Quaternary palaeogeography as revealed by cirque morphology in the Qimantag Mountains, northern Tibetan Plateau

Cirque morphology provides insights into past glaciation and palaeoclimate. The Qimantag Mountains preserve abundant glacial landforms but remain poorly investigated compared with other parts of High Mountain Asia. This study aims to quantify the morphology of cirques and contemporary glaciers in the Qimantag Mountains and to use cirque morphometry to reveal the glacial and palaeoenvironmental conditions since the Quaternary in the region. We mapped 90 cirques (33 ice-free and 57 ice-filled) and quantified their morphometry using the extended Automated Cirque Metric Extraction (ACME2) toolbox, along with the morphometric characteristics of 214 contemporary glaciers. The results show that cirques in the Qimantag Mountains are generally larger than those in the eastern Kunlun Mountains, indicating longer-lasting occupation by cirque glaciers. This contrast may be attributed to differences in moisture supply. Cirques in the Qimantag Mountains show a dominant elongation pattern, implying stronger headwall erosion than lateral and subglacial erosion. A pronounced NNE orientation of cirques was identified, consistent with the influence of the "morning-afternoon effect". Contemporary glaciers exhibit a more northerly vector mean than both ice-filled and total cirques, with higher vector strength values, indicating stronger directional concentration under the present climate. Cirque morphometry varies with aspect: cirque floor altitude and mean altitude are higher on south-facing slopes, highlighting the influence of solar radiation on cirque development. East-facing cirques are longer than west-facing cirques, suggesting stronger westerlies during their formation than today. The obtained cirque morphological parameters provide valuable evidence for understanding the Quaternary palaeogeographic evolution of the northern Tibetan Plateau.