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Geodynamics Series

 

Keywords

  • Glacial isostasy
  • Sea level
  • Earth-Crust
  • Geodynamics

Index Terms

  • 1236 Geodesy and Gravity: Rheology of the lithosphere and mantle
  • 4556 Oceanography: Physical: Sea level variations
  • 8162 Tectonophysics: Rheology—mantle

Article

GEODYNAMICS SERIES, VOL. 29, PP. 33-50, 2002

Sea level change from mid Holocene to Recent time: An Australian example with global implications

K. Lambeck

Observed relative sea-level change reflects changes in ocean volume, glaciol-hydro-isostasy, vertical tectonics and redistribution of water within ocean basins by climatological and oceanographic factors. Together these factors produce a complex spatial and temporal sea-level signal. For the tectonically stable Australian margin, geological evidence indicates that sea-levels at 7000–6000 years ago were between 0 and 3 m above present level, due primarily to glacio-hydro-isostatic effects of the last deglaciation. The spatial variability of this signal determines the mantle response to the surface loading and leads to an effective lithospheric thickness of 75–90 km and an effective upper mantle viscosity of (1.5–2.5)×1020 Pa s. Compared with results for other regions this is indicative of regional variation in upper-mantle response. Also, ocean volumes continued to increase after 7000 years ago by enough to raise global mean sea level by about 3 m. Much of this increase occurred between 7000 and 3000 years ago. Because of the spatial variability in mantle response, isostatic corrections to tide-gauge records of recent change should be based on regional model-parameters rather than on global parameters. The two longest records from the Australian margin give an isostatically corrected rate of regional sea-level rise of 1.40±0.25 mm/year. Comparisons of this rate with rates from other regions indicates that the spatial variability in secular sea-level is likely to be significant, with estimates of regional rates ranging from about 1 mm/year to 2 mm/year. These rates of secular change cannot have persisted further back in time than a few hundred years without becoming detectable in high-resolution geological and archaeological indicators of sea-level change.

Citation: Lambeck, K. (2002), Sea level change from mid Holocene to Recent time: An Australian example with global implications, in Ice Sheets, Sea Level and the Dynamic Earth, Geodyn. Ser., vol. 29, edited by J. X. Mitrovica and B. L. A. Vermeersen, pp. 33–50, AGU, Washington, D. C., doi:10.1029/GD029p0033.

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