High resolution luminescence chronology of coastal dune deposits near Chumphon, Western Gulf of Thailand

The development of coastal dunes is linked to environmental controls such as sea-level variability, climatic conditions, and coastal morphology. Understanding the spatial and temporal variations of dunes is crucial for predicting how coastal landscapes may react to future climate changes and sea-level rise. However, there are very few detailed studies on the longer time-scale evolution (centennial to millennial) of coastal dunes from subtropical and tropical regions. Here, we combine a high-resolution luminescence chronology with sedimentological analyses to study the depositional history of a transverse coastal dune located within the Bang Berd dune field, Western Gulf of Thailand. While luminescence dating of uniform aeolian deposits is normally straight forward, we observe strong variations in the natural dose rate which are likely explained by the enrichment of accessory minerals in some laminae. Deposition of the dune started at least around 3000 years ago and coincides with a regional sea level drop. Sedimentary structures indicate deposition occurring predominantly in relation to the northeasterly winter monsoon. As the sea-level rise and increased storm intensity in the future may lead to stronger erosion along the coast, this study is highlighting the importance of the Bang Berd dune system as natural protection against coastal inundation

Multi-proxy approach to identify the origin of high energy coastal deposits from Laem Son National Park, Andaman Sea of Thailand

Understanding the frequency of high energy storm and tsunami events is crucial for apprehending the vulnerability of coastal communities. Identifying and dating sedimentary evidence deposited by such high energy events can assist in the planning and installation of suitable protection measurements. The Andaman Sea coast of Thailand is particularly vulnerable to such events as illustrated by the 2004 Indian Ocean Tsunami. Here, three shore-perpendicular transects and ten sediment cores along a beach ridge in the northern part of Lam Son National Park, Ranong Province, Andaman Sea coast are investigated with respect to high energy deposits. A multi-proxy analysis was conducted including stratigraphical correlations between cores, detailed description of physical characteristics, sedimentary structure, grain size, organic matter and carbonate content as well as identification of the remains of marine organisms. Optically stimulated luminescence (OSL) dating was applied for determining the age of the sediments on this beach ridge plain. The stratigraphy and sediment characteristics, in particular composition, of the sands in the study area clearly allow us to distinguish between high energy deposits and normal beach sediments. Two high energy deposits were identified and attributed to result from the 2004 Indian Ocean Tsunami as well as a past storm, which, based on OSL dating occurred more than 340 ± 20 years ago