Morphology and composition of spinel in Pu’u ’O’o lava (1996–1998), Kilauea volcano, Hawaii

Roeder, P. L.; Thornber, Carl R.; Poustovetov, Alexei; Grant, Alan H.

doi:10.1016/s0377-0273(02)00508-5

Cited by 32 publications

(4 citation statements)

References 30 publications

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“…Ozawa ; Agata ; Roeder et al . ). We think that the somewhat different trend may be the result of rather high compositional modification by diffusion‐controlled crystallization.…”

Section: Discussionmentioning

confidence: 97%

“…Similar Al‐ and Mg‐decreasing trends have been reported in other MORBs (Fisk & Bence ; Roeder et al . ), and experimental results have shown that chrome spinel from MORB increases its Cr/(Cr+Al) ratio with fractionation after plagioclase begins to crystallize (Roeder & Reynolds ).…”

Section: Discussionmentioning

confidence: 99%

“…The kinetic effects that result in zoning include diffusion‐controlled rapid growth of spinel from super‐cooled magma (Roeder et al . , ). The East Takayama chrome spinel occasionally contains negative crystal‐shaped glass inclusions, which are indicative of rapid crystallization; the kinetic effects may have caused the core‐to‐rim compositional variation.…”

Section: Discussionmentioning

confidence: 99%

“…), and kinetic processes including cooling rate of magma (Roeder et al . ). Spinel composition, therefore, cannot be correlated sufficiently with the stages of spinel crystallization, and the crystallization course of chrome spinel in MORB remains poorly understood.…”

Section: Introductionmentioning

confidence: 97%

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Chrome spinel in normal MORB‐type greenstones from the Paleozoic–Mesozoic Mino terrane, East Takayama area, central Japan: Crystallization course with a U‐turn

Agata

Adachi

2014

Island Arc

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Phenocrystic chrome spinel crystallized in normal MORB‐type greenstones in the East Takayama area. Associated phenocryst minerals show a crystallization sequence that was olivine first, followed by plagioclase, and finally clinopyroxene. Chrome spinel ranges from 0.54 to 0.77 in Mg/(Mg+Fe2+) and 0.21 to 0.53 in Cr/(Cr+Al); the Fe3+ content varies from 0.07 to 0.22 p.f.u. (O = 4). Significant compositional differences of spinel were observed among the phenocryst mineral assemblages. Chrome spinel in the olivine–spinel assemblage shows a wide range in Cr/(Cr+Al), and is depleted in Fe2+ and Fe3+. Chrome spinel in the olivine–plagioclase–clinopyroxene–spinel assemblage is Fe2+‐ and Fe3+‐rich at relatively high Cr/(Cr+Al) ratios. Basalt with the olivine–plagioclase–spinel assemblage contains both aluminous spinel and Fe2+‐ and Fe3+‐rich spinel. The assumed olivine–spinel equilibrium suggests that chrome spinel in the olivine–spinel assemblage changed in composition from Cr‐ and Fe2+‐rich to Al‐ and Mg‐rich with the progress of fractional crystallization. Chrome spinel in the olivine–plagioclase–clinopyroxene–spinel assemblage, on the other hand, exhibits the reversed variations in Mg/(Mg+Fe2+) and in Cr/(Cr+Al) ratios that decrease and increase with the fractional crystallization, respectively. The entire crystallization course of chrome spinel, projected onto the Mg/(Mg+Fe2+)–Cr/(Cr+Al) diagram, exhibits a U‐turn, and appears to be set on a double‐lane route. The U‐turn point lies in the compositional field of chrome spinel in the olivine–plagioclase–spinel assemblage, and may be explained by plagioclase fractionation that began during the formation of the olivine–plagioclase–spinel assemblage.

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“…Ozawa ; Agata ; Roeder et al . ). We think that the somewhat different trend may be the result of rather high compositional modification by diffusion‐controlled crystallization.…”

Section: Discussionmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

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