Distinguishing reworked diatoms derived from Neogene marine strata in modern coastal assemblages for understanding taphonomic processes and reconstructing Holocene paleoenvironments in the Tokachi coastal area, Hokkaido, Japan

Chiba, Takashi; Nishimura, Yuichi; Yanagisawa, Yukio

doi:10.1016/j.marmicro.2021.101970

Cited by 4 publications

(2 citation statements)

References 49 publications

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“…For the classification of diatom species, we considered factors such as salinity (ranging from marine, marine–brackish, brackish, brackish–freshwater, to freshwater) and life form (comprising planktonic, epontic, and benthic categories), drawing on ecological references [ 32 , 35 , 44 – 46 ]. Diatoms from the Neogene period along the Hidaka coast, as reported by Sagayama et al [ 47 ], were excluded from the assemblage analysis due to their allochthonous contribution linked to the erosion of older deposits [ 48 ]. Moreover, we exclusively included species constituting more than 3% of the total, considering them significantly present for the subsequent diatom assemblage analysis, while disregarding less common species.…”

Section: Methodsmentioning

confidence: 99%

Understanding paleo-earthquakes in the Kuril Trench based on Late-Holocene tsunami deposits in the distal region from wave sources, northern Hidaka, Hokkaido, Japan

Nakanishi,

Ashi,

Okamura

et al. 2024

PLoS ONE

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Geological evidence, such as tsunami deposits, is crucial for studying the largest rupture zone of the Kuril Trench in Hokkaido, Japan, due to its poor historical record. Although 17th-century tsunami deposits are widely distributed across Hokkaido, the presence of multiple wave sources during that period, including the collapse of Mt. Komagatake, complicates the correlation with their wave sources. Understanding the regional distribution of these tsunami deposits can provide valuable data to estimate the magnitude of megathrust earthquakes in the Kuril Trench. The northern part of Hidaka, Hokkaido, where tsunamis from multiple wave sources are expected to overlap, is distant from the Kuril Trench. To clarify the depositional history of tsunami deposits in such distal areas, evaluating the influence of the depositional environments on the event layer preservation becomes even more critical. We conducted field surveys in Kabari, located in the northern Hidaka region, identifying three sand layers from the 10th to the 17th century and two layers dating beyond 2.3 thousand years ago. The depositional ages of most sand layers potentially correlate with tsunami deposits resulting from the Kuril Trench earthquakes. Utilizing reconstructed paleo-sea level data, we estimated that most sand layers reached approximately 2 m in height. However, it is noteworthy that the latest sand layer from the 17th century exhibited an unusual distribution, more than 3 m in height. This suggests a different wave source as the Mt. Komagatake collapse. The discovery of multiple sand layers and their distributions is crucial to constraining the maximum magnitude of giant earthquakes in the Kuril Trench and understanding the volcanic tsunami events related to Mt. Komagatake.

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Section: Methodsmentioning

confidence: 99%

Understanding paleo-earthquakes in the Kuril Trench based on Late-Holocene tsunami deposits in the distal region from wave sources, northern Hidaka, Hokkaido, Japan

Nakanishi,

Ashi,

Okamura

et al. 2024

PLoS ONE

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“…(2005) to inhabit freshwater environments, not necessarily implying the transport from a marine habitat. In addition, Delphineis sp., Palaria sulcate , Thalassionema niztschioides , and Thalassiosira lineata are found as fossil species in Neogene formations (e.g., Akiba, 1986), which may not directly suggest transport from a marine environment (Chiba et al., 2021). Because the hinterland of the study area consists of the Paleocene sedimentary rocks, it is unlikely that the rocks containing these fossil species were directly transported to the peatland.…”

Section: Description Of Tsunami Depositsmentioning

confidence: 99%

Spatial Extent of Mid‐To Late‐Holocene Sedimentary Record of Tsunamis Along the Southern Kuril Trench, Hokkaido, Japan

Nakanishi

Ashi

Miyairi

et al. 2022

Geochem Geophys Geosyst

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With their complex cycles and rupture modes, infrequent megathrust earthquakes require a high‐resolution spatiotemporal record of tsunami inundations over thousands of years to provide more accurate long‐term forecasts. The geological record suggests that Mw > 8 earthquakes in the Kuril Trench occurred at intervals of several hundred years. However, uncertainties remain regarding the rupture zone, owing to the limited survey areas and chronological data. Therefore, we investigated the tsunami deposits in a coastal wetland of southeastern Hokkaido, Japan, to characterize the tsunamis that originated from the Kuril Trench over the last 4,000 years. On the Erimo coast, more than seven sand layers exhibited common features of tsunami deposits, such as sheet distributions of several hundred meters, normal grading structures, and sharp basal contacts. According to numerical tsunami simulations, the 17th‐century sand layer could be reproduced using a multiple rupture zone model (Mw ∼ 8.8). We used high‐resolution radiocarbon dating and tephras to correlate the tsunami deposits from the last 4,000 years with those reported from regions ∼100 km away. The tsunami history revealed here shows good agreement with the histories of adjacent regions. However, the paleotsunamis reported to have occurred in regions >200 km away include events that differ from those in this study, suggesting a diversity of Mw > 8 earthquakes in the Kuril Trench. We clarified the history and extents of earthquake‐generated tsunamis along the southwestern end of the Kuril Trench, which were previously unknown. Our results provide a framework for magnitude estimations and long‐term forecasts of earthquakes.

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Unraveling the palaeoecology of Paralia sulcata-dominated assemblages from Late Miocene marine deposits of Patagonia (South Atlantic, Argentina)

Allende Mosquera,

Fayó,

Vélez-Agudelo

et al. 2024

Marine Micropaleontology

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Distinguishing reworked diatoms derived from Neogene marine strata in modern coastal assemblages for understanding taphonomic processes and reconstructing Holocene paleoenvironments in the Tokachi coastal area, Hokkaido, Japan

Cited by 4 publications

References 49 publications

Understanding paleo-earthquakes in the Kuril Trench based on Late-Holocene tsunami deposits in the distal region from wave sources, northern Hidaka, Hokkaido, Japan

Understanding paleo-earthquakes in the Kuril Trench based on Late-Holocene tsunami deposits in the distal region from wave sources, northern Hidaka, Hokkaido, Japan

Spatial Extent of Mid‐To Late‐Holocene Sedimentary Record of Tsunamis Along the Southern Kuril Trench, Hokkaido, Japan

Unraveling the palaeoecology of Paralia sulcata-dominated assemblages from Late Miocene marine deposits of Patagonia (South Atlantic, Argentina)

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