Reconstruction of sea level fluctuation and environmental change in Khao Sam Roi Yot National Park, Changwat Prachuap Khiri Khan during the late holocene

Abstract

The Gulf of Thailand is generally provided the efficiency evidences of sea level fluctuation according to the lack of tectonic events. Sam Ro Yot National Park (SRY) is located in the west coast of the Gulf of Thailand with its elevation approximately at sea level. Sedimentary sequences from SRY wetland has been obtained. This sedimentary sequence can be divided into 3 units, comprised dark grey silty to sandy clay of unit A, beige clay of unit B, and gyttja sediment of unit C. An intensive analysis was focused on core CP-4 because it is the longest core and compose of all sedimentary units. Environmental reconstruction was accomplished by pollen analysis, grain size analysis, Loss on Ignition (LOI) and radiocarbon dating. This area was under intertidal environment and dominated by Rhizophora-mangroves since c. 3500 - 1700 cal year BP with a temporary dry conditions at c. 3300 cal year BP. Mangrove subsequently transferred to back mangroves at c. 1700 – 1600 cal year BP according to sea level regression. A minor transgression occurred later at c. 1600 – 1000 cal year BP, displaced this area by Avicenia-mangroves. Thereafter, mangrove zonation was prograde seaward due to the second regression, effected this area prominent by back mangroves at c. 1000 - 400 cal year BP. Freshwater wetland was finally replaced from c. 400 cal year BP to present.