| 基于大样本14 C测年资料的 华北平原沉积速率研究* |
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| 引用本文： | 许炯心.基于大样本14 C测年资料的 华北平原沉积速率研究*[J].第四纪研究,2007,27(3):437-443. |
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| 作者姓名： | 许炯心 |
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| 作者单位： | 中国科学院地理科学与资源研究所陆地水循环与地表过程重点实验室,北京,100101 |
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| 摘 要： | 华北平原是我国研究程度较高的地区,历年来积累了大量的14 C测年资料。从这些资料中尽可能地提取沉积速率的信息,并进而研究华北平原沉积速率的变化及其与流域自然和人文环境变化之间的关系,是一个有重要意义的问题。利用华北平原456个地点的14 C年龄与样品埋深资料,计算出了各个样品所在层位沉积以来的平均沉积速率(RT),以此来近似反映各地点的平原沉积速率,并据此建立了RT随时间的变化关系。从古至今, RT有明显的增大趋势。以点群的上包线反映各时代的平原最大沉积速率,该指标可以反映华北平原的主体即黄河下游冲积平原的沉积速率。发现了最大平均沉积速率随时间变化过程中的4个突变点,分别为10000aB.P. , 5000aB.P. , 3000aB.P. 和1400aB.P. 。4个突变点将上包线分成5条折线,由此可以将近4万年以来的变化分成5个阶段。从古至今,5条折线的斜率增大,反映了平原沉积的加速过程; 并对4个突变点的成因进行了解释。阶段1,阶段2和阶段3沉积速率的加速是由自然原因造成的; 阶段4和阶段5沉积速率的加速则是由自然和人为原因共同造成的。从456个地点的14 C年龄与样品埋深资料中提取了距今4万年以来华北平原的平均沉积速率的信息,计算出平均沉积速率为0.9mm/a。按此求出,近4万年以来华北平原的沉积总厚度为36m。
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| 关 键 词： | 沉积速率 14 C测年 气候变化 人类活动 华北平原 |
| 文章编号： | 1001-7410（2007）03-437-07 |
| 收稿时间： | 2006-08-20 |
| 修稿时间： | 2006-11-25 |
A STUDY OF DEPOSITIONAL RATE IN THE NORTH CHINA PLAIN DURING THE PAST 40000 YEARS, BASED ON 14 C DATING DATA FROM A LARGE WEALTH OF SAMPLES |
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| Xu Jiongxin.A STUDY OF DEPOSITIONAL RATE IN THE NORTH CHINA PLAIN DURING THE PAST 40000 YEARS, BASED ON 14 C DATING DATA FROM A LARGE WEALTH OF SAMPLES[J].Quaternary Sciences,2007,27(3):437-443. |
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| Authors: | Xu Jiongxin |
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| Institution: | Institute of Geographical Sciences and Natural Resources Research, Key Laboratory for Water Cycle and Related land Surface Processes, Chinese Academy of Sciences, Beijing 100101 |
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| Abstract: | The North China Plain is an area where much research in Quaternary geology has been done and a large number of 14C dating data is available from published materials. Extracting information of plain sediment depositional rate from these data and then studying the temporal variation of depositional rate in relation with varying natural conditions and human activities is an issue of great importance. Using 14C dating data from 456 locations in the North China Plain, average depositional rate (RT) for the period from the year when the sample was deposited to present has been calculated, and the temporal variation in RT are plotted. The resulting curve shows an increasing trend in the past 40000 years. The upper envelop line of the scattering points is used to reflect the maximum values of RT, which is referred to as RT,max. This index reflects the deposition of the lower Yellow River Plain, the main body of the North China Plain. The fitted upper envelop line indicates 4 breaks, occurring in the time of 10000aB.P., 5000aB.P., 3000aB.P., and 1400aB.P., respectively. The 4 breaks divide the fitted line into 5 straight-line segments, representing 5 stages of plain sediment accumulation in the past 40000 years. The slope of the 4 segments increases, reflecting the accelerating process in the plain deposition. An explanation has been given to the formative cause of the 4 breaks. Stages 1, 2, and 3 occurred due to natural environmental changes, and stages 4 and 5 was due to the joint influence of both natural and human factors. Information has been extracted from 456 samples for estimating the average depositional rate of the whole North China Plain during a period of 40000 years, which has been calculated as 0.9mm/a, and thus, the total sediment thickness in the past 40000 years has been estimated as 36m in the plain. |
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| Keywords: | sedimentation rate ^14C dating climate change human activity North China Plain |
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