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• Reconstructed four mouth bars' (MB) development history of the West Pearl River. • Hydrodynamic conditions in Pearl Delta allow MB to form from 16 m water depth. • Natural vertical MB growth duration varies between 2800 and 2000 years. • Duration is inversely related to natural depositional rate from 2.7 to 5.7 mm/a. • Sediment supply and antecedent landscape are controlling factors. River mouth bars' formation is a key process of the delta development and river bifurcation, but details of the long-term developmental history of mouth bars and their role in the delta evolution are substantially less well documented. To characterize deltaic mouth bars' development, this study investigated the Sixianjiao, Jun'an, Da'aosha and Denglongsha mouth bars formed successively along the main course of the West Pearl River. The detailed lithological analyses of sediment cores indicate that the mouth bar sediment is characterized by its sandy nature with mud laminations or lenses and poorly preserved foraminifera. The onset of mouth bar sedimentation is affected by water depth. The Sixianjiao and Jun'an mouth bars initiated at shallower water depth (8.0 m and 11.0 m, respectively) due to the restrictions of higher basement landforms. In an area where water is deeper, the mouth bar development would begin only with the site being elevated up to about 16.0 m water depth, such as a case in Da'aosha. The duration between their onset and end of vertical growth varies between 2000 and 2800 years, which is inversely related to their sedimentation rates between 2.7 and 5.7 mm/a, indicating the importance of sediment supply. In addition, the locations of the four mouth bars were to some extent determined by the antecedent landscapes. Finally, the ages of these four mouth bars show a chronological order from land to sea, reflecting seaward delta progradation, contrary to previous morpho-dynamical numerical model's predictions. Our reconstruction of the West Pearl River mouth bars' developmental history provides a new insight into the geomorphological evolution of the Pearl River delta, a special delta developed within a complex estuarine bay. [ABSTRACT FROM AUTHOR]

This study has collected and analyzed seven sediment cores from the Pearl River delta, from which 16 new and high-quality sea-level index points are generated using a new approach. This study has also re-checked and re-calibrated the previously published sea-level data from China's southeast coast with corrections made for tectonic subsidence and sediment compaction factors. These sea-level data indicate a rise of relative sea level from −49.3 ± 0.8 m to the present height between 10,500 and 7000 cal. a BP. This sea-level history is similar to those recorded from other far-field locations and ice-volume equivalent sea-level models. The early to early-middle Holocene sea-level history in the study area shows a phase of accelerated rise at a rate increasing rapidly from 16.4 ± 6.1 mm/a at 10,500 cal. a BP to 33.0 ± 7.1 mm/a at 9500 cal. a BP. This phase was followed by a period of rapid decrease in the rate of sea-level rise to 8.8 ± 1.9 mm/a at 8500 cal. a BP and 1.7 ± 1.3 mm/a at 7500 cal. a BP. During the past 7000 years, the relative sea level in the study area changed very little. This new and complete history of Holocene sea-level change supports the following findings: (1) no obvious higher-than-present sea-level highstand in the Holocene is found from the northern South China Sea; (2) certain proportion of the effects of the predicted glacial isostatic adjustment were cancelled out by the effects of the weak upper mantle viscosity in the study area; (3) meltwater pulse 1b likely exists spanning into the early Holocene; (4) there are significant misfit between sea-level data and glacial isostatic adjustment models, and a revision to the existing ice melting history for the early Holocene is possibly needed. [ABSTRACT FROM AUTHOR]

In order to examine relative sea-level responses to the postglacial ice-volume change and the glacio-hydro isostatic adjustments (GIA), this study investigated the inner part of the Hangzhou Bay, east China, a tectonically relatively stable far-field location, and reconstructed the early to middle Holocene sea-level history. This investigation has established the elevational relationship between modern saltmarsh-mudflat and tidal levels based on diatom analysis for sea-level indicative meaning estimates, produced 17 high-quality sea-level index points, and simulated GIA processes for the study site. These results reveal that the relative sea level rose from −38.3 ± 1.6 m in c. 10,000 cal a BP to the present height by c. 7000 cal. a BP, and the average rate of sea-level rise decreased gradually from 19.6 ± 2.6 mm/a to 2.3 ± 1.5 mm/a during the 3000 years. This period of sea-level history was punctuated by two episodes of accelerated rise around 8200 and 7500 cal a BP. The relative sea level rose to 0.8 ± 1.4 m above msl by c. 6500 cal. a BP, followed by a gradual fall back to the present height at 4500 cal a BP, implying a different response to the potential additional ice melting between 7000 and 4000 cal a BP. A comparison of the sea-level histories between the inner and outer Hangzhou Bay indicates the coastal levering effect due to the marine inundation of the continental shelves. A further comparison between sea-level data from China and Malay Peninsula reveals different GIA effects between the Cathaysia-Yangtze Blocks and the Sundaland Block. • A modern analogue between diatom zones and tide levels. • RSL rose from −38.3 ± 1.6 m in 10,000 cal a BP to present height by 7000 cal a BP. • Punctuated by two episodes of accelerated rise around 8200 and 7500 cal a BP. • Evidence of coastal levering during the early Holocene. • Different GIA responses of Cathaysia Block and Sundaland Block to IESL. [ABSTRACT FROM AUTHOR]

