粤东南澳-澄海海域晚第四纪沉积特征和沉积环境演变

通过对粤东南澳—澄海海域上第四系地层的沉积特征和年代学研究,结合陆区前人的资料,分析该区晚更新世以来的沉积环境演变特征。通过对钻孔资料的分析,将该区上第四系划分为3个沉积旋回,每个沉积旋回均具有由粗变细的沉积韵律,一般由砾砂或中粗砂开始,以淤泥或黏土结束。通过对该区不同层位14C年代测定和分析,认为该区第四系沉积开始于晚更新世中期,与韩江三角洲平原区开始接受沉积的时代一致,这表明二者是作为一个整体同时开始接受沉积的。该区前两个沉积旋回形成于晚更新世,第三旋回形成于全新世。全新世后海平面波动对该区的影响并未像对内侧平原那么明显,说明该区进入全新世后沉积环境趋于稳定,相对变化较小。

Late Quaternary sedimentological characteristics and sedimentary environment evolution in sea area between Nan'ao and Chenghai, eastern Guangdong

The sedimentological characteristics and sedimentary environment evolution in the Late Quaternary in the sea area between Nan'ao and Chenghai of eastern Guangdong province are studied based on the analysis on 12 boreholes and chronological researches.Three sedimentary cycles were identified according to the borehole data.Each cycle shows a feature of upward-fining sequence,normally starting with coarse-medium sand and ending with silt or clay.Chronological data were obtained by 14C dating with the samples from the beds of difference cycles.It is demonstrated that the Quaternary sediments started depositing in the Late Pleistocene,which was coeval with the deposits of the Hanjiang River Delta.The dating results also indicate that the first two cycles were formed in the Late Pleistocene,while the last one was in the Holocene.The influence of sea level change on this sea area since the Holocene was relatively minor compared with the inner plain where two transgression/regression sequences were recorded,indicating that the sedimentary environment in the research area has been relatively stable since the Holocene.