Evolution of the Komiji Syncline in the North Fossa Magna, central Japan: Paleomagnetic and K–Ar age insights

Niitsuma, Sachiko; Niitsuma, Nobuaki; Saito, Kazuo

doi:10.1046/j.1440-1738.2003.00397.x

Cited by 14 publications

(7 citation statements)

References 23 publications

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“…This implies that the collision of the Tanzawa and Izu blocks did not play an important role in the deformation of the North Fossa Magna. In a recent study, Niitsuma et al . (2003) reported that the formation of the Komiji Syncline in the North Fossa Magna occurred in the period of 4.42–1.65 Ma.…”

Section: Introductionmentioning

confidence: 93%

Rapid tectonics of the Late Miocene Boso accretionary prism related to the Izu–Bonin arc collision

Yamamoto

Kawakami

2005

Island Arc

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The structure, paleomagnetism and biostratigraphy of the Nishizaki and Kagamigaura formations on the southern Boso Peninsula, central Japan, were investigated to determine the chronographic constraints on the accretion, post-Late Miocene rotation and regional tectonics in the Izu-Bonin island arc collision zone. The geological structures on the southern Boso Peninsula are characterized by an east-west trending and south-verging fold and thrust belt that curves toward the northwest-southeast in the northwest extent of the Nishizaki Formation. Two stages of tectonic rotation were revealed by paleomagnetic and structural studies. The first is believed to have occurred after the accretion of the Nishizaki Formation and before the deposition of the Kagamigaura Formation, while the second is confidently correlated with the 1 Ma Izu block collision. The northwest extent of the Nishizaki Formation was rotated clockwise by approximately 65-80 ∞ , whereas the rotation was only 25-30 ∞ in the east, and 11-13 ∞ in the overlying Kagamigaura Formation. Radiolarian biostratigraphy suggests a depositional age of 9.9-6.8 Ma (Upper Miocene period) for the Nishizaki Formation and 4.19-3.75 Ma (Pliocene period) for the lower Kagamigaura Formation. These results indicate that the age of accretion and first-stage rotation of the Nishizaki Formation can be constrained to the interval of 6.80-3.75 Ma. This structure most likely represents the northward bending caused by collisions of the Tanzawa and Izu blocks with the Honshu island arc, and suggests rapid processes of accretion, collision, uplift and the formation of new sedimentary basins within a relatively short period of time (2.61-3.05 my).

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Section: Introductionmentioning

confidence: 93%

Rapid tectonics of the Late Miocene Boso accretionary prism related to the Izu–Bonin arc collision

Yamamoto

Kawakami

2005

Island Arc

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“…1a. The Tanzawa block is situated in the Izu Collision Zone, where the Izu-Bonin-Mariana (IBM) arc has collided with the Honshu arc (Matsuda 1978;Niitsuma et al 2003;Yamamoto et al 2009). The IBM arc is believed to be the major site of continental crust formation.…”

Section: Geology and Samplingmentioning

confidence: 99%

Rock-magnetic properties of single zircon crystals sampled from the Tanzawa tonalitic pluton, central Japan

Sato

Yamamoto

et al. 2015

Earth Planet Sp

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This paper reports on the rock-magnetic properties of single zircon crystals, which are essential for future work establishing the reliable paleointensity method using single zircon crystals. Zircon crystals used in this study were sampled from the Nakagawa River, which crosses the Tanzawa tonalitic pluton in central Japan. Rock-magnetic measurements were conducted on 1037 grains of zircons, but many of these measurements are below the limits of the sensitivity of the magnetometers employed. Isothermal remanent magnetizations (IRMs) of 876 zircon crystal are below the practical resolution of this study; we infer that these crystals contain no or only minute quantities of ferromagnetic minerals. The other zircon crystals contain enough magnetic minerals to be measured in the DC SQUID magnetometer. Am 2 (80 zircons), combining the rock-magnetic parameter, we proposed the sample-selection criteria for future study of paleointensity experiments using single zircon crystals. In the case that the samples had high coercivity (B c ) values (>10 mT) or high M NRM /M IRM values (>~0.1), main remanence carriers are probably pyrrhotite and these samples are inappropriate for the paleointensity study. In the case that the samples had low B c values (<10 mT) and low M NRM /M IRM values (<~0.1), main remanence carriers seem to be nearly pure magnetite with pseudo-single-domain grain sizes, and these samples are expected to appropriate for the paleointensity study. Total thermoremanent magnetization (TRM) acquisition experiments were also carried out for 12 samples satisfying the above criteria. The TRM intensity was comparable with that of NRM, and a rough estimation of the paleointensity using NRM/TRM ratios shows field intensities consistent with the average geomagnetic field intensity at the Tanzawa tonalitic pluton for last 5 Myr.

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“…As for the evolution of folded structures, based on paleomagnetic and chronological studies, Niitsuma et al (2003) reported the mid-Pliocene sinistral rotation in axial directions from a NE-SW trend to a N-S trend, suggesting basement wrenching since 4 Ma. The counter-clockwise rotation of fold axes in MB occurred on the southwestern side of the Chikumagawa Tectonic Line (Takeuchi, 1978; facing arrows in Fig.…”

Section: Pliocene and Later Compression Regimementioning

confidence: 99%

Basement-involved tectonics in North Fossa Magna, central Japan: The significance of the northern Itoigawa-Shizuoka Tectonic Line

Takeuchi

2014

Earth Planet Sp

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The Toyama Trough and Fossa Magna basin are major transverse tectonic depressions located between northeast Japan (NEJ) and southwest Japan (SWJ). Itoigawa-Shizuoka Tectonic Line (ISTL), the western margin of Fossa Magna is a boundary between two tectonic provinces along the inner side of NEJ and SWJ. Abrupt lateral variations in thickness of the Middle to Upper Miocene strata are quite significant among these provinces in the North Fossa Magna. The development of the thrust/fold belt is attributed not only to horizontal compression but also to vertical block movements as basement-involved tectonics. In response to the Pliocene and later compression regime, the old fault-block boundaries were reactivated and produced differential block movement such as the tilting of the Central Upheaval Zone and uplifting of the Nishikubiki Belt. One possible model for the deeper geologic structure is presented that high-angled block faults on the surface among tectonic provinces originate in vertical weak zones in the deep seismogenic zone under the sedimentary layer. The folded Neogene system comprises the present-day thrust-fault province of the North Fossa Magna and the stress regime of strikeslip faulting occupies the basement, as inferred from focal mechanism solutions for small events. In order to account for the apparent discrepancy, a duplex stress field is possible for the active tectonics in the region.

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Evolution of the Komiji Syncline in the North Fossa Magna, central Japan: Paleomagnetic and K–Ar age insights

Cited by 14 publications

References 23 publications

Rapid tectonics of the Late Miocene Boso accretionary prism related to the Izu–Bonin arc collision

Rapid tectonics of the Late Miocene Boso accretionary prism related to the Izu–Bonin arc collision

Rock-magnetic properties of single zircon crystals sampled from the Tanzawa tonalitic pluton, central Japan

Basement-involved tectonics in North Fossa Magna, central Japan: The significance of the northern Itoigawa-Shizuoka Tectonic Line

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