【摘要】 南海北部长湾贝壳堤是一典型的风暴潮成因贝壳堤。该贝壳堤的横向、纵向露头和钻孔所显示的地层结构、层理特征、粒度特征、14C测年、物质组成、贝屑种属生境及当地风暴增水高度和地壳升降幅度表明:①贝壳堤由风暴沉积组成,是风暴潮增水期间海岸沉积物堆积的结果,由于堆积在平均高潮面之上,增水退却后不受正常天气下波浪的影响得以保存;②理想剖面由下而上分4个部分:潮滩堆积、激浪带堆积、增水面下波浪堆积和增水面上波浪爬高堆积,各个部分具有不同的沉积特征,分别代表贝壳堤向上增长的各个阶段的沉积环境和风暴作用方式;③风暴潮贝壳堤与非风暴潮贝壳堤不仅在发育过程,而且在沉积结构、粒度特征、贝屑种属、堆积部位、堆积高度及环境意义等方面都有所不同。更多还原

【Abstract】 Changwan Chenier along the southern coast of South China is a typical chenier built up by big storms. The horizontal and vertical exposures of the chenier,and stratum structures,granularity features,14C ages,material composition and shell species’s ecological environment,along with storm surge levels and earth movement of the study area have been analyzed.The study indicates that the storm deposits of the chenier can be well preserved because they are mainly located above the mean high water level due to accumulation under big storm surges and therefore will not be affected by fair-weather waves.The sequence can be upwardly divided into 4sectors with different sedimentary characteristics and profile features,representing the 4phases from the beginning to the end of the chenier development.The 4 phases are(1)formation of a tidal flat with black silt;(2)storm deposition in a surf zone characterized by hummocky cross-stratifications;(3)storm deposition under surge water represented by scour-and-fill structures with a swell profile;(4)swash deposition over surge water with no clear beddings.A storm building up chenier is different from a no-storm origin chenier not only in the development processe but also in sedimentary structures,shell species and depositional locations and elevations,and environmental significance.更多还原