This study was conducted to (1) investigate a former mangrove wetland on the east coast of Peninsular Malaysia near Kuantan and produce new sea-level index points (SLIP), and to (2) re-analyzed the modern vegetation and pollen results from a mangrove-swamp transect within the nearby estuary to establish the relationship between vegetation zones and tidal levels for estimating indicative meanings (IM) for the SLIPs. The results indicate that the modern floral and pollen zones match well with the fossil ones, and four IMs were appropriately established. Combining with the recently published SLIPs from Terengganu, the 15 new SLIPs from Kuantan were used to reconstruct the middle-to-late Holocene relative sea-level (RSL) history for the east coast of the Malay Peninsula. This history shows that the RSL reached c. 1.5 m msl around 6500 cal. a BP and rose to c. 2.0 m msl by 4500 cal. a BP. This phase of RSL rise in this far-field site supports the hypothesis that additional ice melting occurred between 7000 and 4000 cal. a BP. During this phase of RSL rise, erosion and redeposition of estuarine sediments occurred at the study site. Since 4000 cal. a BP, the RSL fell gradually to below the present height by 800 cal. a BP. In general, this RSL history matches well with the GIA model with the ICE4G melting history. Furthermore, the SLIPs from the east coast are systematically lower in elevation than those recorded in the west coast. The difference is about 1.5 m in the beginning of the middle Holocene and it decreases gradually towards the late Holocene. This difference, thus, implies the existence of continental levering during the Holocene. • Indicative meanings for sea-level index points generated from a modern mangrove transect. • New mangrove-based sea-level index points generated from the east coast of the Malay Peninsula. • RSL reached 1.5 m by 6500 cal. a BP and 2.0 m by 4500 cal. a BP, implying continuous ice melting from 7000 to 4000 cal. a BP. • Relative sea level fell from 4000 cal. a BP to below the present height by c. 800 cal. a BP. • RSL in the early mid-Holocene in the east coast was 1.5 m lower than that in the west coast, implying continental levering. [ABSTRACT FROM AUTHOR]

Abstract This study has reconstructed the Holocene relative sea-level history in the relatively tectonically stable Malay Peninsula with two specific objectives: quantifying the sea-level indicative meanings of mangrove sediments and producing new high-quality sea-level index points. In this study, a wetland on the east coast of the Peninsula was extensively surveyed; the elevational relationship between habitat zones and their pollen and diatom assemblages was established; and a number of indicative meanings were precisely quantified for this wetland. This quantified relationship is extrapolated to other coastal sites of the Peninsula for re-calibration of previously published mangrove-based sea-level data. The reconstructed sea-level history from the new and re-calibrated data demonstrates a period of rapid sea-level rise at a rate of 15.8 ± 3.9 mm/a between 10,500 cal a BP at −35.0 ± 4.3 m and 9000 cal a BP at −14.2 ± 1.6 m. The rate of rising sea level was gradually reduced to zero from 9000 to 5000 cal a BP, and by the end of this period the relative sea level reached a highstand of c. 3.3 ± 0.2 m. Over the past 5000 years relative sea level fell to its lowest point at −0.6 ± 0.1 m by 800 cal a BP. This far-field sea-level history has been driven by the global ice-volume change and glacial isostatic adjustment, and it matches well with the modelled ice-volume equivalent sea level. Highlights • Indicative meanings for sea-level index points from mangrove wetland habitats of Peninsular Malaysia are quantified. • A set of high-quality sea-level index points is generated from a coastal site on the east coast of Peninsular Malaysia. • Previously published, mangrove-based, sea-level index points from Peninsular Malaysia are re-calibrated. • The relative sea level in this far-field location felt below the present mean sea level during the late Holocene. • The Holocene RSL history, GIA and ESL in this location are discussed. [ABSTRACT FROM AUTHOR]