Denudation history of the Akaishi Range, central Japan, and its tectonic implications; Constraints from low-temperature thermochronology

Sueoka, Shigeru   ; Kohn, B.*; Ikeda, Yasutaka*; Kano, Kenichi*; Tsutsumi, Hiroyuki*; Tagami, Takahiro*; Hasebe, Noriko*; Tamura, Akihiro*; Arai, Shoji*

Thermochronometric methods are used to identify the denudation history of the Akaishi Range, which has been uplifted since the late Pliocene. ZHe grain ages range 21.5-3.0 Ma and systematically younger to the east, implying a westerly tilting uplift of the Akaishi Range. We estimated denudation rates at 1.2-2.2 mm/yr or more in the Akaishi Range. These high denudation rates imply the topography of the Akaishi Range reflects post-uplift factors, e.g., spatial distribution of bedrock uplift rates and various denudation processes, rather than inherited geometry from the pre-uplift topography. Considering younger AFT ages previously reported in the southern part of the Akaishi Range, the Akaishi Range is considered to have had at least two uplifting stages, i.e., uplifting of the northern part since the late Pliocene and uplifting of the southern part since 1 Ma, probably attributable to reverse faulting of ISTL and collision of the Izu block to the south Fossa Magna area, respectively.