Isolation basin records of late Quaternary sea-level change, central mainland British Columbia, Canada

Isolation basin records from the Seymour-Belize Inlet Complex, a remote area of central mainland British Columbia, Canada are used to constrain post-glacial sea-level changes and provide a preliminary basis for testing geophysical model predictions of relative sea-level (RSL) change. Sedimentological and diatom data from three low-lying (<4 m elevation) basins record falling RSLs in late-glacial times and isolation from the sea by similar to 11,800-11,200 C-14 BP. A subsequent RSL rise during the early Holocene (similar to 8000 C-14 BP) breached the 2.13 m sill of the lowest basin (Woods Lake), but the two more elevated basins (sill elevations of similar to 3.6 m) remained isolated. At similar to 2400 C-14 BP, RSL stood at 1.49 +/- 034 m above present MTL. Falling RSLs in the late Holocene led to the final emergence of the Woods Lake basin by 1604 36 14C BP. Model predictions generated using the ICE-5G model partnered with a small number of different Earth viscosity models generally show poor agreement with the observational data, indicating that the ice model and/or Earth models considered can be improved upon. The best data-model fits were achieved with relatively low values of upper mantle viscosity (5 x 10(19) Pa s), which is consistent with previous modelling results from the region. The RSL data align more closely with observational records from the southeast of the region (eastern Vancouver Island, central Strait of Georgia), than the immediate north (Bella Bella-Bella Coola and Prince Rupert-Kitimat) and areas to the north-west (Queen Charlotte Sound, Hecate Strait), underlining the complexity of the regional response to glacio-isostatic recovery. (C) 2013 Elsevier Ltd and INQUA. All rights reserved.