Holocene glacial rebound and sea-level change in NW Europe

Abstract

S U M M A R Y Observations of Late Pleistocene and Holocene sea-level change relative to the crust exhibit very considerable variations across NW Europe in consequence of the response of the Earth's crust to the deglaciation of Fennoscandia and of the water added to the oceans from the melting of all Late Pleistocene ice sheets. Inversion of sea-level observations from a site near the centre of the Fennoscandian ice sheet and from three sites located beyond the margin of the ice sheet at the time of maximum glaciation yield a range of plausible models for the Earth's response and for the ice models. Further constraints on this range of models is placed by a comparison of observed sea-levels with predicted values at other sites near the former ice sheet margins. The resulting mantle parameters are: upper mantle viscosity (3-5) X 10'' Pa s; lower mantle viscosity (2-7) X loz1 Pa s; lithospheric thickness 100-150 km. These values represent effective parameters that describe the response of the Earth to surface loading of short to intermediate wavelengths on a time-scale of 104yr. The lower mantle viscosity is poorly constrained but the marked increase from upper to lower mantle is a characteristic of all plausible solutions. The inversion places a constraint on the total volume of ice in the Fennoscandian ice sheet such that the equivalent sea-level rise from this contribution is about 13-14 m. A less well-determined constraint of about 10 m equivalent sea-level rise is suggested for the Barents-Kara ice sheet. The inversion also indicates that a small amount of melt-water, from ice sheets far away from Europe, continued to be added into the oceans during Late Holocene time so as to raise the equivalent sea-level by about 3 m during the past 6000 yr, consistent with similar inversions of data from sites in the Australian and Pacific regions.

Hirnantian glacial and deglacial record in SW Djado Basin (NE Niger).

“…Faults trending N60°E, graben and clastic dyke characteristics, such as late Ordovician to pre-Silurian hydroplastic slickensides, reveal an interstadial and deglacial N330°E extensional event. This deformation is likely to reflect largescale doming resulting from lithosphere stretching further to ice-sheet melting, as evidenced by studies on glacio-isostatic observations coupled with rheological models [39,40]. Most studies evidenced that post-glacial rebound is proportional to the former ice thickness, and that related faults are oriented perpendicular to the maximal gradient in ice thickness [41].…”

A fully coupled 3-D ice-sheet–sea-level model: algorithm and applications

“…In particular, a long-term sea-level fall is observed in the proximity of the former LGM ice sheets (Lambeck et al, 1990). Moving slightly away from the formerly glaciated areas, the sea-level trend first switches towards a steep rise (Engelhart et al, 2011), reaching a midHolocene high stand (Basset et al, 2005) and then smoothly changes towards a eustatic-like sea-level fall that is observed at the far-field sites like Barbados and Tahiti (Fairbanks, 1989;Peltier and Fairbanks, 2006;Bard et al, 1996Bard et al, , 2010Deschamps et al, 2012).…”

Rates of Holocene isostatic uplift and relative sea‐level lowering of the Baltic in SW Finland based on studies of isolation contacts

“…Even though it is known that melting of the ice sheets generated a substantial rise in global ocean level until 6000-5000 BP (Lambeck et al 1990;Pirazzoli 1991), this component is extremely dif cult to determine accurately, because of deglacial geoidal changes (Fjeldskaar 1989(Fjeldskaar , 1994 and global crustal deformations after the end of the last cold stage (Pirazzoli 1991). Removing the in uence of eustatic rise would steepen the upper parts of the Ta-Pe and Ol-Py emergence curves, which must be taken into account when estimating the magnitude of crustal deformation in these areas during the past 8000 14 C years.…”