocene, further supporting modern records which show tropical air masses as a primary driver of extreme precipitation events in New England (Ludlum 1996; Konrad 2001; Sisson and Gyakum 2004).