Diatoms and their palaeoenvironments from the cores of Xijiang Delta in China

Sedimentary diatoms of Cores ZXZ1 and ZXZ2 collected in the Xijiang Delta were studied.Total of 168 species and variants of diatom species belonging to 48 genera were identified; six bands of Core ZXZ1 and five bands of Core ZXZ2 were classified based on adiatom species property.And stratigraphic subdivision and a correlation analysis were made according to diatomanalysis together with grain-size data and ¹⁴C year data, It is found that 0~11.35 m (including Ⅳ,Ⅴ,Ⅵ diatom bands) of Core ZXZ1 belonged to the Holocene sedimentary, 11.35~35.6 m (including Ⅰ,Ⅱ,Ⅲ diat om bands) belonged to the Late Pleist ocene sedimentary; 0~9.9 m (including Ⅲ, Ⅳ,Ⅴ diatom bands) belonged to the Holocene sedimentary, 9.9~33 m (including Ⅰ, Ⅱ diatom bands) belonged to the Late Pleistocene sedimentary.The sedimentation and environment since Pleistocene have been discussed.Results showed that at the Late Pleist ocene Core ZXZ1 was in marine sedimentary environment, and Core ZXZ2 was in land sedimentary environment; at Holocene the two core were all in marine sedimentary environment.The different sedimentary environments at the Late Pleistocene were mainly due to vertical motion of fault block.