Late Palaeogene emplacement and late Neogene–Quaternary exhumation of the Kuril island-arc root (Kunashir island) constrained by multi-method thermochronometry

Reconstruction of Subduction and Back‐Arc Spreading in the NW Pacific and Aleutian Basin: Clues to Causes of Cretaceous and Eocene Plate Reorganizations

“…The active part of the Kuril arc is thought to have developed in the Late Oligocene to Early Miocene (Avdeiko et al, ; Martynov et al, ). Recently, De Grave et al () obtained a U‐Pb zircon age of 31.3 ± 1.1 Ma from a granodiorite intrusion derived from the basement of Kunashir Island, indicating that the Kuril arc started activity in or prior to the Early Oligocene. Dredged rocks of the submarine Vityaz Ridge similar to those of the onshore Nemuro belt (Lelikov & Emelyanova, ) imply that the modern Kuril arc was built upon crust of the East Sakhalin‐Nemuro paleo‐arc.…”

“…Tectonics the Pacific plate below the Kuril Trench, extends from eastern Hokkaido to the Kamchatka peninsula ( Figures 1 and 2), with the oldest magmatic rocks dated as Early Oligocene (De Grave et al, 2016). Behind the Kuril arc is the wedge-shaped oceanic Kuril Basin ( Figure 2).…”

“…Structurally above the units interpreted to belong to Eurasia, or on Hokkaido separated from Eurasia by a strike‐slip fault, are the Late Cretaceous to early Paleogene East Sakhalin‐Nemuro island‐arc units found on east Hokkaido and east Sakhalin (e.g., Nokleberg et al, , ; Ueda, ; Zharov, ; Figures ). The Kuril volcanic arc, associated with the subduction of the Pacific plate below the Kuril Trench, extends from eastern Hokkaido to the Kamchatka peninsula (Figures and ), with the oldest magmatic rocks dated as Early Oligocene (De Grave et al, ). Behind the Kuril arc is the wedge‐shaped oceanic Kuril Basin (Figure ).…”

“…We model up to 800 km of N‐S extension along the transform boundary with Sakhalin (Figure ), following Schellart et al (). This requires that the Kuril Trench must have existed and rolled back since at least 40 Ma, and subduction thus starting prior to the oldest dated island‐arc rocks from the Kuril volcanic arc that have an Early Oligocene age (De Grave et al, ). Our reconstructions suggest that up to 3,000 km of subduction occurred along the Kuril‐Kamchatka Trench, consistent with the long slab in the upper and top of the lower mantle, whereby the flat portion of the Kuril‐Kamchatka slab (Figure ) is similar in length to the amount of extension modeled in the Sea of Okhotsk and Kuril Basin.…”

Low‐temperature thermochronological database of bedrock in the Japanese Islands

“…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. The He data of Sueoka, Tagami, et al (), Ahadi et al (), and the unpublished data in the Tono area were not included in the compilation because some were still being measured.…”