Vegetation dynamics and sea-level changes in the upper gulf of Thailand

Abstract

Climate change plays a role in sea level fluctuation, either transgression or regression leads to coastline evolution. Samut Sakhon province is located on the coast in the upper Gulf of Thailand therefore past sea-level studies in this area can contribute information to a better understanding of sediment dynamics and assess future coastline development. The study site provides sedimentary sequences consisting of 9 sediment units from 25.5-7.2 m. DBS, results of LOI, Ti/Ca, and Zr/Rb ratio, grain size, and pollen analysis were interpreted together with radiocarbon dating to reconstruct past environments in the study site. The past environment in Samut Sakhon site can divided into two parts in the late Pleistocene (26.5-22.7 cal ka BP), Samut Sakhon was temporal exposure during dry conditions, and in the mid/late Holocene (5.4-1.1 cal ka BP), mangrove forests grew due to sea level transgression at 5.4-4.4 cal ka BP before being transferred into the back-mangrove forest at 4.4-4.2 cal ka BP and wetland during sea level regression at 4.2-2.3 cal ka BP, respectively. Samut Sakhon site was likely to be a brackish area thereafter at 2.3-1.1 cal ka BP. To improve the level accuracy and decrease data discrepancies, autonomous level monitoring, and differential global positioning systems should be used in combination with future research.