The δ¹³C–δ¹⁸O variations in marble in the Hida Belt, Japan

Abstract

Marble has a great potential to understand a history of various geological events occurring during tectonic processes. In order to decode metamorphic-metasomatic records on C-O isotope compositions of marble at mid-crustal conditions, we conducted a C-O-Sr isotope study on upper amphibolite-facies marbles and a carbonate-silicate rock from the Hida Belt, which was once a part of the crustal basement of the East Asian continental margin. Carbon and oxygen isotope analyses of calcite from marbles (Kamioka area) and a carbonate-silicate rock (Wadagawa area) show a large variation of δ 13 C [VPDB] and δ 18 O [VSMOW] values (from −4.4 to +4.2 ‰ and +1.6 to +20.8 ‰, respectively). The low δ 13 C values of calcites from the carbonate-silicate rock (from −4.4 to −2.9 ‰) can be explained by decarbonation (CO 2 releasing) reactions; carbon-oxygen isotope modeling suggests that a decrease of δ 13 C strongly depends on the amount of silicate reacting with carbonates. The occurrence of metamorphic clinopyroxene in marbles indicates that all samples have been affected by decarbonation reactions. All δ 18 O values of calcites are remarkably lower than the marine-carbonate values. The large δ 18 O variation can be explained by the isotope exchange via interactions between marble, external fluids, and/or silicates. Remarkably low δ 18 O values of marbles that are lower than mantle value (+5 ‰) suggest the interaction with meteoric water at a later stage. Sr isotope ratios ( 87 Sr/ 86 Sr = 0.707255-0.708220) might be close to their protolith values.One zircon associated with wollastonite in a marble thin-section yields a U-Pb age of 222 ± 3 Ma, which represents the timing of the recrystallization of marble, triggered by H 2 O-rich fluid infiltration at a relatively high-temperature condition. Our isotope study implies that the upper amphibolite-facies condition, like the Hida Belt, might be appropriate to cause decarbonation reactions which can modify original isotope compositions of marble if carbonates react with silicates.

LateTriassic A‐type granite boulders in Lower Cretaceous conglomerate of theHida belt, Japan: Their origin and bearing on theYamatotectonic line inFar East Asia

“…In this context, a correlative 225.8 ± 3.9 Ma U–Pb age reported from a zircon rim in the “Inishi migmatite” in the Hida belt (Sakoda et al, 2006) is noteworthy. Another U–Pb age of 225.4 ± 1.9 Ma was lately added also from titanite in a migmatitic leucogranite (Harada, Tsujimori, Kon, et al, 2021; Harada, Tsujimori, Kunugiza, et al, 2021). These ages are distinct from the representative two main age clusters at ca.…”

“…This age combination of granitoids has been never detected in the rest of Japan, except for a small domain in SW Japan along the Japan Sea coast (Tsutsumi et al, 2017). The protoliths of the gneissose rocks are also unique in possessing impure marble and calc‐silicate rocks (Harada, Tsujimori, Kon, et al, 2021; Harada, Tsujimori, Kunugiza, et al, 2021; Isozaki, 1997; Kano, 1998; Suwa, 1990), which are different from other gneissose rocks in Japan. In addition, a thick mid‐Jurassic to Lower Cretaceous shallow marine/non‐marine strata of terrigenous clastic facies, traditionally called the Tetori Group as a whole, which unconformably rest upon the above‐mentioned basement granitoids/gneisses (e.g., Oishi, 1933; Maeda, 1961; Omura, 1974; Figure 1b).…”

Geochronology and geochemistry of early Palaeozoic ultramafic rocks along Jiangshan‐Shaoxing Fault and their tectonic significance

“…Simplified tectonic map of East Asia (a) (modified after Harada et al, 2021); Simplified geological map of early Paleozoic igneous rocks in the SCB (b) (modified after Shu et al, 2020). The ultramafic‐mafic rocks are not drawn to scale and shown as circles with serial number.…”

Cretaceous to Miocene NW Pacific Plate Kinematic Constraints: Paleomagnetism and Ar–Ar Geochronology in the Mineoka Ophiolite Mélange (Japan)

“… (a) Tectonic map of oceanic plates in the East Asia and location of the Mineoka Ophiolite Mélange (modified from Harada et al., 2021; Ishiwatari et al., 2016; Tsujimori & Liou, 2005). AP‐ Amami Plateau; DR‐ Daito Ridge; ODR‐ Oki Daito Ridge; UR‐ Urdaneta Ridge; BR‐Benham Rise; KPR‐ Kyushu‐Palau Ridge.…”

“…GANBAT ET AL. Harada et al, 2021;Ishiwatari et al, 2016;Tsujimori & Liou, 2005). AP-Amami Plateau; DR-Daito Ridge; ODR-Oki Daito Ridge; UR-Urdaneta Ridge; BR-Benham Rise; KPR-Kyushu-Palau Ridge.…”