... formed in transgression period, composed mainly of fine grained size leading to the waterbearingcapacityisverylowandplaysaroleasaquicludes.Besides, in thesefinegrainsizelayers, the contentsofarsenicandironarehigh,especially in darkclay,siltyclayrich in organic ... corresponding with the fifthdepositionalcycleofThaiBinhFormation. In spatial distribution, the sediments of the first and second sequences are ratherwidespread in the plain. The thirdsequencehasa ... in the central part passing intosiltyclayofflood plain, oxbow,coastalswampandpeatfacies in the directionfrom the plain to the modern coastline. The fourth sequenceconsistsofswampclay,lagoonalclayandpeat. In the directiontowards the centerof the plain,eachofthesesequencesappearsmoreandmoreparticular...