Rates of erosion in the Japanese Alps during the Quaternary – Insights from trapped charge thermochronometry

The Japanese Alps uplifted throughout the Quaternary and reach elevations of up to 3,000 m today. However, understanding the interaction between rates of Earth surface processes, tectonics and climate is challenging, partly due to the difficulties of measuring changes in the rates of Earth surface processes at the timescale of glacial-interglacial cycles. In particular, the youth of the Japanese Alps has made measurement of their exhumation histories complicated. To help resolve this issue, we investigate the potential of ultra-low temperature thermochronometers based on the luminescence and electron spin resonance (ESR) of feldspar and quartz minerals, respectively. We focus on the Tateyama region in the Hida range, which was glaciated during the late Quaternary period. In total, eight samples were analyzed by luminescence and ESR thermochronometry. While most luminescence signals have already reached their upper dating limit, ESR signals do constrain exhumation rates.We measured the ESR dose response and thermal decay properties of all samples, specifically targeting the Al and Ti centres. In general, thermal stability is higher for the Ti centre than the Al centre, resulting in ESR ages of between 0.5-0.9 Ma, although the natural intensity of the Ti centre is close to or above the upper dating limit. In contrast, the Al signal still grows with time and is suitable for determining finite exhumation rates. Initial inversions reveal rock cooling rates on the order of 80 °C/Ma, which can be inverted to preliminarily rates of rock exhumation of