tailieunhanh - Báo cáo " Characteristics of Quaternary sedimentary facies in relation to water bearing capacity of aquifers and aquicludes in the Red River Delta, Vietnam "

There are five Quaternary sedimentary sequences in the Red River Delta, Vietnam. The forming of each sequence is related to transgression and regression phases. The sequences, which was formed in transgression period, composed mainly of fine grained size leading to the water bearing capacity is very low and plays a role as aquicludes. Besides, in these fine grain size layers, the contents of arsenic and iron are high, especially in dark clay, silty clay rich in organic material . | VNU Journal of Science Earth Sciences 23 2007 170-176 Characteristics of Quaternary sedimentary facies in relation to water bearing capacity of aquifers and aquicludes in the Red River Delta Vietnam Nguyen Thanh Lan Tran Nghi Dang Mai Dinh Xuan Thanh College of Science VNU Received 07 March 2007 Abstract. There are five Quaternary sedimentary sequences in the Red River Delta Vietnam. The forming of each sequence is related to transgression and regression phases. The sequences which was formed in transgression period composed mainly of fine grained size leading to the water bearing capacity is very low and plays a role as aquicludes. Besides in these fine grain size layers the contents of arsenic and iron are high especially in dark clay silty clay rich in organic material of swamp facies and brown dark brown clay of flood facies so that they are stated as a source of arsenic contamination in the groundwater. For the sequences formed in regression period composed mainly of gravel cobbles pebbles and coarse sand of fluvial river channel facies are good aquifers. These aquifers are the main supply sources for human activities in the Red River Delta. Keywords Aquiclude Aquifer Red River Delta Sedimentary facies. 1. Introduction Like many cities and provinces of Vietnam the provinces in the Red River Delta receive water supply from groundwater in Quaternary sediments. The characteristics potential and variation trend of this water resource depends much on the distribution of sedimentary facies in the stratigraphic column. The depositional environment and material composition express different paleogeographic environments such as marine continental environment or transitional environment. In the Red River Delta area the facial association rule is examined in Corresponding author. Tel. 84-4-5587059. E-mail lannt@ three spatial directions vertical perpendicular and parallel with the present coastline. 2. Characteristics of Quaternary sedimentary sequences In .