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Map of the new Hong Kong Airport site showing the distribution of boreholes where samples were taken for radiocarbon dating.

Map of the new Hong Kong Airport site showing the distribution of boreholes where samples were taken for radiocarbon dating.

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Radiocarbon dating is used widely for the reconstruction of late Quaternary sea-level changes. In the present study, eight case studies in Hong Kong have been chosen to highlight the difficulty in obtaining reliable radiocarbon dates. Pre-Holocene radiocarbon dates exceeding about 8100yrBP have been found to show a young age bias. A shell sample da...

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... the new Hong Kong Airport site at Chek Lap Kok ( Fig. 1), nine plant fragments were taken from eight boreholes located in Fig. 2 for accelerator mass spectro- metry radiocarbon dating (RMP Econ. Ltd., 1982). The stratigraphy of the boreholes is shown in Fig. ...

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... These studies always consider younger ages to be more acceptable ages and then discuss the reasons for older ones. However, depositional processes may result in underestimated ages by OSL dating (Nian et al., 2022) and plant radiocarbon dating can be younger because of the post-depositional introduction by plant rootlets or other processes (Yim, 1999), which indicate the younger ages may not be the more reliable ages. ...
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... Although the highstand transitions are diachronous from subaerial to subaqueous deltas, the ca 7.5 ka BP could provide a reasonable time point based on previous reconstructed shoreline or sea-level histories and numerical simulation results (Fig. 8A) Fig. 9. Isopach maps of (A) the Holocene, (B) Holocene transgression and (C) Holocene highstand thicknesses throughout the whole Pearl-derived dispersal system (Pearl River Delta, Lingdingyang Bay, proximal subaqueous clinoform and distal mud belt). Some thickness data are digitized from previous sediment cores (data shown in Table S1) (Huang et al., 1983(Huang et al., , 2018Li et al., 1984Li et al., , 1990Feng et al., 1990;Zang et al., 1990;Chen et al., 1994Chen et al., , 2015Chen et al., , 2016Chen et al., , 2019Yang, 1994;Xu & Feng, 1997;Davis, 1999;Fyfe et al., 1999;Yim, 1999Yim, , 2001Yang et al., 2003Yang et al., , 2010Yim et al., 2004Yim et al., , 2006Huang & Cai, 2007;Huang & Yim, 2007;Lan et al., 2008;Wang, 2008;Wang et al., 2009;Zong et al., 2009aZong et al., , 2010Zong et al., , 2012Zong et al., , 2013Chen, 2010;Tang et al., 2010;Wei, 2010;Zhang et al., 2010Zhang et al., , 2020Wei & Wu, 2011;Cao et al., 2012;Dong et al., 2012;Liu et al., 2012;Guo et al., 2013;Zhao et al., 2013Zhao et al., , 2014Zhao et al., , 2016Peng et al., 2014Peng et al., , 2021Xie et al., 2014;Shi et al., 2015;Wei et al., 2016;Yin et al., 2016;Yu et al., 2016;Zheng et al., 2016;Xiong et al., 2018a;Lee et al., 2019;Lu et al., 2020;Pei, 2020;Fu et al., 2020a,b;Hao et al., 2021;Ping et al., 2021;. Locations of the referenced cores are shown by black dots (partly shown in Fig. 1). ...
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... Previously published ages in the PRD mostly relied upon the radiocarbon ( 14 C) dating method (Huang et al., 1982;Zong et al., 2009b;Hu et al., 2013;Wu et al., 2017;Fu et al., 2020). However, the 14 C dating may encounter some problems in estuarine-deltaic deposits, such as reworking or contamination of carbon material due to the frequent change in hydrodynamics and sedimentary environments (Yim, 1999;Kong et al., 2014), and carbon reservoir effect (Xu et al., 2020), especially in the carbonate-rich Pearl River region (Liu et al., 2017). These problems can probably lead to abnormal ages. ...
