Miocene–Holocene volcanism

Nakada, Setsuya; Yamamoto, Takahiro; Maeno, Fukashi

doi:10.1144/goj.11

Cited by 12 publications

(13 citation statements)

References 111 publications

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“…They are associated with huge pyroclastic flow deposits, debris, and tephra that were erupted by large-scale caldera-forming processes; they comprise only 17% of the area. In particular, Aso and Ito pyroclastic rocks erupted from the Aso and Aira calderas mainly about 90 ky and 29 ky ago, respectively; they are distributed widely in the central and the southern parts, respectively (Nakada et al 2016). The Kikai caldera to the south of the Kyushu mainland was formed by large-scale violent eruptions 7.3 ky ago.…”

Section: Terrestrial Geology and Metalliferous Depositsmentioning

confidence: 99%

“…An analysis of variance (ANOVA) and Bonferroni's multiple comparison test were applied to the geochemical data sets to objectively examine the influence of lithology on the chemical compositions of stream sediments (Hochberg & Tamhane 1987;Nagata & Yoshida 1997;Miller & Miller 2010). These statistical tests assume that the data follow a normal distribution.…”

Section: Differences In Elemental Concentrations Of Stream Sediments mentioning

confidence: 99%

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Application of spatial distribution patterns of multi-elements in geochemical maps for provenance and transfer process of marine sediments in Kyushu, western Japan

Ohta¹,

Imai²,

Tachibana³

et al. 2020

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We investigated the origin of marine sediments and their transfer by water currents using the spatial distribution patterns of multi-elements in terrestrial and marine areas of Kyushu, western Japan. Quaternary volcanic material covers Cretaceous granitic rock and Jurassic-Paleogene sedimentary rock of an accretionary complex in this region. Cluster analysis based on chemical compositions identified the origin of marine sediments from stream sediments originating from the above lithologies. Pyroclastic flow deposits associated with caldera formation, particularly that of the Kikai caldera (7.3 ka), were characterized by low Cr/Ti and La/Yb ratios. In contrast, the La/Yb ratio was very high in sediments derived from granitic rock and sedimentary rock of the accretionary complex. The spatial distributions of low Cr/Ti and La/Yb ratios suggest that marine sediments containing pyroclastic materials, which are found within an 80-km radius of the Kikai caldera, were distributed on the shelf and transported northeastward by a branch of the Kuroshio Current. The continuous distribution of the medium Cr/Ti and high La/Yb ratios from the land to the coast, slope, and deep basin on the Pacific Ocean side suggests that sediments supplied from the terrestrial area were transferred by gravitational transport from the shelf to the deep basin.

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Section: Terrestrial Geology and Metalliferous Depositsmentioning

confidence: 99%

Section: Differences In Elemental Concentrations Of Stream Sediments mentioning

confidence: 99%

Application of spatial distribution patterns of multi-elements in geochemical maps for provenance and transfer process of marine sediments in Kyushu, western Japan

Ohta¹,

Imai²,

Tachibana³

et al. 2020

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“…The late Miocene to Quaternary arcs of NE and SW Japan and Quaternary (and possibly older) Izu-Bonin arc are also characterized by extensive ash-flow caldera development (Takahashi, 1986; Miura & Wada, 2007;Tamura et al, 2009;Mahony et al, 2011;Yoshida et al, 2014;Nakada et al, 2016), with >80 calderas averaging~10 km across estimated to have erupted in NE Japan alone from 8-1.7 Ma (Yoshida et al, 2014;Fig. 3b).…”

Section: Volcano-plutonic Stylementioning

confidence: 99%

“…Major ash-flow caldera flare-ups in Japan: (a) Cretaceous-Paleogene arcs of SW Japan (afterNakada et al, 2016), and (b) late Miocene-Quaternary arc of NE Japan (afterYamamoto, 2009). Quaternary stratovolcanoes of NE Japan also shown (afterYamamoto, 2009).…”

mentioning

confidence: 99%

Why No Porphyry Copper Deposits in Japan and South Korea?

