Spatial distribution and stratigraphic characteristics of surface sediments in Taihu Lake,China

A geophysical survey was carried out for Taihu Lake,one of the largest shallow lakes in China.The StrataBox Marine Geophysical Instrument was applied for the first time to obtain high-resolution seismic data (in the form of vectorgraphs) of the lake sediment.Data were then interpreted by SonarWiz.Map acoustics software.Data were correlated with core stratigraphy from the lake as well as an outcrop on the northern side of the lake at Yao Bay.Results show that the upper 10 m sediment (beneath the interface of the sediment and the overlying lake water) is characterized by laminated sediments,which can be classified into two stratal types,i.e.lacustrine sediment stratum (U1) and underlying hard loess stratum (U2).The contact of these two lithologies is not continuous,and part of it is absent in the lake basin.Unequally spread over the lake basin,the lacustrine sediment (mainly consisting of sludge and muddy-clay) is found in areas along the western bank,to the northwest of the Xishan Mountains and along the northwestern side of the lake.In the rest of the lake basin,the hard loess stratum is exposed in outcrops.The depth of the lacustrine sediment ranges from 1 to 2 m,while the depth of the sludge (closely related to the modern lacustrine environment) varies from 0.03 to 1.0 m.The spatial distribution of lacustrine sediments in Taihu Lake is primarily influenced by transportation and sedimentation of riverine materials,as well as the hydrodynamics of lake currents.