江苏弶港JC-1203钻孔沉积物粒度特征及其古环境意义

选取江苏弶港地区JC-1203钻孔, 通过分析其岩性、沉积物粒度参数和概率累计曲线, 结合已有文献资料和测年数据, 将JC-1203钻孔0~50.00m段自上而下分为5个沉积单元(DU1、DU2、DU3、DU4和DU5). 研究表明: DU1段(0~4.00m), 中值粒径(Md)为3.40~4.94Φ, 平均4.31Φ, 分选系数(δ1)为0.94~1.82, 平均1.24, 粒度概率累积曲线由跃移?–悬浮两组分构成, 滚动组分缺失, 反映了MIS1末期研究区为潮坪相沉积环境; DU2段(4.00~27.39m), Md为1.96~4.87Φ, 均值3.30Φ, δ1为0.54~2.17, 均值1.25, 曲线形态为跃移?–悬浮两单元构成, 反映研究区MIS1中?–末期为潮流沙脊相沉积; DU3段(27.39~37.33m), Md为1.90~4.18Φ, 均值2.79Φ, δ1为0.54~2.24, 均值1.34, 曲线形态为跃移?–悬浮两单元构成, 反映研究区MIS1早?–中期为滨海相沉积环境; DU4段(37.33~45.54m), Md为4.14~6.79Φ, 均值6.00Φ, δ1为1.5~2.3, 均值1.8, 概率累积曲线形态复杂多变, 反映研究区MIS3中?–末期的陆相河流沉积环境; DU5段(45.54~ 50.00m), Md为3.18~6.40Φ, 均值4.94Φ, δ1为0.99~1.97, 均值1.67, 曲线形态以滚动?–跃移?–悬浮三单元构成为主, 反映研究区MIS3早期的浅海相沉积环境.

Grain size characteristics and their paleo environmental significance of JC-1203 core sediments in Jianggang of Jiangsu province

With JC-1203 core in Jianggang of Jiangsu province, the core sediments are collected to analyze their lithology, grain size parameters and probability cumulative curve characteristics. Combined with reference and dating data, the 0-50.00m segment of the JC-1203 core sediments can be divided into five units named as DU1-DU5 from top to bottom, and it is formed from MIS3. Based on the analytical results, the following conclusions can be reached: DU1 (0-4.00m): the distribution range of median diameter Md is 3.40-4.94Φ and the average is 4.31Φ, and the range of sorting coefficient δ1 is 0.94-1.82 and the average is 1.24. The grain-size probability cumulative curve is composed of the two parts of saltation and suspension components, and the rolling component is absent, which shows the depositional environment of tidal flat since late MIS1 in Jianggang of Jiangsu. DU2 (4.00-27.39m): the distribution range of median diameter Md is 1.96-4.87Φ and the average is 3.30Φ, and the range of sorting coefficient δ1 is 0.54-2.17 and the average is 1.25. The probability cumulative curve are composed of saltation and suspension components, which shows the tidal sand ridges facies during mid-late MIS1 in Jianggang area. DU3 (27.39-37.33m): the distribution range of median diameter Md is 1.90-4.18Φ and the average is 2.79Φ, and the range of sorting coefficient δ1 is 0.54-2.24 and the average is 1.34. The probability cumulative curve is composed of saltation and suspension components, which shows the littoral facies during early-mid MIS1 in the research area. DU4 (37.33-45.54m): the distribution range of median diameter Md is 4.14-6.79Φ and the average is 6.00Φ, and the range of sorting coefficient δ1 is 1.5-2.3 and the average is 1.8. The probability cumulative curve has a number of different types, which shows the fluvial facies during mid-late MIS3 in the research area. DU5 (45.54-50.00m): the distribution range of median diameter Md is 3.18-6.40Φ and the average is 4.94Φ, and the range of sorting coefficient δ1 is 0.99-1.97 and the average is 1.67. The probability cumulative curve is mainly composed of rolling, saltation and suspension components, which shows the neritic facies during early MIS3 in Jianggang area.