Frost-weathering control on the rate of late Quaternary landscape evolution, western flank of the Taebaek Mountain Range, Korea: a case of passive margin landscape evolution

Abstract

Passive continental margins can show anomalously high topography and exhibit a discrete steep escarpment, divide, and gentle slope from the exterior to the interior of the margin. Compared with active (i.e. convergent and strike-slip) tectonic regions, the processes and rates of change of high-altitude landscapes driven by tectonics and/or climate in tectonically inactive (passive) continental margins are poorly understood. We used Be-10 catchment-wide denudation rates of fluvial sands (n = 29) collected in 17 catchments and 12 sub-catchments, as well as topographic analysis, to quantify the rate of landscape change along the western flank of the Taebaek Mountain Range (TMR). The denudation rates range from similar to 20 to similar to 70 mm/ka. These rates show no significant difference between upstream and downstream areas, implying that denudation is not (or is only negligibly) affected by deep-seated mass wasting processes and human impact. Be-10 denudation rates in the northern TMR are 1.6 times higher than in the south. In addition, the relationship between denudation rates and geomorphic parameter values also differs from north to south. These observed spatial differences in the rate of denudation and geomorphic response can be explained by intense frost weathering rather than lithological control. Our quantitative analysis of denudation rates and topography suggests that southwest-directed migration of the range's main divide occurs and that the range's western flank (low relief) is likely to be in a geomorphic state of quasi-equilibrium whereas the eastern flank (steep) still remains transient.