Taihu Lake, lower Yangtze drainage basin: evolution, sedimentation rate and the sea level
Taihu Lake, lower Yangtze drainage basin: evolution, sedimentation rate and the sea level
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DOI：
10.1016/s0169-555x(01)00115-5
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发表时间：
2001-11
期刊：
影响因子：
3.9
通讯作者：
Jian Wang;Xia Chen;Xiao-hua Zhu;Jinliang Liu;William Y. B. Chang
中科院分区：
文献类型：
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作者：
Jian Wang;Xia Chen;Xiao-hua Zhu;Jinliang Liu;William Y. B. Chang
通过对太湖两个全新世沉积物钻孔的研究，对太湖沉积物进行了结构构造、微体化石、磁化率和全新世地层学等方面的分析。结果表明，早期太湖地区主要由西太湖洼地和东太湖低漫滩组成。全新世早期，海平面处于较低水平，这两个地区之间不存在水力联系。岩心沉积物、微体化石和磁性证据表明，西太湖早在6000年前就开始被咸水淹没，而东太湖仍为淡水环境。在6000 B. P.之后，4600-3500 B. P.后，随着海平面的上升，淡水水位进一步上升，湖水逐渐淹没整个湖泊，两湖合并。形成于东太湖。高沉降率西太湖湖相沉积物中的沉积速率（0.42-0.35 mm/a）发生在~11,000 - 5000 B. P.（1.54 mm/年）仅发生在6500 ~ 5500 B. P.这一很短的时期内，西太湖和东太湖的沉积速率已降至非常低的值（<0.10 mm/年）。全新世中晚期西太湖和东太湖的低沉积速率解释了5500 B. P.以后海平面上升的减速和海岸向海的快速扩张。
The present study focuses on two Holocene sediment boreholes in Taihu Lake, sunk to examine the lake sediment including sedimentary texture and structure, microfossils, magnetic susceptibility and radiocarbon-dated Holocene stratigraphy. Results demonstrate that the early Taihu Lake area consisted primarily of West Taihu Lake depression and a low floodplain in the East Taihu Lake area. No hydraulic connection existed between the two sectors during the early Holocene when sea level stood at lower level. Core sediments, microfossil and magnetic evidence records that West Taihu Lake began to be inundated by brackish water prior to 6000 years ago, while East Taihu Lake still remained a freshwater setting. After 6000 B.P., a further rise in freshwater table in response to sea-level fluctuation progressively drowned the entire lake, coalescing the two parts after 4600–3500 B.P. Our coring revealed that the lacustrine sediment began to form in West Taihu Lake as early as 11,000 years ago, while it happened much later (only after 5700 B.P.) to form in East Taihu Lake. High sedimentation rates (0.42–0.35 mm/year) in lacustrine deposits of West Taihu Lake occurred between ~11,000 and 5000 B.P. In contrast, the high sedimentation rates (1.54 mm/year) in East Taihu Lake occurred only within a very short time period, from ~6500 to 5500 B.P. Since then, sedimentation rates have decelerated to a very low value (<0.10 mm/year) in both West and East Taihu Lakes. The low sedimentation rate of West and East Taihu Lake of the middle and late Holocene explains the deceleration of the sea-level rising after 5500 B.P. and the rapid coastal progradation seaward.