海南岛周边海域表层沉积物粒度分布特征

Characteristics of Grain Size Distributions of Surface Sediments in the Hainan Island Offshore Area

对采自海南岛周边海域的533个表层沉积物样品(站位水深为0～174m,平均水深为49m)作了粒度分析、粒度参数计算和多元统计分析,并进行了沉积物分类和分布特征的研究。结果表明:(1)表层沉积物的粒级组成为-1φ～>11φ,主要粒级是6～9φ,占55.62%;沉积物类型主要为砾石、砂砾石、砾石质砂、砂、粉砂、粉砂质砂、砂质粉砂、粘土质粉砂和砂-粉砂-粘土9种,其中,砾石、砂、粉砂和粘土百分含量分别为1.14%,22.66%,52.50%和23.70%。(2)沉积物的平均粒径范围为-1.56～7.57φ,平均值为5.87φ;偏态的范围为-0.35～0.77,平均值为0.00;峰态的范围为0.58～3.05,平均值为1.01;分选系数为0.60～3.72φ,平均值为2.24φ。(3)R型聚类分析结果表明表层沉积物基本上分为粗、细两大类:粗颗粒沉积物由-1φ～3φ粒级组成,细颗粒沉积物由4φ～>11φ组成,各粒级归类良好,图形清晰。R型因子分析结果表明前四种因子累计特征值比例达到92.80%,因子1主要由7φ～>11φ的正载荷和0φ～2φ的负载荷组成,因子2主要由5φ～6φ的正载荷组成,因子3则由3φ～4φ的负载荷组成,因子4主要由-1φ负载荷组成。(4)研究区粗粒沉积物主要位于水动力较强、物质来源多种的沉积环境,并多经历了后期的现代细粒沉积作用的改造,细粒沉积物主要位于水动力弱、物质来源单一的环境。

Grain size analysis, parameter calculation and multivariate statistics have been carried out based on 533 surface sediments collected from the Hainan Island Offshore Area, and the range of the depth of locations is from 0 m to 174 m, and the average is 49 m. The major class of surface sediments of the research area is composed of -1Ф - 〉 11 Ф, and the key class, holding 55.62 %, consists of 6.0 - 9.0Ф. The sediments of the area can be divided into 9 types： gravel, sandy gravel, gravelly sand, sand, silt, silty sand, sandy silt, clayey silt, and sand-silt-clay. The content of gravel, sand, silt, and clay in the surface sediments is 1.14 %, 22.66 %, 52.50 %, and 23.70 %, respectively. The mean grain size of sediments in this area is -1.56 Ф - 7.57 Ф and the average is 5.87 Ф. The coefficient of sorting is 0.60 Ф - 3.72 Ф and the average is 2.24 Ф. Skewness is -0.35 - 0.77 and the average is 0.00. Kurtosis is 0.58 - 3.05 and the average is 1.01. There are two clusters based on R-mode cluster analysis of the grain size data： first cluster is composed of-1 Ф ~ 3 Ф, and second cluster consists of 4Ф - 〉 11Ф, situating coarser part and finer part in the frequent distribution curves. The grain size classes are well clustered and their feature is clear. The result of R-mode factor analysis shows that the eigenvalue of prior 4 factors is 92.80 %, and factor 1 is composed of minus loads of 0 Ф- 2 Ф and plus loads of 7 Ф - 〉 11 Ф. Factor 2 consists of plus loads of 5 Ф- 6 Ф. Factor 3 and factor 4 are composed of minus loads of 3 Ф - 4 Ф and -1 Ф, respectively. The coarse sediments of the area are mainly located in sedimentary environment with high hydrodynamic force and multi-plicate source of materials and often changed by modem granule sedimentation. The fine sediments often lie in sedimentary environment which is low-energetic and single in the source of materials.