Morphometric analysis of cirques in central Siberia's western Putorana Plateau: a proxy for palaeoclimate

A detailed morphometric analysis of 200 cirques across the western Putorana Plateau, central Siberia, was undertaken to investigate cirque development, reconstruct glaciers and infer palaeoclimatic conditions. Cirques are amphitheatre‐shaped landforms with mean length and widths of 936 and 1000 m, respectively, indicating a mature glacial landscape shaped by prolonged erosion. Cirques exhibit near‐circularity (mean ratio 1.05) and a width–height ratio (3.44), indicating their characteristics of wider‐than‐deep form, with significant erosion of headwalls. Strong positive correlations between length, width and height (L/W: 0.758; L/H: 0.610) suggest that these dimensions scale together. A dominant northwesterly aspect reflects climatic conditions under which the cirques formed. PalaeoIce 2.0 reconstructions indicate that cirque glaciers generated a total reconstructed ice volume of 10.6 km 3 . Reconstructed glaciers attained a median ice thickness of 55.9 m and a maximum of 260.6 m, whilst equilibrium‐line altitudes reconstructed using the AAR and AABR methods ranged from 593 to 1372 m a.s.l. with median values of 818–826 m a.s.l. Strong positive correlations between glacier thickness and cirque dimensions indicate that basin geometry exerted a control on ice accumulation. Using the reconstructed ELAs, a snowline depression was calculated relative to present‐day conditions. Estimated temperature depressions range from 5.0 to 5.7 °C under mean conditions, and up to 7.2 °C under the coldest scenarios. This corresponds to summer temperatures of 0.3 to −0.4 °C and annual temperatures of −14.7 to −15.4 °C. Estimated palaeoprecipitation values of 875–1036 mm a −1 suggest that sufficient moisture was needed to sustain cirque‐style glaciation. These findings provide the first quantitative reconstruction of cirque glaciers in the western Putorana Plateau and demonstrate that the region supported mountain glaciation during cold stages of the Late Pleistocene. This study provides new constraints on former glacier extent, equilibrium‐line altitudes and palaeoclimatic conditions, contributing to a broader understanding of mountain glaciations across Siberia.