| 海南岛洋浦港现代沉积速率 |
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| 引用本文： | 潘少明 Smith,JN.海南岛洋浦港现代沉积速率[J].沉积学报,1994,12(2):86-93. |
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| 作者姓名： | 潘少明 Smith JN |
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| 作者单位： | 南京大学海岸与海岛开发国家试点实验室 |
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| 摘 要： | 通过对海南岛洋浦港4个沉积柱样沉积结构?Pb-210?Cs-137放射性强度的分析,研究该区的现代沉积速率?洋浦港海域为一潮汐叉道,沉积物的分布主要受潮流分布的影响,近代沉积过程具有阶段性的特点,在港口的许多地方正持续着侵蚀与堆积的循环?洋浦深槽的沉积物主要为粉砂?粘土,砂质物主要由河流?落潮流带入,而大部分的粘土颗粒物质由涨潮流带入深槽,在高平潮水动力能量减小的条件下沉降下来,由于这种沉积物传输的双向性导致了极易变化的沉积结构?粗砂粉砂的交替沉积反映了风暴潮事件对该区域的影响?根据Pb-210?Cs-137测年法,洋浦港深槽的现代沉积速率为0.5~2cm/a,本世纪初以来,拦门沙处于稳定增长的状态,其平均增长率为1~2cm/a?该方法应用于地质年代学具有实际的意义?
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| 关 键 词： | 海南岛洋浦港 沉积速率 Pb－210 Cs－137 |
Recent Sedimentation Rates in Yangpu Harbour on Hainan Island |
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| Institution: | 1 State Pilot Laboratory of Cost & Island Exploitation. Nanjing University; |
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| Abstract: | Four sediment cores, collected in Yangpu Harbour on Hainan Island,were analyzed for textural parameters and Pb- 210, Cs-137 activities,Yangpu Harbour is tidally flushed and has sediment distribution pattern which is related primarily to the tidal current pattern. Sandy(fine and coarse sllty sand ) material is distributed along the tracts of relatively high speed tidal currents underlying the shallower regions of the harbour while finer-grained,silty muds tend to accumulate in the deeper parts of the tidal channel itself. Measurements of textural paramenters have indicated that sedimentation is episodic in many sections of the harbour with successive cycles of particle erosion and deposition leading to the variable accumulation of material,particularly in the tidal channel. Because of complex stratigraphy of interbedded layers of sand and mud,Pb-210 profiles in Yangpu Harbour reveal abnormal distributions. Since the Pb-210 activity was almost exclusively associated with the finegrained,clay,component of the sediment load,the nomalization of these data to the%clay content of the sediment permitted the determination of depositional rates,despite instances of variability in the Pb- 210 activities. The distributions of Cs- 137 in two cores were measured,both the position of the horizon (corresponding to the first appearance of Cs-137 in the environment )and the peak (corresponding to the period of maximum deposition ) have been used to determine sedimentation rates. Rates based on the position of peak of Cs- 137 profile are in good agreement with that based on Pb-210 dating,and rates based on the occurrence of the horizon are slightly larger than that based on Pb-210 dating. Sedimentation rates,determined using P1i-210 and Cs-137 dating methods,were 0. 5-2cm/y in the sediments underlying the tidal channel,and were 1~2cm/y in the sediments on the swash platform area("block gate shoal") during past 100 years. |
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