Age of the N7/N8 (M4/M5) planktonic foraminifera zone boundary: constraints from the zircon geochronology and magnetostratigraphy of early Miocene sediments in Ichishi, Japan

Hoshi, Hiroyuki; Iwano, Hideki; Danhara, Tohru; Oshida, Hikoma; Hayashi, Hiroki; Kurihara, Yukito; Yanagisawa, Yukio

doi:10.1016/j.chemgeo.2019.119333

Cited by 15 publications

(8 citation statements)

References 45 publications

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“…So, ages of the formations and members of the group could depend on areas to some extent. The above-mentioned precise ages of the Iu and Isegi Members (Figure 2) were determined along the Haze river in the central part of our study area (Hoshi, Sahashi, et al, 2019), and those of the Mitsugano Member and Katada Formation in the northeastern part (Hoshi, Iwano, et al, 2019).…”

Section: Tectonostratigraphymentioning

confidence: 92%

“…PF, planktonic foraminifer zones after Blow (1969). Stars indicate the horizons whose ages were precisely determined by Hoshi, Iwano, et al (2019). KN, Kitanagano Sandstone Member.…”

Section: Tectonostratigraphymentioning

confidence: 99%

“…The Ichishi Group is younger than ~19 Ma, and the top horizon of the group is somewhat younger than 17 Ma (Hoshi, Iwano, et al, 2019;Hoshi, Sahashi, et al, 2019). The magnetostratigraphic and micropaleontological studies by Yoshida (1991), Hoshi, Iwano, et al (2019) assign the upper part of the Oi Formation and the Katada Formation to the Chron C5Cr, and the formation boundary shortly above the boundary of the planktonic foraminifer zones, N.7 and N.8 (Figure 2). They also correlated the boundary between the Oi and Haze Formations to a lower part of the Chron C5En.…”

Section: Tectonostratigraphymentioning

confidence: 99%

“…They also correlated the boundary between the Oi and Haze Formations to a lower part of the Chron C5En. Radiometric dating of tuff beds at the top horizons of the Oi and Katada Formations indicates that the Katada Formation was accumulated within ~0.1 my (Hoshi, Iwano, et al, 2019). There is no key bed that can be traced across the Ichishi basin.…”

Section: Tectonostratigraphymentioning

confidence: 99%

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Arc‐parallel extension in preparation of the rotation of southwest Japan: Tectonostratigraphy and structures of the Lower Miocene Ichishi Group

Kinoshita

Yamaji

2021

Island Arc

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Opening of the Japan Sea back arc basin was accompanied by extensional tectonics in the drifting southwest Japan arc. Various trends of Early Miocene grabens in the arc suggest multi-directional rifting, which necessarily involved strike-slip components of some of basin-margin faults. However, such components are not well understood. In this work we conducted a field survey in the Early Miocene Ichishi basin on the northern side of the Median Tectonic Line, central southwest Japan. We found that the basin was a compound of grabens that were formed along normal and sinistral strike-slip faults, the latter of which had northeast-southwest trends. The block faulting in this phase produced basement highs between sub-basins, which were filled with the lower part of the Ichishi Group. We found a low-angle angular unconformity at a middle horizon in the group, with which we define the upper and lower part of the group. The upper part onlapped both the basement highs and the lower part. It means that the transtensional basin formation ceased sometime between 18 and 17.5 Ma in the Ichishi area. The Ichishi basin turned subsequently into a sag basin subsided due to normal faulting probably along the Nunobiki-sanchi-toen fault zone. The transtension and the basin sag were driven by ENE-WSW extensional stress. This arc-parallel extension produced grabens various areas including Ichishi in the Early Miocene. The extensional deformation was eventually localized to the deep rift along the Fossa Magna to make the lithosphere under southwest Japan decoupled from that under northeast Japan. The decoupling allowed the rapid rotation of southwest Japan from ~17.5 Ma. The cluster of those grabens around the Ise bay probably determined the southeastern margin of the Kinki triangle.

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Section: Tectonostratigraphymentioning

confidence: 92%

“…PF, planktonic foraminifer zones after Blow (1969). Stars indicate the horizons whose ages were precisely determined by Hoshi, Iwano, et al (2019). KN, Kitanagano Sandstone Member.…”

Section: Tectonostratigraphymentioning

confidence: 99%

Section: Tectonostratigraphymentioning

confidence: 99%

Section: Tectonostratigraphymentioning

confidence: 99%

See 2 more Smart Citations

Arc‐parallel extension in preparation of the rotation of southwest Japan: Tectonostratigraphy and structures of the Lower Miocene Ichishi Group

Kinoshita

Yamaji

2021

Island Arc

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“…The youngest graben is covered by a precisely dated Miocene formation in the Kinki district and is bounded by the NW‐trending Benten–Kuga Fault in the Tsu area (Figure 1). The graben is filled by tilted lower Miocene formations unconformably overlain by the Oi Formation (Wada, 1980; Yoshida et al, 1995), the upper part of which has been dated by microfossils at 18–17 Ma (Hoshi et al, 2019; Oshida, Hayashi, Yanagisawa, Kurihara, & Hoshi, 2018).…”

Section: Discussionmentioning

confidence: 99%

Termination of intra‐arc rifting at ca 16 Ma in the Southwest Japan arc: The tectonostratigraphy of the Hokutan Group

Haji

Yamaji

2020

Island Arc

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Miocene intra-arc rifting associated with the opening of the Japan Sea formed grabens in several areas in Southwest (SW) Japan, but the extensional tectonics of the arc are still not well understood. In this study, we first document the tectonostratigraphy of the Hokutan Group in the northwestern part of the Kinki district, and demonstrate the termination of extensional tectonics at ca 16.5 Ma, as inferred from grabens in the lower part of the group being unconformably overlain by sediments of the upper part. Second, we review early Miocene grabens in SW Japan to suggest that intra-arc rifting was abandoned at ca 16 Ma, essentially simultaneously with the end of rotation of the SW Japan arc as evidenced by paleomagnetic studies. The lesser numbers of grabens and reduced thicknesses of graben fills suggest that extensional deformation of the SW Japan arc was significantly weaker than that of the Northeast (NE) Japan arc, which was broken into blocks, indicating various degrees of paleomagnetic rotation within NE Japan. The weak deformation has allowed paleomagnetic studies to infer the coherent rotation of the SW Japan arc.

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Extensional stress accompanied by Miocene near-trench magmatism in the southern Kii Peninsula, SW Japan

Haji

Yamaji

Iwano³

et al. 2022

Journal of Asian Earth Sciences

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Age of the N7/N8 (M4/M5) planktonic foraminifera zone boundary: constraints from the zircon geochronology and magnetostratigraphy of early Miocene sediments in Ichishi, Japan

Cited by 15 publications

References 45 publications

Arc‐parallel extension in preparation of the rotation of southwest Japan: Tectonostratigraphy and structures of the Lower Miocene Ichishi Group

Arc‐parallel extension in preparation of the rotation of southwest Japan: Tectonostratigraphy and structures of the Lower Miocene Ichishi Group

Termination of intra‐arc rifting at ca 16 Ma in the Southwest Japan arc: The tectonostratigraphy of the Hokutan Group

Extensional stress accompanied by Miocene near-trench magmatism in the southern Kii Peninsula, SW Japan

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