Petrology and geochemistry of a calcic and ferrous granitoid pluton: the Mitsuhashi Granite in the Ryoke Belt, southwest Japan.

Kutsukake, Toshio

doi:10.2465/ganko.92.231

Cited by 8 publications

(4 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The marginal facies yielded CHIME monazite ages of ca 86–85 Ma (Morishita & Suzuki, ). The Mitsuhashi granodiorite mainly consists of Hbl−Bt tonalite and granodiorite (Kutsukake, ) with a CHIME monazite age of ca 84 Ma (Suzuki et al, , ). The Inagawa granite is composed of Hbl−Bt granodiorite and Bt granite, and is subdivided into four petrographic types based on texture and modal abundance of biotite and hornblende (Nakai, ).…”

Section: Geological Setting and Previous Studiesmentioning

confidence: 99%

Age gap between the intrusion of gneissose granitoids and regional high‐temperature metamorphism in the Ryoke belt (Mikawa area), central Japan

et al. 2017

View full text Add to dashboard Cite

The relationships between the intrusion of gneissose granitoids and the attainment of regional high‐T conditions recorded in metamorphic rocks from the Ryoke belt of the Mikawa area, central Japan, are explored. Seven gneissose granitoid samples (tonalite, granodiorite, granite) were collected from three distinct plutonic bodies that are mapped as the so‐called “Older Ryoke granitoids.” Based on bulk‐rock compositions and U–Pb zircon ages obtained by laser ablation inductively coupled plasma mass spectrometry, the analyzed granitoids can be separated into two groups. Gneissose granitoids from the northern part of the area give weighted mean 206Pb/238U ages of 99 ±1 Ma (two samples) and 95 ±1 Ma (one sample), whereas those from the southern part yield 81 ±1 Ma (two samples) and 78–77 ±1 Ma (two samples). Regional comparisons allow correlation of the northern granitoids (99–95 Ma) with the Kiyosaki granodiorite, and mostly with the Kamihara tonalite found to the east. The southern granitoids are tentatively renamed as “78–75 Ma (Hbl)−Bt granite” and “81–75 Ma Hbl−Bt tonalite” (Hbl, hornblende; Bt, biotite). and seem to be broadly coeval members of the same magmatic suite. With respect to available age data, no gneissose granitoid from the Mikawa area shows a U–Pb zircon age which matches that of high‐T metamorphism (ca 87 Ma). The southern gneissose granitoids (81–75 Ma), although they occur in the highest‐grade metamorphic zone, do not seem to represent the heat source which produced the metamorphic field gradient with a low dP/dT slope.

show abstract

Section: Geological Setting and Previous Studiesmentioning

confidence: 99%

Age gap between the intrusion of gneissose granitoids and regional high‐temperature metamorphism in the Ryoke belt (Mikawa area), central Japan

et al. 2017

View full text Add to dashboard Cite

show abstract

“…To the north, a composite pluton with 8 km E-W and 9 km N-S occurs also in the sillimanite metamorphic zone, which is the classic site where Koide (1958) proposed Mitsuhashi and Kiyosaki Granodiorites, which are followed by Kutsukake (1997aKutsukake ( , 2001. These granitoids seem to constitute one single pluton intruding into the Ryoke metamorphic rocks, and thus is called Mitsuhashi pluton in this paper.…”

Section: Plutonic Rocks In the Southmentioning

confidence: 99%

Chemical compositions of the late Cretaceous Ryoke granitoids of the Chubu District, central Japan – Revisited

