Petrological study of granitic rocks from the Kashiwajima-Okinoshima district in the southwestern part of Kochi Prefecture.

Dai, Kaishu; Tsusue, Akio; Honma, Hiroaki

doi:10.2465/ganko.88.247

Cited by 8 publications

(9 citation statements)

References 19 publications

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“…These compositional relationships of the TSUG are comparable to those of other Middle Miocene granites of Southwest Japan (e.g. Aramaki et al , 1972;Nakada, 1983;Okamoto et al , 1987;Tsusue et al , 1987;Dai et al , 1993;Shinjoe, 1997;Anma et al , 1998 ). The leucocratic and gray granites fall into the subalkaline fi eld on an (Na 2 O + K 2 O)/ SiO 2 -SiO 2 diagram and the calc-alkaline fi eld on a FeO T / MgO-SiO 2 diagram, respectively ( Fig.…”

Section: Major-and Trace-element Compositions Of Whole Rockssupporting

confidence: 77%

“… Harker’s variation diagrams for the Tsushima granites. The shaded area represents major element composition of the Outer Zone granites (Tateishi et al , 1986; Terakado et al , 1988; Yamamoto et al , 1988; Dai et al , 1993; Yoshida et al , 1993; Shinjoe, 1997; Anma et al , 1998; Shinjoe et al , 2007). (a) Fe 2 O 3 T , r 2 = 0.98; (b) TiO 2 , r 2 = 0.95; (c) CaO, r 2 = 0.94; (d) MgO, r 2 = 0.95; (e) Al 2 O 3 , r 2 = 0.89; (f) MnO, r 2 = 0.81; (g) P 2 O 5 , r 2 = 0.80; (h) K 2 O, r 2 = 0.70; (i) Na 2 O, r 2 = 0.43.…”

Section: Resultsmentioning

confidence: 99%

“… Trace‐element variation diagrams for the Tsushima granites. The shaded area represents trace element composition of the Outer Zone granites (Terakado et al , 1988; Dai et al , 1993; Yoshida et al , 1993; Shinjoe, 1997; Anma et al , 1998; Shinjoe et al , 2007). (a) Ba; (b) Th; (c) Pb; (d) Rb; (e) Sc; (f) Nd; (g) Sr; (h) Zr; (i) Yb; (j) Rb/Sr; (k) (La/Yb) N .…”

Section: Resultsmentioning

confidence: 99%

“…REE concentrations of the gray granites had a wide variation: one end-member was characterized by an REE-depleted pattern with a positive Eu Harker's variation diagrams for the Tsushima granites. The shaded area represents major element composition of the Outer Zone granites ( Tateishi et al , 1986;Terakado et al , 1988;Yamamoto et al , 1988;Dai et al , 1993;Yoshida et al , 1993;Shinjoe, 1997;Anma et al , 1998;Shinjoe et al , 2007 ). ( Terakado et al , 1988;Dai et al , 1993;Yoshida et al , 1993;Shinjoe, 1997;Anma et al , 1998;Shinjoe et al , 2007 ).…”

Section: Major-and Trace-element Compositions Of Whole Rocksmentioning

confidence: 99%

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Genesis and Mixing/Mingling of Mafic and Felsic Magmas of Back‐Arc Granite: Miocene Tsushima Pluton, Southwest Japan

