Identifying glacio–isostatic rebound processes using testate amoeba as palaeohydrological proxies; a case study from subarctic Québec, Canada

Abstract

Glacio–isostatic rebound is one of the most important landscape processes affecting the northern and northeastern coast of Canada and, therefore, reconstruction of postglacial rebound rates is critical for a better understanding of landscape evolution in this region. Yet, studies reconstructing coastal palaeogeography in Northern Canadaare constrained by the limitation of shell–based radiocarbon chronologies used in dating shoreline displacementand palaeo–sea levels. This study proposes an alternative methodology for the reconstruction and dating of palaeo–sea levels, which uses testate amoeba microfossils from coastal sediments as palaeoecological markers of coastal water table shifts linked to sea level change. Our results indicate that testate amoeba–inferred water table reconstruction is a good indicator of water table drawdown due to isostatic uplift on affected coastlines. Furthermore, radiocarbon dating of distinct plant macrofossils within the transitional marine/freshwater stratigraphy avoids the inherent reservoir effect issues associated with dating of marine shells.