摘要
1998年 11～ 12月和 1999年 8～ 9月各一个月对月湖进行的野外工作 ,共取得表层沉积物样品 131个 ,应用激光粒度仪并结合传统的筛分法对这些样品进行粒度分析 ,进行矩法计算获得粒度参数。采用Gao命名方法 ,将沉积物划分出 5种主要类型。利用Gao -Collins粒径趋势分析模型 ,计算该区沉积物粒径趋势所显示的沉积物净搬运方向 ,结果表明 ,沉积物从四周向湖中心搬运 ,同时显示湾顶的西部和北部、涨潮三角洲以及湖心等地貌单元是沉积的优势区域。
surface sediment samples were collected from Yuehu during November- December 1998 and August-September 1999, respectively.These samples were analyzed using a Cilas940 L Laser Analyzer and by sieving (for particles with a diameter of <2 mm and >2 mm, respectively) to obtain grain size parameters. Three grain size parameters, i. e., mean grain size(μ), sorting coefficient(δ) and skewness(sk) are then calculated by a moment method.Five main sediment types are present in Yuehu according to the sediment classification scheme proposed by Shu Gao(1993, slight modification based on Folk(1980) classification scheme). The result shows the sediment appears annular distribution and is mainly composed of fine materials: From bank to center the sediment becomes finer gradually, i.e., from gravel sand, muddy sand, sandy mud to mud in turn. Sand is only distributed on ebb delta and north-east corner of the lake. There is a close relationship between mean grain size for sediment and sediment types in Yuehu where the mud area is mostly enclosed by 6 contour. The mean grain size for sandy mud is between 6 and 4 and muddy sand is between 4 and 2. In the sand and gravel sand distributed area the mean grain size is less than 2. Sorting coefficient and skewness value for sediment in Yuehu is 2.0～2.5 and 1～2 respectively. But the sediment located over flood delta is not well sorted with the sorting coefficient value between 3.0 and 3.5. At the same time the sediment near the mouth is negatively skewed with a value of 0.5 and the skewness is near 0 in a small area to the east of the center. The two dimensional model for grain size trend analysis proposed by Gao and Collins(1992 ) is adopted to identify sediment transport pathways in the study area. The net sediment transport pathways derived by using this model show that sediment is transported from bank towards the center, except the net sediment transport pathways are not obvious over ebb delta and main channel.At the same time the result shows that the north and west part of the top of the lake, flood delta and center are deposition centers. Such patterns are highly consistent with the sediment distribution pattern. Therefore this model is applicable for such a small area as Yuehu.
出处
《地理研究》
CSCD
北大核心
2002年第6期707-714,共8页
Geographical Research
基金
国家 8 6 3项目 (2 0 0AA6 330 10 )
