Eustatic change modulates exhumation in the Japanese Alps

The exhumation of bedrock is controlled by the interplay between tectonics, surface pro-cesses, and climate. The highest exhumation rates of centimeters per year are recorded in zones of highly active tectonic convergence such as the Southern Alps of New Zealand or the Himalayan syntaxes, where high rock uplift rates combine with very active surface processes. Using a combination of different thermochronometric systems including trapped-charge ther-mochronometry, we show that such rates also occur in the Hida Mountain Range, Japanese Alps. Our results imply that centimeter per year rates of exhumation are more common than previously thought. Our thermochronometry data allow the development of time series of exhumation rate changes at the time scale of glacial-interglacial cycles, which show a four-fold increase in baseline rates to rates of -10 mm/yr within the past -65 k.y. This increase in exhumation rate is likely explained by knickpoint propagation due to a combination of very high precipitation rates, climatic change, sea-level fall, range-front faulting, and moderate rock uplift. Our data resolve centimeter-scale sub-Quaternary exhumation rate changes, which show that in regions with horizontal convergence, coupling between climate, surface processes, and tectonics can exert a significant and rapid effect on rates of exhumation.

Automated summary

The exhumation of bedrock is controlled by the interplay of tectonics, surface processes, and climate. This study shows that high exhumation rates are not only found in highly active tectonic convergence zones, but also in the Hida Mountain Range, Japanese Alps. The study also reveals that exhumation rates can change significantly within glacial-interglacial cycles, possibly due to a combination of factors.