Integrating cirque morphometrics and numerical modelling reconstructions in Putorana, Central Siberia

A detailed morphometric and modelling-based analysis was conducted on 197 palaeocirques across the western Putorana Plateau, Central Siberia, to refine reconstructions of mountain glacier extent and associated palaeoclimatic conditions during the last major phase of glaciation. Previous work in the region quantified cirque geometry and inferred palaeo-equilibrium line altitudes from cirque floor elevations. Here, these geomorphological constraints are integrated with physically based glacier reconstructions using the PalaeoIce 2.0 model to simulate ice thickness, surface geometry, and glacier extent for individual cirques.

The cirques display mean widths of approximately 1000 m and mean lengths of 936 m, forming near-circular, amphitheatre-like landforms indicative of sustained glacial erosion. Cirque heights range from 111 to 591 m, reflecting both variability in erosional intensity and topographic controls. Strong positive correlations between length, width, and height (L×W: 0.758; L×H: 0.610) indicate proportional scaling of cirque dimensions. Mean cirque slopes are 23.5°, with steep headwalls reaching up to 80°, while more than half of cirque areas are characterised by gentler slopes associated with overdeepened floors, where tarns are frequently present.

Cirque floor altitudes range from 447 to 1568 m, providing first-order constraints on former glacier geometry. PalaeoIce 2.0 reconstructions indicate a mean palaeo-equilibrium line altitude of approximately 658 m, corresponding to a depression of ~1042 m relative to present conditions. Modelled glacier geometries are consistent with extensive, topographically confined mountain glaciers developed within individual cirques during the Last Glacial Maximum. Associated palaeoclimate estimates suggest mean summer air temperatures of approximately −1.5 °C and annual precipitation of ~634 mm to sustain such glaciation.

These results demonstrate the value of combining cirque morphometrics with numerical ice-flow modelling to refine palaeoglacier reconstructions in high-latitude mountain regions. The PalaeoIce 2.0 simulations provide an independent, physically based framework for evaluating cirque-derived palaeoclimate inferences and for improving understanding of mountain glacier behaviour along the margins of larger ice-sheet systems.