Sillitoe¹

2018

Resource Geology

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This analysis concludes that there is little realistic likelihood of discovering large, high‐grade porphyry Cu deposits in Japan and South Korea because of an unusual combination of geological factors. First, weak inter‐plate coupling, trench retreat, and extension – a tectonic regime unfavorable for porphyry Cu formation – appears to have characterized the convergent margin during much of Cretaceous through Neogene time. Second, Cretaceous through Quaternary magmatism involved widespread ash‐flow caldera development, a volcanic style that suppresses porphyry Cu formation because the all‐important Cu‐bearing magmatic fluids – if present – would be explosively discharged during silicic ignimbrite eruption and lost to the atmosphere. Third, due to the trench retreat, crustal profiles beneath Japan are dominated by accretionary complexes containing chemically reduced lithologies, which decrease the redox state of subduction‐related magmas during their ascent. The most reduced intrusions belong to the ilmenite‐series, which may lock up chalcophile elements at depth and produce magmatic fluids that are incapable of transporting the Cu required for significant porphyry deposit formation. Fourth, many of the caldera‐related magmatic rocks, including the principal intrusions, are not only derived by partial melting of reduced crust but are commonly also highly fractionated; hence, any associated mineralization tends to be Mo ± W‐rich rather than Cu dominated. Fifth, intrusive rocks with high Sr/Y, typical of hydrous magmas responsible for porphyry Cu belts worldwide, appear to be present only locally. Sixth, two important magmatic and metallogenic tracts in Japan, the Kuroko‐bearing Green Tuff belt and Kitami low‐sulfidation epithermal Au region, are characterized by bimodal magmatism, which worldwide is compositionally unsuited to porphyry Cu generation. Seventh, the Pliocene‐Quaternary andesitic–dacitic volcanoes that could be the surface expressions of porphyry Cu systems are mostly too shallowly eroded to reveal underlying deposits should they exist. Consequently, few magmatic suites in Japan and South Korea provide propitious environments for porphyry Cu exploration, with the last hope believed to lie at depth below late Miocene–Pliocene advanced argillic lithocaps, several of which contain relatively minor high‐sulfidation epithermal Au mineralization. However, even there, the reduced crust may have militated against effective Cu transport into the porphyry environment. The magmatic and metallogenic factors that downgrade the porphyry Cu potential of Japan and South Korea are believed to be equally applicable to other subduction‐related magmatic arc segments worldwide.

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“…There is an alternative, integrative hypothesis proposing that grassland and its biodiversity, which flourished during the LGM partially due to the volcanic ash falls [8,23], were destined to decline with the increased temperature and humidity after the LGM. However, since then, Neolithic people had maintained grasslands to facilitate hunting by intentional burning.…”

Section: Introductionmentioning

confidence: 99%

Genomic reconstruction of 100 000-year grassland history in a forested country: population dynamics of specialist forbs

et al. 2019

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Grassland ecosystems worldwide have been extensively converted to other land uses and are globally imperiled. Because many grasslands have been maintained by human activities, understanding their origin and history is fundamentally important to better contemporary management. However, existing methods to reconstruct past vegetation can produce contrasting views on grassland history. Here, we inferred demographic histories of 40 populations of four grassland forb species throughout Japan using high-resolution genome sequences and model-flexible demographic simulation based on the site frequency spectrum. Although two species showed a slight decline in population size between 100 000–10 000 years ago, our results suggest that population sizes of studied species have been maintained within the range of 0.5–2.0 times the most recent estimates for at least 100 000 years across Japan. Our results suggest that greater than 90% declines in Japanese grasslands and subsequent losses of grassland species in the last 100 years are geologically and biologically important and will have substantial consequences for Japanese biota and culture. People have had critical roles in maintaining disturbance-dependent grassland ecosystems and biota in this warm and wet forested country. In these contexts, disturbances associated with forest harvesting and traditional extensive farming have the potential to maintain grassland ecosystems and can provide important opportunities to reconcile resource production and conservation of grassland biodiversity.

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Miocene–Holocene volcanism

Cited by 12 publications

References 111 publications

Application of spatial distribution patterns of multi-elements in geochemical maps for provenance and transfer process of marine sediments in Kyushu, western Japan

Application of spatial distribution patterns of multi-elements in geochemical maps for provenance and transfer process of marine sediments in Kyushu, western Japan

Why No Porphyry Copper Deposits in Japan and South Korea?

Genomic reconstruction of 100 000-year grassland history in a forested country: population dynamics of specialist forbs

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