et al. 2009

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The Middle Miocene Tsushima granite pluton is composed of leucocratic granites, gray granites and numerous mafi c microgranular enclaves (MME). The granites have a metaluminous to slightly peraluminous composition and belong to the calc-alkaline series, as do many other coeval granites of southwestern Japan, all of which formed in relation to the opening of the Sea of Japan. The Tsushima granites are unique in that they occur in the back-arc area of the innermost Inner Zone of Southwest Japan, contain numerous miarolitic cavities, and show shallow crystallization (2 -6 km deep), based on hornblende geobarometry. The leucocratic granite has higher initial 87 Sr/ 86 Sr ratios (0.7065 -0.7085) and lower Nd(t) (−7.70 to −4.35) than the MME of basaltic -dacitic composition (0.7044 -0.7061 and −0.53 to −5.24), whereas most gray granites have intermediate chemical and Sr -Nd isotopic compositions (0.7061 -0.7072 and −3.75 to −6.17). Field, petrological, and geochemical data demonstrate that the Tsushima granites formed by the mingling and mixing of mafi c and felsic magmas. The Sr -Nd -Pb isotope data strongly suggest that the mafi c magma was derived from two mantle components with depleted mantle material and enriched mantle I (EMI) compositions, whereas the felsic magma formed by mixing of upper mantle magma of EMI composition with metabasic rocks in the overlying lower crust. Element data points deviating from the simple mixing line of the two magmas may indicate fractional crystallization of the felsic magma or chemical modifi cation by hydrothermal fl uid. The miarolitic cavities and enrichment of alkali elements in the MME suggest rapid cooling of the mingled magma accompanied by elemental transport by hydrothermal fl uid. The inferred genesis of this magma -fl uid system is as follows: (i) the mafi c and felsic magmas were generated in the mantle and lower crust, respectively, by a large heat supply and pressure decrease under back-arc conditions induced by mantle upwelling and crustal thinning; (ii) they mingled and crystallized rapidly at shallow depths in the upper crust without interaction during the ascent of the magmas from the middle to the upper crust, which (iii) led to fl uid generation in the shallow crust. The upper mantle in southwest Japan thus has an EMI-like composition, which plays an important role in the genesis of igneous rocks there.

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Section: Major-and Trace-element Compositions Of Whole Rockssupporting

confidence: 77%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Major-and Trace-element Compositions Of Whole Rocksmentioning

confidence: 99%

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Genesis and Mixing/Mingling of Mafic and Felsic Magmas of Back‐Arc Granite: Miocene Tsushima Pluton, Southwest Japan

et al. 2009

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“…At the beginning of studies on ages of the Outer Zone Granites, however, an age of each granite was estimated using data from one locality without investigation of its cooling history (Shibata and Nozawa, 1967). Recent researches (e.g., Murakami et al, 1989;Iwaya and Mimura, 1992;Dai et al, 1993;Hasebe et al, 1993;Tagami and Shimada, 1996;Sumii et al, 1998) re-estimate their emplacement ages carefully, still supporting the contemporaneity of the Outer Zone Granite intrusion.…”

mentioning

confidence: 99%

Fission track ages of the Omine Acidic Rocks, Kii Peninsula, Southwest Japan.

Hasebe

Suwargadi

Nishimura³

2000

Geochem. J.

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Fission track (FT) ages of the Omine Acidic Rocks, one of the Tertiary granitic rocks which occurs in the Outer Zone of the Median Tectonic Line, Southwest Japan, are determined in order to assess the timing of intrusion. Nine FT zircon (ZR) ages and one apatite (AP) age are obtained for igneous rocks, and four ZR ages for basement sandstone. Data for each pluton are concordant within a body representing the time of intrusion. The ZR ages from sandstone are concordant with the nearest pluton. The ages of plutons are classified into two groups statistically, suggesting that the Omine Acidic Rocks formed by two intrusive events. The Dorogawa, Tenguyama, Shiratani and Katago-Mukuro Dike are the older group with the weighted mean age of 16.8 ± 0.8 Ma, and the Kose pluton are the younger with an age of 14.2 ± 1.7 Ma. magma intrusion and tectonic framework at the time. Because of their possible complicated histories, the emplacement ages of granites should be estimated after investigation of their cooling histories by means of an age mapping and a combination of several dating techniques. At the beginning of studies on ages of the Outer Zone Granites, however, an age of each granite was estimated using data from one locality without investigation of its cooling history (Shibata and Nozawa, 1967).

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Provenance of granitic gravestones in graveyard of feudal lords evaluated by multiple non-destructive rock analyses

Tanikawa

Tokuyama²,

Mochizuki³

et al. 2022

Journal of Cultural Heritage

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Petrological study of granitic rocks from the Kashiwajima-Okinoshima district in the southwestern part of Kochi Prefecture.

Cited by 8 publications

References 19 publications

Genesis and Mixing/Mingling of Mafic and Felsic Magmas of Back‐Arc Granite: Miocene Tsushima Pluton, Southwest Japan

Genesis and Mixing/Mingling of Mafic and Felsic Magmas of Back‐Arc Granite: Miocene Tsushima Pluton, Southwest Japan

Fission track ages of the Omine Acidic Rocks, Kii Peninsula, Southwest Japan.

Provenance of granitic gravestones in graveyard of feudal lords evaluated by multiple non-destructive rock analyses

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