The Quaternary Kurobegawa Granite: an example of a deeply dissected resurgent pluton

Ito, Hisatoshi; Adachi, Yoshiko; Cambeses, Aitor; Беа, Ф.; Fukuyama, Mayuko; Fukuma, Koji; Yamada, Ryūji; Kubo, Takashi; Takehara, Mami; Horie, Kenji

doi:10.1038/s41598-021-01562-2

Cited by 6 publications

(19 citation statements)

References 59 publications

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“…Granite samples with slightly older U–Pb zircon ages (ca. 1.4–1.0 Ma) are also reported throughout the pluton (Harayama, 2015; Ito et al, 2013, 2017, 2021; Spencer et al, 2019). This westward‐younging trend is also confirmed by KAr biotite ages and fission‐track zircon ages (Harayama, 2015).…”

Section: Geological Settingmentioning

confidence: 88%

“…They also applied the hornblende-plagioclase geothermometer of Holland & Blundy (1994) to the magnesiohornblende rim and plagioclase rim with oligoclase composition, confirming that the estimated pressure-temperature (P-T) conditions are plotted on the haplogranite solidus within error (Ito et al, 2021). However, they could not estimate the solidification pressure condition of the host granite itself because amphibole was absent in the rock matrix (Ito et al, 2021).…”

Section: Geological Settingmentioning

confidence: 97%

“…Geochronological studies have suggested that the Kurobegawa Granite is the youngest exposed pluton in the world (e.g., Ito et al, 2013Ito et al, , 2017Ito et al, , 2021Spencer et al, 2019). The youngest U-Pb zircon ages (ca.…”

Section: Geological Settingmentioning

confidence: 99%

“…Meanwhile, the magnesiohornblende rim was interpreted as having crystallized under progressively oxidized condition during the second boiling of residual melt and the transformation of sulfur species from SO 2 to H 2 S within the MMEs on cooling (Yamaguchi et al, 2003). Ito et al (2021) recently estimated the solidification pressure condition of a MME sample from the boundary between the lower and middle units as 0.17 ± 0.02 GPa, by applying the Al‐in‐hornblende geobarometer of Mutch et al (2016) to the magnesiohornblende rim. They also applied the hornblende‐plagioclase geothermometer of Holland & Blundy (1994) to the magnesiohornblende rim and plagioclase rim with oligoclase composition, confirming that the estimated pressure–temperature ( P – T ) conditions are plotted on the haplogranite solidus within error (Ito et al, 2021).…”

Section: Geological Settingmentioning

confidence: 99%

“…The MMEs are distributed densely throughout the pluton and generally contain amphibole and all mineral assemblages required to apply Al‐in‐hornblende geobarometers (Wada et al, 2004; Yamaguchi et al, 2003). Also, it is reported that U–Pb zircon ages of a MME and its host granite are within uncertainty of analysis and thus they were formed almost coevally (Ito et al, 2017, 2021). However, the solidification pressure condition of the Kurobegawa Granite itself has not been evaluated by petrological studies yet (Ito et al, 2021; Yamaguchi et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

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Solidification pressures and ages recorded in mafic microgranular enclaves and their host granite: An example of the world's youngest Kurobegawa granite

et al. 2022

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Solidification pressures and ages of mafic microgranular enclaves (MMEs) and their host granite were determined and compared based on Al‐in‐hornblende geobarometry and U–Pb zircon dating in two sample localities in the Kurobegawa Granite. In sample KRG19‐A03 from the middle unit of the pluton, the MME and the host granite yielded 0.18 ± 0.03 to 0.24 ± 0.04 GPa and 0.16 ± 0.03 to 0.23 ± 0.04 GPa, respectively. The MME and the host granite of sample KRG19‐B08b from the lower unit, respectively, yielded 0.12 ± 0.02 to 0.21 ± 0.03 GPa and 0.13 ± 0.02 to 0.18 ± 0.03 GPa. In each sample locality, the estimated solidification pressures of the MME and its host granite overlap. The weighted mean ages were calculated as 0.775 ± 0.045 Ma and 0.831 ± 0.055 Ma for the MME and the host granite of KRG19‐A03, respectively. The MME and the host granite of KRG19‐B08b, respectively, yielded 0.672 ± 0.033 Ma and 0.735 ± 0.042 Ma. The ages for MMEs tend to be younger than the host granites, although they overlap within uncertainty. Zircon commonly occurs as the matrix minerals in both lithologies, meanwhile, zircon also occurs as early phases in plagioclase cores only in the host granites. Such differences in mode of occurrence of zircon suggest that the age variation reflects the differences in timing of zircon crystallization between the lithologies. Therefore, the MMEs record the same solidification pressures as the host granites and better represent the final solidification timing of the pluton. From these data of the MMEs, an average exhumation rate of each sample locality was estimated as 7.1–14.5 mm/year (KRG19‐A03) and 5.5–14.4 mm/year (KRG19‐B08b). These exhumation rates are much larger than that of the ca. 5.6–5.2 Ma Shiaidani Granodiorite (0.93–2.5 mm/year), implying that drastic change of the exhumation rate took place between ca. 5.2 Ma and ca. 0.83 Ma.

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