... This means that the OSL dating yields ages directly associated with sedimentation process of wellbleached sediments which have been examined in many deltas, e.g., the Yangtze delta by Nian et al. (2018b), the PRD by Xu et al. (2020), and the Thu Bon River delta (Vietnam) by Qiaola et al. (2022). In the high-energy hydrodynamic PRD estuaries, 14 C samples like death shells might be subjected to reworking during their source-to-sink transportation (Yim, 1999), which is evident from the fact that most of the shell samples in this study were broken. Reworking of shells leads to biases in 14 C ages, e.g., age overestimation due to old reworked-carbon introduction Nian et al., 2018a,b;Qiaola et al., 2022) and age underestimation caused by inclusions of younger reworked shell (Yi et al., 2012). ...
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... The Pearl River Estuary (PRE), located in the south of China, has been formed since the Late Pleistocene (Liu et al., 2013;Zong et al., 2009aZong et al., , 2009b. Its Late Quaternary sedimentary succession is significantly influenced by sea-level change and generally records three marine transgression cycles (Yim, 1999). The multiple transgressions of the seawater in the Quaternary have caused the formation of an aquifer-aquitard multilayer system between the interbedded river and marine sediments, allowing groundwater conserved in the estuarine strata. ...
... Most studies of sea-level changes from Hong Kong waters have concentrated on abundant data available from borehole investigations (Yim, 1984(Yim, , 1999) and on high-resolution seismic analysis (Fyfe et al., 1997). Sea-level histories derived from such studies have not discovered any evidence of higher sea-level stands during the Holocene as these studies have concentrated on offshore sediments and their resolution may be insufficient for such studies. ...
... Sea-level histories derived from such studies have not discovered any evidence of higher sea-level stands during the Holocene as these studies have concentrated on offshore sediments and their resolution may be insufficient for such studies. Dismissing the earlier work of Berry (1961), Meacham and Yim (1983) and Yim (1984Yim ( , 1999 suggest that there is no evidence from Hong Kong waters for oscillating Fig. 2. Photograph of the Saccostrea cucullata fossil sample location on the southern side of Big Wave Bay, Hong Kong Island at very low tide. The fossil oysters come from a 20 cm thick horizon located in the shadow underneath the prominent overhanging slab. ...
... Holocene sea-level curves or for higher late Holocene sea-levels. Yim (1999) regards the present day sealevel as having been attained approximately 6000 yr BP and remained static at this level since then. This interpretation notwithstanding the geomorphic features recognised by Berry (1961) clearly exist although their recognition is becoming more difficult with time as urban and industrial development of Hong Kong exploits them. ...
... Sinha et al. 1996), variação de nível do mar (e.g. Yim 1999) e reconstruções de paleoclima e paleovegetação (e.g. Coe et al. 2014)]. ...
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... The main criticism of the papers dealing with MIS3 highstands is associated with the limitations of the radiocarbon as a geochronological tool. Indeed, a significant part of the MIS3 interval cannot be dated with confidence beyond cal BP 45,000, and contamination of older materials with young carbon can result in apparent MIS3 ages (Murray-Wallace et al. 1993, Yim 1999, Hanebuth et al. 2006). On the other hand, the introduction of the Accelerator Mass Spectrometry (AMS) technique to radiocarbon dating (Dorn et al. 1989) brought another perspective to the original chronology limitation of cal BP 30,000 years. ...
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... Coastal sediments of the MIS 3 interstadial are commonly dated using the AMS 14 C method, but the reliability of dating results is questionable because of extreme sensitivities to contamination potentially introduced during burial, sampling, and/or laboratory processing of dating materials (d' Errico and Sánchez Goñi, 2003;Jull and Burr, 2006;Pigati et al., 2007). This apprehension has led some researchers to reinterpret MIS 3 interstadial deposits as MIS 5 (Yim, 1999;Hanebuth et al., 2006;Zong et al., 2009;Yi et al., 2012;Isla and Schnack, 2016). Other lines of evidence for age reinterpretation include additional age data by luminescence, uranium-series and other dating methods, and reconstructed MIS 3 sea-level elevations that are much higher than those from dated coral-reef sequences and oxygen-isotope records from deep-sea core sediments (Chappell et al., 1996;Yokoyama et al., 2001;Siddall et al., 2003). ...
