3:45 PM - 4:00 PM
[SGL23-02] Origin and the Paleo-Kuril arc and reconsideration of NE Asian tectonics
Keywords:Paleo-Kuril arc, NE Asia, Late Cretaceous
The Nemuro and Saroma Groups occur in eastern Hokkaido and are considered to be forearc basin sediments of the Paleo-Kuril arc (PKA) deposited during the Late Cretaceous to middle Eocene (Nanayama et al., 1993, 2022). To further clarify the origin of the PKA, we reviewed existing research results and drew the following conclusions.
(1) The PKA originated from an oceanic island arc on the oceanic Izanagi Plate around 85 Ma, to which the greenstone complex (Nikoro Group) 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 area 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 (Nanayama et al., 2021). It is possible that the Izanagi–Pacific Ridge collided with NE Asia during this period (Yamasaki et al., 2021).
(4) Around 40 Ma, during the deposition of coarse conglomerate beds of the Urahoro Group (Katagiri et al., 2019), the PKA was uplifted and bent clockwise due to a second collision with NE Asia.
(5) 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 (Nanayama et al., 2021, 2022).
References
Katagiri, T. et al., 2019, Collisional bending of the western Paleo-Kuril Arc deduced from paleomagnetic analysis and age determination. Island Arc, 2019, e12329.
Nanayama, F. et al., 1993, Sedimentary petrology and paleotectonic analysis of the arc-arc junction: the Paleocene Nakanogawa Group in the Hidaka Belt, central Hoikkaido, Japan. Palaeogeography, Palaeoclinatology, Palaeoecology, 105, 53-69.
Nanayama, F. et al., 2021, The emplacement of in situ greenstones in the northern Hidaka belt: the tectonic relationship between subduction of the Izanagi–Pacific ridge and Hidaka magmatic activity. Island Arc, 30(1), e12403.
Nanayama, F. et al., 2022, Origin and evolution of the Paleo-Kuril arc inferred from detrital zircon U-Pb chronology in eastern Hokkaido, NE Asia. Island Arc, 31(1), e12458. https://doi.org/10.1111/iar.12458
Yamasaki, T. et al., 2021, Subduction of the Izanagi–Pacific Ridge–transform intersection at the northeastern end of the Eurasian Plate. Geology, 49, 952–957 https://doi.org/10.1130/G48611.1
(1) The PKA originated from an oceanic island arc on the oceanic Izanagi Plate around 85 Ma, to which the greenstone complex (Nikoro Group) 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 area 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 (Nanayama et al., 2021). It is possible that the Izanagi–Pacific Ridge collided with NE Asia during this period (Yamasaki et al., 2021).
(4) Around 40 Ma, during the deposition of coarse conglomerate beds of the Urahoro Group (Katagiri et al., 2019), the PKA was uplifted and bent clockwise due to a second collision with NE Asia.
(5) 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 (Nanayama et al., 2021, 2022).
References
Katagiri, T. et al., 2019, Collisional bending of the western Paleo-Kuril Arc deduced from paleomagnetic analysis and age determination. Island Arc, 2019, e12329.
Nanayama, F. et al., 1993, Sedimentary petrology and paleotectonic analysis of the arc-arc junction: the Paleocene Nakanogawa Group in the Hidaka Belt, central Hoikkaido, Japan. Palaeogeography, Palaeoclinatology, Palaeoecology, 105, 53-69.
Nanayama, F. et al., 2021, The emplacement of in situ greenstones in the northern Hidaka belt: the tectonic relationship between subduction of the Izanagi–Pacific ridge and Hidaka magmatic activity. Island Arc, 30(1), e12403.
Nanayama, F. et al., 2022, Origin and evolution of the Paleo-Kuril arc inferred from detrital zircon U-Pb chronology in eastern Hokkaido, NE Asia. Island Arc, 31(1), e12458. https://doi.org/10.1111/iar.12458
Yamasaki, T. et al., 2021, Subduction of the Izanagi–Pacific Ridge–transform intersection at the northeastern end of the Eurasian Plate. Geology, 49, 952–957 https://doi.org/10.1130/G48611.1