Tephrochronological Study of Higashiyama Volcano at Hachijojima, Izu Islands

Sugihara, Shigeo

doi:10.5026/jgeography.107.3_390

Cited by 6 publications

(9 citation statements)

References 3 publications

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“…Previous mapping of the island misidenti ed some rock types, and distribution and orientations of tilted strata were not given. The proposed Aira-Tn tephra (Sugihara 1998) was not shown by the map distributions nor the sample locations, so these could not be reliably reproduced. Through geological mapping, we identi ed and mapped two distinct tephra (glassy tuff) layers (Figs.…”

Section: Morphological and Volcanic Geological Surveymentioning

confidence: 94%

“…The topology shows severe dissection of the Mihara-yama volcano to the extent that the original edi ce has been severely modi ed (cf., Isshiki 1959;Sugihara 1998;Suga 1998). Whereas this erosional dissection destroys the original edi ce shape (Fig.…”

Section: Morphological and Volcanic Geological Surveymentioning

confidence: 96%

“…Although dissection of the Mihara-yama volcano is extensive (Fig. 1E), previous studies on this volcano (Isshiki 1959;Tsukui et al 1991Tsukui et al , 1993Suga 1994Suga , 1998Suga et al 1997;Sugihara, 1998) were based primarily on aerial photo interpretation. The geological map by Sugihara and Shimada (1998) for the younger Hachijo-Fuji volcano appears to be inconsistent with eld relationships recorded by detailed geologic mapping of the outcrops.…”

Section: Regional Setting and Backgroundmentioning

confidence: 99%

“…A regional tephra interpreted as the 0.0275 Ma Aira-Tn tephra from the Aira caldera, southern Kyushu (Machida and Arai, 2003; See relevant regional tephra list in Table 1) was reported from the Mihara-yama succession with many radiometric 14 C data younger than 0.03 Ma (Sugihara 1998). During our preliminary eld observations, it appeared to us that the tephra did not constitute a single layer within the Mihara-yama scoria-pumice tuff successions as previously interpreted.…”

Section: Regional Setting and Backgroundmentioning

confidence: 99%

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4D volcanic geology of Hachijo-jima islet, Izu-Bonin arc

Osozawa

Ito

Nakazato

et al. 2021

International Geology Review

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This study provides geological, geochemical, and chronological insight into the evolution of the Hachijojima volcanoes of the Izu Bonin arc. The regional Ata-Torihama tephra (Ata-Th; 0.24 Ma) and Kikai-Tozurahara tephra (K-Tz; 0.095 Ma) from Kyushu are intercalated within the voluminous proximal volcanic products. Our study combines detailed geologic mapping, tephrochronology, U-Pb zircon dating, and published drill core data from NEDO (1993) to evaluate the time transgressive 3-dimensional (thus 4dimensional) structure of the dissected Mihara-yama volcano, the older of the two volcanoes on Hachijojima. The volcanic succession comprises terrestrial volcanic basement, marine volcaniclastic rocks, and terrestrial tuff intercalated with tholeiitic basalt and the regional calc-alkaline tephra layers. The undissected Hachijo-Fuji stratovolcano (tholeiitic basalt) overlies marine volcaniclastics abutting the northwestern paleo sea cliffs of Mihara-yama. Newly-described folding and normal faulting of the marine and overlying terrestrial volcaniclastic rocks suggests NW-SE shortening that may be associated with the collision of the Izu-Bonin arc with the Honshu arc. The proto Hachijo-jima volcano emerged above the sea > 0.24 Ma, and this date can be applied as a molecular biological calibration date for organisms on this island. HighlightThe erosionally-dissected Mihara-yama volcano was built on 2.1 Ma altered volcanic basement. Deposition of volcanic strata over this basement buttress unconformity began in submarine conditions at < 1.8 Ma, followed by subaerial pyroclastic ows and a tholeiitic-lava ow from 0.24 Ma onward.Emergence of the Mihara-yama volcano above sea level was > 0.24 Ma.The Ata-Torihama tephra (Ata-Th; 0.24 Ma; U-Pb age < 0.46 Ma) and Kikai-Tozurahara tephra (K-Tz; 0.095 Ma; U-Pb age < 0.24 Ma) from giant calderas of Ata and Kikai of Kyushu (calc-alkaline) are intercalated in the terrestrial scoriaceous-pumice tuffs derived from the Mihara-yama volcano (tholeiite). Previous correlations to the Aira-Tn tephra (Aira-Tanzawa; AT; 0.0275 Ma) are not viable.Adjacent to the northwestern paleo sea cliff of this old volcano, a shallow marine basin was formed at < 0.26 Ma. Subaerial scoria and tuff cones were also formed as small-scale lateral volcanoes.Tholeiitic lava ows built the subaerial Hachijo-Fuji stratovolcano over the shallow marine basin, and two major volcanoes were connected to form a single Hachijo-jima island.The island deformed by NNW-SSE shortening, re ecting the Izu-Bonin collision toward the central Japan arc.

