Empirical estimation of isostatic uplift using the lake-tilting method at lake Fegen and lake Säven, southwestern Sweden

Abstract

A nonuniform glacio-isostatic uplift results in differential uplift for different parts of a lake. If the lake outlet is situated in the area with the greatest rate of uplift, then the lake will be continuously transgressed. Ancient lake levels can be estimated by dating transgressed peat at different depths in such a lake. Two lakes in southwestern Sweden have been investigated by this method and the course of glacio-isostatic uplift has been determined empirically. The uplift can be expressed by an exponential function through the following formula

$$U = - \frac{{\upsilon _0 }}{{2.25 \times 10^{ - 4} }} + \frac{{\upsilon _0 }}{{2.25 \times 10^{ - 4} }}e^{2.25 \times 10^{ - 4} xt} $$

where U is land uplift inm, v₀ is recent absolute uplift rate in m/year, andt is time in years BP. The recent absolute uplift rate is found to be somewhat faster than the relative rate established by earlier repeated precision levelings. This may be due to the present eustatic sea level rise on the order of 1.0 mm/year or possibly to irregularities in the glacio-isostatic uplift. By combining shore-level data with uplift data, some alternative eustatic curves have been calculated.