海南岛东部铜鼓岭岸段港湾岸滩沉积特征

海南岛东部铜鼓岭岬角南、北两侧的淇水湾和月亮湾海岸海滩均为中粗砂海滩,其中值粒径和平均粒径主要分布在0~2 Ф之间,反映了海南岛东部动力作用整体较强。月亮湾近岸20 m水深处沉积物的中值粒径主要分布在-1~-3 Ф之间,主要以砾石为主;10~20 m水深处沉积物中值粒径分布在-1~0 Ф之间,以极粗砂为主;铜鼓岭南部淇水湾,以粗砂为主,部分区域出现细砂,反映海滩受到的动力条件不如北部月亮湾海岸海滩显著。造成这种差异的主要原因是铜鼓岭岬角对东北向(主风向)风浪的阻挡和岬角南部港湾有宽广的珊瑚礁平台对波浪的消能。而且,淇水湾海岸北部和南部也有差异,北部珊瑚礁平台受到破坏,对波浪的消浪较弱,从而表现同一海滩滩面物质分布的南北差异。

Sedimentatary Characteristics of Rocky Embayment Coast in Tongguling in East of Hainan Island

Through the field investigations such as geological and geomorphology survey, beach and seabed bathymetry, beach profile measurements, grain-size analyses of the sediments of the beaches and seabed, this paper makes some preliminary conclusions as follows:(1) The sands of the Yueliang Bay and the Qishui Bay are coarse-middle sands and medium and mean grain-size diameters are mainly between 1-2 Ф.The grain-size results of beach and seabed sediments indicate that the wave is great in the Yueliang Bay and the Qishui Bay in the eastern Hainan Island.The reason is that the Yueliang Bay and the Qishui Bay face the sea directly and have no barriers, so the wind wave is stronger, which is influenced distinctly by winter and summer monsoon.(2) The coastal geomorphology have great influence on dynamicical condition and sementation environment.The medium grain-size of the seabed sediments is -1--3 Ф near 20-m fathom line, and -1-0 Ф between 10-20 m fathom lines, which shows that the wave function the sea bed at 20 m depth in the Yueliang Bay.However, there are coral reefs in the Qishui Bay, which can remove some energy, so the swash wave is not stronger than that in the Yueliang Bay.(3) Moreover, the different geomorphologies in the same embayment coast result indifferent dynamic conditions.Because of the coral reef damaged in the northern Qishui Bay, the coarse sizes of the sand in the sand beach are distributed in the different parts, which indicates swash wave acts frequently in the different tides, but in the southern Qishui Bay, only at the big tide time, the swash wave can act on the beach.