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Section: Morphological and Volcanic Geological Surveymentioning

confidence: 94%

Section: Morphological and Volcanic Geological Surveymentioning

confidence: 96%

Section: Regional Setting and Backgroundmentioning

confidence: 99%

Section: Regional Setting and Backgroundmentioning

confidence: 99%

See 2 more Smart Citations

4D volcanic geology of Hachijo-jima islet, Izu-Bonin arc

Osozawa

Ito

Nakazato

et al. 2021

International Geology Review

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“…A d v a n c e P u b l i c a t i o n A r t i c l e ed at~10-13 ka (e.g., Nakano et al, 1991Nakano et al, , 1997Ishizuka et al, 2008;Saito et al, 2019), based on the tephra chronology of the Higashiyama volcano (Hayakawa, 1990;Tsukui et al, 1991;Sugihara, 1998). According to Suga (1998), the volcanic activity of the Nishiyama volcano can be divided into the following stages: the pre-caldera forming (13-4 ka), the Kando-yama tuff cone forming (Kando-yama surge deposit), the syn-caldera forming (buried caldera at the Nishiyama mountainside), and the post-caldera forming stages (the formation of the main stratovolcano and the scoria cones at the southern foot of the Nishiyama volcano).…”

Section: Geologymentioning

confidence: 99%

Anorthosites in Nishiyama volcanic products from the Hachijo–jima island, Izu–Bonin arc: The direct evidence for ‘plagioclase control’ in shallow magma reservoir

Aizawa

Saito²,

Imura

et al. 2020

Journal of Mineralogical and Petrological Sciences

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The Nishiyama volcano is a Quaternary stratovolcano consisting of the northwestern part of the Hachijo-jima island, located in a volcanic front of the Izu-Bonin arc. The Holocene activity of the Nishiyama volcano began at~10-13 ka and has mainly produced basaltic lava flows and scoria fall deposits. While gabbroic and doleritic enclaves are generally found in scoriaceous pyroclasts, we discovered anorthositic enclaves in the lava flows.Here, we report the petrographical and petrological characteristics of the anorthositic enclaves. In the basaltic lava flows, the amount of plagioclase phenocrysts positively correlated with the whole-rock content of Al 2 O 3 , CaO, and Sr with these elements preferentially contained in the feldspar. In addition, an ideal anorthite content obtained from the whole-rock chemistry of the basaltic lava flows (An 88 ) was largely consistent with the measured anorthite content obtained from anorthosite (An 84 ). These results suggest that the plagioclase fractionation and/or accumulation controls the whole-rock chemical composition of basaltic lava flows and that the accumulated plagioclases represent part of anorthositic enclaves. Anorthosite was divided into three types of textures: 1) Comb texture, 2) adcumulate texture, and 3) radial texture. These textures (from the comb texture to the radial texture) reflected the change in the undercooling state of the magma. Based on the petrography of the anorthosite and lava flows, the plagioclase was in a liquidus phase in the Nishiyama basaltic magma. Additionally, the anorthosite was formed by the effects of adiabatic ascent and the degassing of near-H 2 O-saturated magma at the shallow magma reservoir (~5 km in depth) beneath the Nishiyama volcano.

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Evolutionary history of inshore oceanic island land snails diversified in shell colour

Ito

Chiba

Konuma

2023

Journal of Biogeography

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AimOceanic islands provide an excellent opportunity to study the mode and tempo of phenotypic evolution of terrestrial organisms. Many studies have focused on oceanic islands far from the mainland. Oceanic islands near the mainland may provide distinct perspectives on phenotypic evolution, but a comprehensive understanding is still lacking. To address this gap, this study aimed to reveal when a land snail species inhabiting a volcanic archipelago within 40 km of the mainland diverged and how their shell colours evolved.LocationSouthern Izu Peninsula and five Izu Islands (Oshima, Toshima, Niijima, Shikine and Kozu), Japan.Taxon Euhadra peliomphala simodae. MethodsDouble‐digest restriction site‐associated DNA sequencing (ddRAD‐seq) was conducted using 117 individual snails. Molecular phylogenetic and population genomic analyses were performed, including approximation Bayesian computation (ABC). We then examined whether the island area, elevation, distance from the surrounding landmasses and historical event (bottleneck) explain the shell colour diversity on each island using a phylogenetic generalised linear mixed model (PGLMM).ResultsSnails could be genetically categorised according to the island they inhabited, and on Niijima, their genetic structure was further divided within the island. The divergence times among the extant populations of the snail dated back to 2.1 million years ago (Ma), which is older than that of other animals occurring in this region. Additionally, island elevation positively affected shell colour diversity, and populations with similar shell colour profiles were phylogenetically different.Main conclusionsIsland land snails diversified early in the ecosystem of the Izu Islands. This suggests that proximity to the mainland, immobility and the physiological tolerance of passive dispersal in land snails were the main causes of early diversification. Moreover, our study proposes that environments covarying with elevation would determine shell colour diversity on each island through natural selection.

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Tephrochronological Study of Higashiyama Volcano at Hachijojima, Izu Islands

Cited by 6 publications

References 3 publications

4D volcanic geology of Hachijo-jima islet, Izu-Bonin arc

4D volcanic geology of Hachijo-jima islet, Izu-Bonin arc

Anorthosites in Nishiyama volcanic products from the Hachijo–jima island, Izu–Bonin arc: The direct evidence for ‘plagioclase control’ in shallow magma reservoir

Evolutionary history of inshore oceanic island land snails diversified in shell colour

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