Support Data for Deciphering spatio-temporal variations in Holocene relative sea level in the South China Sea: from local reconstructions to a regional database
Chapter Two investigates the application of microfossils and δ13C and C/N geochemistry to develop high-resolution late Holocene RSL records from sediments in Deep Bay, located on the eastern side of the PRD. This chapter characterises the contemporary distribution of these proxies across three transects encompassing subtidal, intertidal (mudflat and mangrove), and upland environments. Partitioning Around Medoids (PAM) analysis is employed to characterise distinct biozones based on microfossil assemblages, while CCA examines the relationships between contemporary diatom and foraminiferal communities and environmental variables. Bayesian transfer functions (BTFs) are developed using modern foraminiferal and diatom assemblages, incorporating priors informed by δ13C and C/N geochemistry. These BTFs are applied to a sediment core obtained from a contemporary mangrove setting in Mai Po, Deep Bay, to evaluate their efficacy. The reconstructions are subsequently validated against local tide gauge data to assess the relative effectiveness of foraminiferal and diatom-based proxies in reconstructing RSL changes. This chapter has been submitted to Marine Geology.
Chapter Three establishes the indicative meaning of S. cuccullata examining its contemporary vertical distribution along rocky coasts in Hong Kong, including periodic inundated thin S. cuccullata beds in elevated tidal pools. The elevation of the ancient oyster bed is resurveyed, and its morphology and depositional context are documented. Petrographic analysis and X-ray diffraction are used to evaluate the lithology and mineralogy of the ancient oyster bed, and therefore classify the reef and reconstruct the environment where it formed. Additionally, two new radiocarbon dates are obtained from samples collected at different elevations within the ancient bed to reconstruct mid-Holocene RSL in Hong Kong, constraining the timing and magnitude of the highstand in the region. This chapter has been prepared to be submitted to Palaeogeography, Palaeoclimatology, Palaeoecology.
Chapter Four develops a quality-controlled Holocene RSL database for the SCS coast, incorporating SLIPs and limiting points derived from sedimentary, geomorphic, coral, fixed biological, and archaeological indicators spanning 14 ka to the present. Uncertainties associated with tidal range changes over the Holocene are addressed using a paleotidal model. Spatio-temporal fields of RSL change are reconstructed, with RSL and rates of RSL change estimated by applying SPTEHM to the database. Sensitivity tests are performed to examine the effects of global and Antarctic ice sheet deglaciation timing and variations in 3D Earth structure, including lateral heterogeneity, on GIA model predictions. The results are used to interpret regional and local processes driving spatio-temporal variability in RSL change. This chapter has been prepared to be submitted to Quaternary Science Reviews.