Ishihara¹

2007

Bull. Geol. Surv. Japan

View full text Add to dashboard Cite

Late Cretaceous plutonic rocks of 6 gabbroids, and 75 granitoids, all belonging to ilmenite series, were re-examined by polarized XRF method. The gabbroids are relatively abundant in the south of the studied region, implying more in-put of heat and mafic magmas from the upper mantle to the lower crust. The MgO/Fe2O3 ratio of the gabbroids reveal regional variation being MgO-rich to the south, which would reflect generation depth of the mafic magmas. The granitoids are classified into I type and S type. The I-type granitoids occur most widely and divided into five zones. Their average silica contents vary from the Median Tectonic Line to the north as follows: Shinshiro-Shitara zone (60.1 % SiO2), Asuke zone (64.2 %), Toyota-Akechi zone (70.0 %), Sanagesan-Obara zone (73.9 %) and Seto zone (75.2 %). This regional variation was considered to reflect chemical heterogeneity of the infracrustal source rocks, rather than the magmatic differentiation.Granitoids of the Okazaki-Busetsu zone, represented by garnet-bearing muscovite-biotite granites, occur in the highest metamorphic grade zone, and is felsic (average SiO2 70.2 %), peraluminous (A/CNK over 1.1), and thus be called S type. Because of the highest heat flow rate in the OkazakiBusetsu zone, even supracrustal rocks were converted to magmas and formed the S-type granites. Both I and S type granitoids are often heterogeneous in the foliated parts, as compared with massive granitoids of non-metamorphic terrains. The heterogeneity can be considered due to different original compositions of the source materials and/or formed by differential regional stress during the flow movement of the solidifying magmas. Lack of hydrothermal mineralization in the south where metamorphic roof-pendent still remain, can be explained by a deep emplacement level ( 15 km) and small degree of fractionation of these granitic magmas.

show abstract

“…However, samples collected from the Kiyosaki granitoid body are missing from the dataset. Among the dataset compiled by Haraguchi et al (2017), about 14 articles and 226 sample datasets are related to the area of interest (Yuhara and Kagami, 1995;Kutsukake, 1997;Yuhara and Kagami, 1999;Ishihara and Wu, 2001;Yuhara et al, 2004aYuhara et al, , 2004bIshihara, 2005;Yuhara and Kagami, 2006;Ishihara and Murakami, 2006;Yuhara and Kagami, 2007;Ishihara and Chappell, 2007;Yuhara and Kagami 2008;Yuhara, 2011;Yuhara and Kagami, 2012). Treatment of compositional data generally faces the constant-sum constraint, although this can be avoided using logratio transformation (e.g., Aitchison, 1986).…”

Section: Application To the Natural Dataset Of Granitoidsmentioning

confidence: 99%

GEOFCM: a new method for statistical classification of geochemical data using spatial contextual information

Yoshida

Kuwatani

Yasumoto

et al. 2018

Journal of Mineralogical and Petrological Sciences

View full text Add to dashboard Cite

Conventional clustering algorithms such as k-means and fuzzy c-means (FCM) cluster analysis do not fully utilize the spatial distribution information of geologic samples. In this paper, we propose GEOFCM, a new clustering method for geochemical datasets with location coordinates. A spatial FCM algorithm originally constructed for image segmentation was modified for application to a sparse and unequally-spaced dataset. The proposed algorithm evaluates the membership function of each sample using neighboring samples as a weighting function. To test the proposed algorithm, a synthetic dataset was analyzed by several hyper-parameter settings. Applying this algorithm to a geochemical dataset of granitoids in the Ina-Mikawa district of the Ryoke belt shows that samples collected from the same geological unit are likely to be classified as the same cluster. Moreover, overlapping geochemical trends are classified consistently with spatial distribution, and the result is more robust against noise addition than standard FCM analysis. The proposed method is a powerful tool to use with geological datasets with location coordinates, which are becoming increasingly available, and can help find overviews of complicated multidimensional data structure.

show abstract

Petrology and geochemistry of a calcic and ferrous granitoid pluton: the Mitsuhashi Granite in the Ryoke Belt, southwest Japan.

Cited by 8 publications

References 26 publications

Age gap between the intrusion of gneissose granitoids and regional high‐temperature metamorphism in the Ryoke belt (Mikawa area), central Japan

Age gap between the intrusion of gneissose granitoids and regional high‐temperature metamorphism in the Ryoke belt (Mikawa area), central Japan

Chemical compositions of the late Cretaceous Ryoke granitoids of the Chubu District, central Japan – Revisited

GEOFCM: a new method for statistical classification of geochemical data using spatial contextual information

Contact Info

Product

Resources

About