... A few penultimate transgression sequences that were originally dated within MIS 3 14 C ages, has been reassigned to MIS 5 transgression deposition based on U-series or OSL dates (Yim et al., 1990;Yi et al., 2012). Together with indirect evidence that a maximum highstand of MIS 3 sea-level should not exceed 40 m BPSL (below present sea level) according to dated coral-reef sequences and the oxygen-isotope record of deep-sea core sediments (Chappell et al., 1996;Yokoyama et al., 2001;Siddall et al., 2003), the elevated MIS 3 sea-level dated by radiocarbon has been questioned or rejected by some researchers (Yim, 1999;Hanebuth et al., 2006;Zong et al., 2009;Isla and Schnack, 2016). ...
... High degrees of weathering and oxidation make it difficult to accurately date paleosols. Poor age constraints lead to protracted debates on the initial timing of the first paleosol formation, MIS 3 (e.g., Li et al., 2002;Chen et al., 2008;Wang et al., 2013) or MIS 5 (e.g., Yim et al., 1990;Yim, 1999;Zong et al., 2009). One plant-fragment sample from DU4 was dated at~38 cal kyr BP (Fig. 7). ...
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We present a history of late Quaternary coastal evolution based on the study of a 41.9-m-long sediment core from the Oujiang Delta. Multiple analytical methods are employed, including sedimentary facies analysis, radiocarbon dating, and the investigations of grain size, elemental, microfossil and pollen compositions. Two transgression-regression sequences, separated by a paleosol layer, are identified. Several lines of evidence indicate that the lower sequence was deposited during the mid-early MIS 3 stage, under a relatively warm and wet climate. An elevated MIS 3 highstand sea level (higher than -24m) is observed. The upper sequence was created after the paleosol was flooded during a marine transgression at ∼9.5calkyr BP. Seven weak East Asian Summer Monsoon (EASM) events are identified with central years of ∼8.4, 7.7, 6.3, 5.7, 4.7, 2.8 and 1.8calkyr BP. These coincide with those from the ECS sediment cores and the Dongge Cave δ¹⁸O record, indicating that EASM precipitation is a major controlling factor of sedimentation rates in the region. The Oujiang Delta is also subject to typhoon impacts and East Asian winter monsoon (EAWM)-induced coastal currents. Active typhoons and a relatively enhanced EAWM occurred during the weak EASM period between 4.9 and 6.4calkyr BP, producing high sedimentation rates in the middle Holocene. We emphasize the high sensitivity of small Asian river deltas as archives of the EASM, EAWM and typhoons. Such environments merit further as a means to understand past changes as well as future responses to projected climatic and sea-level change.
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... Compared the residual content of radiocarbon 14 of samples with that of present similar samples, we could deduce the epoch from the time after exchanging 14C. As the half-life period of 14C is 5568 years, it will be reduced by about 1,000 times after 10 half-life periods [2,6,15]. So the modern radioactive detector almost cannot work. ...
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Since late Quaternary, the intense change of coastal sedimentary environment in the Pearl River Delta (PRD) region has resulted in accumulating the thick sedimentary layers with the different causes and properties which were influenced by the fluctuation of sea levels, the change of ancient climate and human activities. Based on the interpretation of high resolution of these sediments, such as the period, sedimentary facies and discontinuous faces, we can infer the evolution of the ancient climate of regional Quaternary environment in the background of global change to know more details about the formation of the PRD. Taking the Xilin Hill fault as the example, we explained the reason of the PRD formation, inferred its interactions with local/regional climate and sea-level changes, and analyzed the evolution of the PRD formation and its controlling factors of the coastal sedimentary environment by using 14C dating technology. It is noted that the neo-tectonic movement and the fault activities played a critical role in controlling coastal geological environment. This is helpful to further investigate the evolution of the PRD coastal sedimentary environment, the history of inversion region, and the sedimentary facies model of the interaction between land and sea. More investigations will be conducted in the near future.