Experimental study of a low-alkali tholeiite at 1–5 kbar: optimal condition for the crystallization of high-An plagioclase in hydrous arc tholeiite

Takagi, Daisuke; Sato, H.; Nakagawa, Mitsuhiro

doi:10.1007/s00410-005-0666-7

Cited by 135 publications

(75 citation statements)

References 37 publications

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“…In natural basaltic rocks, orthopyroxene and magnetite are commonly observed in addition to olivine, plagioclase and clinopyroxene. Accuracy in recovering temperature for the melt saturated with olivine + plagioclase + clinopyroxene ± orthopyroxene ± magnetite is also assessed using the corresponding experimental results from the literature (Kinzler and Grove, 1992;Gaetani et al, 1994;Takagi et al, 2005;Hamada, 2006) ( Fig. 8(b)).…”

Section: Overgrowth Correction Of Plagioclase-hosted Melt Inclusions mentioning

confidence: 99%

“…Data sources of experiments with 0-9 wt.% H 2 O in melt: Rutherford et al (1985), Baker and Eggler (1987), Housh and Luhr (1991), Kinzler and Grove (1992), Grove (1993a, 1993b), and Takagi et al (2005).…”

Section: Fig A2 Correspondence Between the Logarithm Of Division Ofmentioning

confidence: 99%

“…Carich plagioclase (mostly An ≥90 ), commonly found in island arc basalt at the volcanic front, is often more Carich than those found in MORB. This difference would be attributed to higher H 2 O content in island arc basalt than MORB because experimental studies have shown that H 2 O in melt increases K D(Ca-Na) plag-melt (e.g., Sisson and Grove, 1993a;Takagi et al, 2005;Feig et al, 2006). Indeed, reported H 2 O content of plagioclase-hosted basal-438 M. Hamada and T. Fujii accumulation of plagioclase in the upper parts of magma chambers beneath the Izu-Oshima volcano, which required less than 0.7 wt.% H 2 O to float plagioclase in melt.…”

Section: Introductionmentioning

confidence: 99%

“…An identical calculation at P = 0.05 GPa (<0.3 GPa) yielded similar results. Decreasing pressure is not significant to the origin of Ca-rich plagioclase, although such decrease in pressure increases K D(Ca-Na) plag-melt by ~50% (Takagi et al, 2005). Complete failure in reproducing the original K D(Ca-Na) plag-melt suggests that the analyzed H 2 O content does not represent H 2 O content at the time of crystallization and entrapment, and therefore, overgrowth correction was applied assuming greater H 2 O in melt inclusions.…”

mentioning

confidence: 99%

“…Takagi et al (2005) claimed that optimal H 2 O content for crystallization of Ca-rich plagioclase from island arc tholeiite magma is ~5 wt.%. However, quantitative discussions on H 2 O content of island arc basalt at the volcanic front have not reached consensus to date.…”

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confidence: 99%

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H2O-rich island arc low-K tholeiite magma inferred from Ca-rich plagioclase-melt inclusion equilibria

Hamada

Fujii

2007

Geochem. J.

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In order to quantify H 2 O content and chemical composition of island arc low-K tholeiite magma that crystallized Carich plagioclase, melt inclusions of a typical island arc tholeiite from Izu-Oshima volcano (34°N 44′, 139°E 24′) were analyzed. Composition of studied plagioclase ranges widely from An 83 to An 95 . Composition of studied melt inclusions also shows wide variation, which suggests that the melt inclusions represent various stages of crystallization differentiation at Izu-Oshima volcano. Ca/Na ratios of plagioclase-hosted melt inclusions are comparable with compositions of aphyric lava, which preclude an exotic origin for the Ca-rich plagioclase. Analyzed H 2 O content of the melt inclusions ranges from 0.2 to 2.4 wt.% (0.2 to 1.4 wt.% for plagioclase-hosted melt inclusions and 0.8 to 2.4 wt.% for olivine-hosted melt inclusions).Ca/Na partition coefficient between plagioclase and hydrous basaltic melt, K D(Ca-Na) plag-melt , is empirically calibrated based on experimental data as Based on the equilibria between host plagioclase and melt inclusion and taking effect of overgrowth into consideration, 3 to 6 wt.% H 2 O in melt is required. The lower H 2 O content of the analyzed melt inclusions is probably due to the leakage of volatiles through the host crystal during decompression, eruption and quench. Variation in estimated H 2 O content in the melt at the time of crystallization of plagioclase (3 to 6 wt.%) can be due to polybaric crystallization from H 2 O-saturated melt.Keywords: melt inclusion, Ca-rich plagioclase, island arc low-K tholeiite magma, H 2 O content in melt, hydrous melting experiment tic melt inclusions from the subaqueous Izu arc front ranges from 1 to 5 wt.% (Straub and Layne, 2003). Takagi et al. (2005) claimed that optimal H 2 O content for crystallization of Ca-rich plagioclase from island arc tholeiite magma is ~5 wt.%. However, quantitative discussions on H 2 O content of island arc basalt at the volcanic front have not reached consensus to date. Sakuyama (1979) proposed lateral variation of H 2 O content in northeast Japan arc based on the crystallization sequence and temperature, which lead to the conclusion that the H 2 O content of island arc basalt at the volcanic front was small. Aoki et al. (1981) also proposed similar lateral variations of H 2 O content based on fluorine geochemistry assuming constant proportions of K 2 O:H 2 O:F during fractional crystallization. The 1986 eruption of Izu-Oshima volcano (34°N 44′, 139°E 24′), which is a typical frontal arc volcano and issues island arc low-K tholeiite magma, stimulated the discussion on H 2 O content in island arc basalt. Aramaki and Fujii (1988) calculated the H 2 O content of basaltic melt to explain the INTRODUCTIONQuantifying the H 2 O content of island arc basalt at the volcanic front, especially island arc low-K tholeiite magma, is fundamental in understanding the generation and differentiation of magma at island arc settings. Carich plagioclase (mostly An ≥90 ), commonly found in island arc basalt at the volcan...

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Section: Overgrowth Correction Of Plagioclase-hosted Melt Inclusions mentioning

confidence: 99%