Distinguishing Late Holocene Storm Deposit From Shore-normal Beach Sediments From the Gulf of Thailand

Abstract

Grain size, as one of sedimentological proxies, coupled with a detailed description of the sedimentary structures and luminescence dating were used to unveil the sediment sources and transport process of the Holocene ancient coastal storm events recorded in the beach ridge plain, wet swale and muddy environments at Prachuap Khiri Khan, in the Southern Peninsula of Thailand. In this study, a total of 141 sand samples were collected from the shore-normal ridge-swale topography and analyzed for layers of candidate storm deposits, revealing at least 21 candidate coastal storm events. The grain size distribution of beach sediments was, in general, unimodal, while the candidate storm sediments revealed a mixed combination of multimodal, bimodal and unimodal distributions. Plots of mean grain size against skewness and kurtosis and of skewness against kurtosis could differentiate storm deposits from shore-normal beach sediments. Sedimentary structures preserved in the ancient coastal storm deposits included parallel and inclined landward laminations, mud rip-up clasts, layers of shell fragments, a pebble grain, normal and reverse grading and sharp lower and upper contacts. Candidate storm layers overlain on a dry beach ridge intervened with mud in a swale showed a finer and thinner landward deposit. Marine shell fragments, smaller foraminifers, ostracod and scaphopod (tusk shell), were well preserved. Based on optically stimulated luminescence dating and a correlated accelerator mass spectrometry age, multiple layers of sand derived from different frequencies of coastal storms were deposited over the middle to late Holocene.

Barrier Island Sediments Reveal Storm Surge and Fluvial Flood Events in the Past Centuries at Thua Thien Hue, Central Vietnam

“…The parallel-laminated, inclined-laminated sand, and normal and reverse grading found in Units II, IV, and VI (Figures 3, 7) are additional important evidence of storms, similar to previous studies (Leatherman and Williams, 1983;Sedgwick and Davis, 2003;Phantuwongraj et al, 2013;Kongsen et al, 2021). However, although foreset bedding, which is often recognized in storm deposits (Nanayama et al, 2000;Phantuwongraj et al, 2013;Kongsen et al, 2021), was not observed in the storm deposit of this area, the presence of laminated sand indicates wave pulses that carried sediments that were then deposited after the dissipation of each pulse.…”

“…A handheld GPS was used to provide reference points of all stations. The accuracy of distance measurement using the fine average measurement mode with a prism was ± (2 + 2 ppm X D) mm (Kongsen et al, 2021). Tidal ranges of the area were established, including the mean tide, high tide, and low tide, by converting elevation into meters amsl, following the method of Williams et al (2016).…”

“…This might indicate the flowing of storm waves and tackling of sediments by surge pulses in the time of deposition associated with local topography, shear velocity, and size of sediment (Bridge, 1978(Bridge, , 1984 that developed from an upper flow regime and an upper plane bed (Allen, 1984;Cheel, 1990;Fielding, 2006). In addition, MRCs in the storm layer (Units VII, IV, and II) reflect the flowing of storm waves under shear stress and frictional force, eroding preexisting layers and redepositing them with clasts of finergrained sediment (Williams et al, 2016;Kongsen et al, 2021).…”

“…The often reported characteristics of storm deposits preserved in coastal areas include sharp and erosional contacts, normal and reverse grading, mud rip-up clasts (MRCs), mud laminae, laminated sand, marine shells, marine fossils, and marine microfossils (e.g., Fearn, 1993, 2000a,b;Donnelly et al, 2001;Liu, 2004Liu, , 2007Donnelly, 2005;Elsner, 2007;Morton et al, 2007;Williams, 2010Williams, , 2013Phantuwongraj and Choowong, 2012;Phantuwongraj et al, 2013;Williams et al, 2016;Kongsen et al, 2021). In contrast, FFDs can usually be identified by sharp and erosional contacts, lamination, cross-bedding, massive mud contents, wellsorted suspended sediment with a rounded shape due to long-distance transport, and a high organic matter (OM) and plant detritus content (e.g., Rubin et al, 1998;Zhu et al, 2005;Yamashita et al, 2011;Khan et al, 2013;Day et al, 2016;Matsumoto et al, 2016;Yamada et al, 2016).…”

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

“…1C and 2C-E). The topographical measurement was conducted by using a total station survey camera SOKKIA (SET630R) together with providing reference points of all stations by a hand-held GPS (Kongsen et al, 2021a;b). The obtained topographic values were then referenced with the tide table of Khura Buri tide gauge station for the time of measurement (Fig.…”