Origin and evolution of the Paleo‐Kuril arc inferred from detrital zircon U–Pb chronology in eastern Hokkaido, NE Asia

Abstract

The Nemuro and Saroma Groups and Yusenkyo Formation occur in eastern Hokkaido and are considered to be forearc or intra‐arc basin sediments of the Paleo‐Kuril arc (PKA) deposited during the Late Cretaceous to middle Eocene. To further clarify the origin of the PKA, we examined the U–Pb ages of detrital zircons within these sandstones and acidic tuff beds; based on our results, we drew the following conclusions. (1) The PKA originated from an oceanic island arc on the oceanic Izanagi Plate around 85 Ma, to which the Nikoro Group greenstone complex was accreted between 81–80 Ma; the Lowest Unit of the Saroma Group covered the surface of the Nikoro accretional greenstone complex. (2) The PKA then first collided with NE Asia around the beginning of the deposition of the Hamanaka Formation (~70 Ma) and transitioned to a continental arc adjacent to NE Asia. This collision generated giant slump beds during deposition of the Akkeshi Formation. During deposition of the Kiritappu Formation, the entire Nemuro Peninsula was uplifted, supplying large volumes of clastic sediments. (3) Although we do not have data directly bearing on why the North American Plate was established in the edge of NE Asia, we speculate that it separated from the Eurasian continent around ~70 Ma when NE Asia first collided with the PKA. Subsequently, the PKA has behaved as part of the North American Plate. The Paleo‐Japan arc (or East Sikhote–Alin arc) and the PKA became joined via the Hidaka Belt. Around 40 Ma, during the deposition of coarse conglomerate beds of the Urahoro Group, the PKA was uplifted and bent clockwise due to a second collision with NE Asia. (4) The modern Kuril arc was established around 36 Ma (late Eocene–early Oligocene), and the Kuril backarc basin opened into the present tectonic setting in the late Oligocene–early Miocene.

Cretaceous to early Paleogene sediment provenance transition from continental to magmatic arc systems in the Northwestern Pacific Region

“…The sample of the Lowest Saroma Group measured by Nanayama et al 7 indicated intermediate Bayesian Population Correlations values (0.06–0.58) with Type 1 distributions (Fig. 3 ).…”

“…While in the Tokoro Belt, radiometric and biostratigraphic ages were analyzed, such as: Dinoflagellate 30 , Radiolarians 31 , 32 , and K–Ar dating 33 . Detrital zircon U–Pb analysis from Harisma et al 6 ( a – g , k , l , o ); Nanayama et al 7 ( h , i , m , n , u ). n number of zircon grain analyses, Fm formation, Mbr member.…”

“…3 ). In addition to the samples of this study, data from previous literature 6 , 7 were included in this analysis. The samples from the Lower and Middle Saroma Group (ST18LSR5 and ST17MSR1), the Hamanaka (ST3HM4 and KS-HMt-01), the Akkeshi (ST1AK4, ST2AK3, and KS-AKb-01), and the Kiritappu (ST15KR5) Formations of the Nemuro Group, and the Kamibaro (ST22KMB5) and the Yasukuni (ST20YSK1) Units of the Yubetsu Group were classified into Type 1.…”

“…The recent geochronological analysis of Harisma et al 6 in the Late Cretaceous–Paleogene Nemuro Belt implied that the sediment of the Paleo-Kuril Arc was not only supplied with sediments from rocks of its local igneous origin but also from the Precambrian continental crust, suggesting that the Paleo-Kuril Arc originated along the southern end of the Okhotsk Block as a continental arc system during the Late Cretaceous. In contrast, another geochronological study suggested that the Paleo-Kuril Arc could have developed as an immature oceanic island arc system in the Late Cretaceous 7 because it did not detect detrital zircon grains before 85 Ma in the basal successions of the Tokoro Belt, which is part of the Paleo-Kuril Arc system 7 . The geochemical analysis of the igneous rocks in the Nemuro Belt also suggested that the Paleo-Kuril Arc may have developed as an immature magmatic arc system 8 .…”

“…Aiming to conclude the discussions on the origin of the Paleo-Kuril Arc, we report the U–Pb age distributions of the detrital zircon grains newly obtained from sandstone samples of the Late Cretaceous Saroma and the Late Cretaceous–Paleogene Yubetsu Groups in the Tokoro Belt distributed in eastern Hokkaido. We then conducted statistical analyses with integrated datasets using existing detrital zircon data from the Nemuro and Tokoro Belts 6 , 7 , 10 to provide new insights into the link between the two tectonic belts and the evolution of the Paleo-Kuril Arc.…”