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MODELLING HOLOCENE SEA-LEVEL OBSERVATIONS FROM THE CARIBBEAN AND SOUTH AMERICA

MODELLING HOLOCENE SEA-LEVEL OBSERVATIONS FROM THE CARIBBEAN AND SOUTH AMERICA. G.A. Milne 1 , A.J. Long 2 , S.E. Bassett 1. 1 Dept. of Geological Sciences, University of Durham, UK 2 Dept. of Geography, University of Durham, UK. Key Applications of Far-Field Holocene Sea-Level Observations.

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MODELLING HOLOCENE SEA-LEVEL OBSERVATIONS FROM THE CARIBBEAN AND SOUTH AMERICA

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  1. MODELLING HOLOCENE SEA-LEVEL OBSERVATIONS FROM THE CARIBBEAN AND SOUTH AMERICA G.A. Milne1, A.J. Long2, S.E. Bassett1 1 Dept. of Geological Sciences, University of Durham, UK 2 Dept. of Geography, University of Durham, UK

  2. Key Applications of Far-Field Holocene Sea-Level Observations ●Timing of major reduction in glacial melting. ●Volume and rate of glacial melt influx since the cessation of major melting. ●Relative contributions of the major ice reservoirs to the estimated melt signal? ● Magnitude and variation of viscosity structure with depth in the mantle.

  3. Sea-Level Model ●Based on theory published by Farrell and Clark (1976). ●Theory extended to include: (1) Time-dependent shorelines (Johnston 1993; Peltier 1994; Milne et al. 1999). (2) Glaciation-induced perturbations to Earth rotation (Han and Wahr 1989; Bills and James 1996; Milne and Mitrovica 1996; 1998). (3) The influence of marine-based ice sheets (Milne 1998; Peltier 1998). ●Earth model: spherically symmetric, self-gravitating, viscoelastic rheology. ●Ice model: based on ICE-3G (Tushingham and Peltier 1989); Laurentide component scaled to produce a good fit to Barbados sea-level curve (Bassett et al. 2003).

  4. hL=96 km UM=5x1020 Pa s LM=1022 Pa s

  5. Total Ice Ocean

  6. Total Rotation Rotation

  7. hL=96 km UM=5x1020 Pa s LM=1022 Pa s

  8. hL=96 km UM=5x1020 Pa s LM=1022 Pa s

  9. hL:71 – 120 km UM:(1 – 10) x 1020 Pa s LM:(1 – 50) x 1022 Pa s

  10. SUMMARY • ●Data suggest that rate of melt water flux into the oceans dropped significantly around 7 kyr BP. • ●Removing the GIA component of the signal suggests that perhaps a small amount of net melting (~1 – 2 m) could have occurred between 7 and 5 kyr with very little or no melting since about 5 kyr BP. • ●The magnitude of the GIA correction is sensitive to the adopted viscosity profile and so the “corrected” data should be interpreted with caution.

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