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Holocene sea-level rise, monsoonal discharge and human activity have been the main drivers for the evolutionary history of Asian deltas. In theory, when sea level ceased to rise in around 7000 cal. a BP, deltas should have started to prograde seawards. However, previous studies revealed that the progradation of modern deltas was initially very slow, and more importantly, sediment accumulation within central deltaic basins was exceptionally low between 7000 and 4000 cal. a BP. In order to investigate the main reasons for such slow progradation and low sedimentation during the middle Holocene, this study reconstructed the sedimentary history of the head area of the Pearl River delta. The results show marine transgression from 9500 to 7500 cal. a BP, followed by marine regression starting from 7500 to 4000 cal. a BP, in response to sea-level change. During the latter period, sedimentation was concentrated in the head area. The amount of sediment entering the central basin was significantly reduced. This limited amount of sediment was spread thinly across the wide deltaic basin. A portion of it could have been transported out into the South China Sea by the strong tidal currents, resulting in an exceptionally low sedimentation in the central basin. However, in locations adjacent to former/present islands, locally supplied sediment helped sedimentation to continue from 7500 to 4000 cal. a BP. By about 4000 cal. a BP, the deltaic shoreline advanced into the central basin. This period saw an increase of human activity that caused soil erosion and sediment supply, leading to a marked increase in sedimentation rate. Active land reclamations also helped the acceleration of shoreline advance. This sedimentary evolution model in the Pearl River delta mirrors those of other deltas in the monsoonal Asia. • New sedimentary core records were reported for the head area of the PRD. • A three-stage history of the landform evolution in the head area was reconstructed. • Holocene sediment accumulation models were identified for the head area, central wide deltaic basin and peri-island area. • Reasons for the mid-Holocene low sedimentation in the PRD were discussed along with other Asian deltas. [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]