Sedimentary sand bodies of shallow-water delta has become one of the main target areas of the current exploration.Thus a further study on sedimentary evolution and distribution of sand bodies of shallow-water delta should be of great importance for exploration.The 4

th

member of Cretaceous Quantou Formation in Linjiang area provides an interesting example to study sedimentary evolution and distribution of sand bodies of shallow-water delta during the stage of lake transgression in detail.The work is based both on previous research and on a combination of cores

well logging and seismic data.The results show that delta plain and delta front are still the main component of retrogradational shallow-water delta

whose sediment grain size becomes gradually finer upwards

and the color of mudstone component shifts from aubergine to celadon controlled by short-term fluctuation of sedimentary water.With rise of lake water level

sedimentary facies boundaries moved quickly towards land.However

this movement is superimposed by multiple shorter-term fluctuations of lake level and bi-directional migration of facies boundary

and the channel sandstones can form quite some distance away from lake shore.As the main type of sand bodies of retrogradational shallow-water delta

the size of channel sandstone reduced gradually during lake transgression

showing increasing thinning of sand thickness upwards.The channels terminate as distributary sheet sands

reformed by infra-littoral wave.On the plane view

the cycles of channel development become fewer from proximal to distal.Channel sandstone of delta plain and nearshore delta front

which mainly developed before large-scale lake transgression

is favorable targets for oil-gas exploration.