Rapid Exhumation of Earth's Youngest Exposed Granites Driven by Subduction of an Oceanic Arc

Exhumation of plutonic systems is driven by a range of mechanisms including isostatic, tectonic, and erosional processes. Variable rates of plutonic exhumation in active subduction systems may be driven by idiosyncrasies of regional geology or by first‐order tectonic features. We report new age, isotope, and low‐temperature thermochronology constraints of granitoids from the Hida Mountains of central Japan that constrain the highest rates and magnitude of plutonic rock exhumation within the Japan and one of the highest worldwide. This extreme exhumation is centered on the apex of a lithospheric scale anticlinorium associated with the subduction of the Izu‐Bonin oceanic arc. The spatial and temporal relationship between the exhumation of these Pleistocene plutons and the subducting/accreting Izu‐Bonin oceanic arc links the plate‐scale geodynamics and regional exhumation patterns. Identifying thermochronological anomalies within magmatic arcs provides an opportunity to identify ancient asperities previously subducted and responsible for rapid exhumation rates within ancient subduction systems. Plain Language Summary Plutonic rocks reach the surface through a variety of geological processes. Generally, this is driven by active tectonic and erosive forces. We provide high‐precision geochronological constraint on the youngest exposed subduction zone plutons found in the Hida Mountains of Japan that are 818.5 ± 9.6 thousand years old. Regionally, the Hida Mountains is identified as a thermochronological “hot spot” where the rocks in the region came to the surface very rapidly within the past ~300,000 years. The exhumation of these plutons was driven by the subduction of the Izu‐Bonin oceanic arc. Key Points Timing of crystallization and exhumation of the youngest exposed plutons is constrained with high precision analytical techniques One of the highest exhumation rates for plutonic rocks worldwide is reported Exhumation of Pleistocene granitoid plutons is driven by subducting Izu‐Bonin oceanic arc