The lowermost last-glacial equilibrium line altitude in the Taiwanese Central Mountain Range and its implications for the palaeoclimate and the tropospheric moisture transport in East Asia

Abstract

The high mountains of Taiwan provide a unique location for Quaternary palaeoclimate research in East Asia and the north-western Pacific. This study applies geomorphological field mapping and rock surface exposure dating with paired (10Be/26Al) in situ-produced terrestrial cosmogenic nuclides to identify and date glacial landforms and boulders in a relatively low-elevated (<3300 m) section of the Taiwanese Central Mountain Range, the southern Nenggao Shan. We propose two major glacial phases during the last glacial cycle: 1) During the Marine Isotope Stage 3 to the early Marine Isotope Stage 2, a small plateau glacier covered the main crest with a glacier equilibrium line altitude at 2800 m. This is the lowest ever reported equilibrium line altitude in Taiwan. The ice retreated during or just before the global Last Glacial Maximum. This is consistent with scenarios from other East Asian mountain ranges. 2) During the late glacial until the early Holocene, six cirque glaciers formed exclusively in east-facing topographically favorable downwind positions. Their cirque floor elevations indicate an orographic equilibrium line altitude between 2700 m and 2800 m. These cirque positions confirm the dominant influence of the mid-latitude westerlies above the shallow winter monsoon on the high-altitude precipitation regime in East Asia.