Uplift and denudation history of the Akaishi Range, a thrust block formed by arc‐arc collision in central Japan: Insights from low‐temperature thermochronometry and thermokinematic modeling

Abstract

Fission track (FT), (U‐Th)/He (He), and U‐Pb data were used to identify the denudation history of the Akaishi Range, central Japan. The northern Akaishi Range is bounded on the east by the Itoigawa‐Shizuoka Tectonic Line Fault Zone (ISTL‐FZ). The thermochronometric ages progressively decrease with the decreasing distance to the ISTL‐FZ. Thermokinematic calculations suggest that the age pattern observed can be explained by 5–7.5 mm/yr reverse slip on the ISTL‐FZ that dips 34–45° west and soles onto detachment at 20–22.5 km depth. By assuming the same geometry and slip rate of the fault, the bedrock uplift rates and denudation rates are estimated at ~4 mm/yr. Thus, the uplift and denudation style of the northern Akaishi Range is well explained as a simple tilted thrust block that has been exhumed along the listric ISTL‐FZ. On the other hand, considering both the difference in apatite FT age and the active fault distribution, the southern Akaishi Range might be different in uplift origin and timing, although the difference in apatite FT ages between them may be attributable to the chlorine content variation in apatite. The inferred total denudation is larger than several kilometers and likely exceeds 10 km since the beginning of the northern Akaishi Range uplift, suggesting that the low‐relief surfaces on the ridges and the relatively constant elevations of the summits reflect postuplift denudation rather than preexisting low‐relief landforms.

Low‐temperature thermochronological database of bedrock in the Japanese Islands

“…The number of He data in the compilation is low, which would still be the case if the unpublished data were included, which were excluded from the compilation (Figure ). the He ages were only reported for the Tohoku region (Sueoka, Tagami, & Kohn, ; Sueoka, Tagami, Kohn, & Fukuda, ), Hida Range (Ahadi et al, ), Kiso Range (Sueoka et al, ), Akaishi Range (Sueoka et al, ; Sueoka et al, ), Tanzawa Mountains (Yamada & Tagami, ), Tono area (unpublished data), Taki area in the Kii Peninsula (Yamada et al, ), and Awaji Island (Ito, ). He ages were also obtained in the Kunashiri Island (De Grave et al, ), but the border of this region is disputed by Russia and Japan.…”

“…In this region, high mountains were formed in the Late Pliocene and Quaternary, which was mainly related to active faulting. Therefore, a substantial number of ages was obtained for reconstructing the uplift/denudation history of these mountains (e.g., Ito & Tanaka, 1999;Sueoka et al, 2012;Sueoka, Ikeda, et al, 2017;Yamada & Tagami, 2008). Many data were also reported for the area along the Pacific coast of the outer zone of the Southwest Japan, where the exhumation and evolution histories of the accretionary complexes have mainly been investigated (e.g., Hasebe et al, 1993;Hasebe & Tagami, 2001…”

Estimation of emplacement depth for the Miocene Kaikomagatake granitoid pluton: constraints on crustal denudation history of the Izu collision zone

“…The SHRIMP U-Pb zircon age shows older age at the margin of the pluton and younger age in the center of the pluton indicative of crystallization start form the margin. Recently, a detailed thermochronological study by Sueoka et al (2017) reported zircon U-Pb age of 13.8-12.4 Ma, zircon fission-track age of 10.0-5.6 Ma, zircon (U-Th)/He age of 8.8-3.4 Ma and apatite fission-track age of 8.2-3.1 Ma.…”

“…1b). Recently, precise low-temperature thermochronological study with thermokinematic modeling has been performed on the Kaikomagatake pluton (Sueoka et al, 2017), illustrating the denudation history of the Akaishi Range where the pluton is distributed. Therefore, estimation of emplacement depth of the Kaikomagatake pluton will provide petrological constraints on its denudation history, which in turn will be an important information on revealing tectonic evolution of the Izu collision zone.…”

“…Therefore, estimation of emplacement depth of the Kaikomagatake pluton will provide petrological constraints on its denudation history, which in turn will be an important information on revealing tectonic evolution of the Izu collision zone. However, emplacement depth of the Kaikomagatake pluton has not yet been investigated although numerous geological, petrologic, geochronological and geochemical studies have been performed on this pluton (Otsuka, 1940;Fujimoto et al, 1965;Shibata and Kobayashi, 1965;Kawano and Ueda, 1966;Yamada et al, 1983, Sato et al, 1989Ito et al, 1989;Shimamoto et al, 1991;Tsunoda et al, 1992;Tani, 2011;Saito et al, 2012;Sueoka et al, 2017).…”