Geomorphic Features of the Eastern Pamirs, with a Focus on the Occurrence of Intermontane Basins

Abstract

The geomorphic landscape of the Pamirs differs distinctly between the western and eastern areas. The Western Pamirs (west of ~73°E) are characterised by a combination of predominantly west–east-trending mountain ranges with altitudes of 5000–7000 m and deep, narrow valleys. In contrast, the Eastern Pamirs (east of ~73°E) are generally distinguished as broad valleys and basins bordered by more subdued mountain ranges with altitudes of 5000–6000 m. Twelve intermontane basins—Khargush Pamir (Lake Karakul Basin), the basin at the confluence of the Kokuibel and Zartosh Rivers, Muji Basin, the upper reaches of the Gez River, Karasu Valley, Taghdumbash Pamir (Tashkurgan Valley), Rangkul Pamir, Sarez Pamir, Aksu Valley, Alichur Pamir, Great Pamir, and Little Pamir—are identified in the Eastern Pamirs. I deduced from previous studies and observations of landforms using Google Earth that the occurrence of such basins is associated with regional tectonics, downstream damming, and glaciation. Khargush Pamir, the basin at the confluence of the Kokuibel and Zartosh Rivers, Muji Basin, the upper reaches of the Gez River, Karasu Valley, and Taghdumbash Pamir are extensional basins bounded by active normal faults, and the Rangkul Pamir likely originated from a Cenozoic tectonic basin. Sarez Pamir, Aksu Valley, Alichur Pamir, Great Pamir, and Little Pamir have been protected from fluvial incision because of downstream-damming-related upstream aggradation. Alichur Pamir, Great Pamir, and Little Pamir were primarily formed by extensive glacial denudation.