Mineral composition of mid-ocean-ridge basalts from ODP Leg 187 sites ...

• Main Author: Sato, Hiroshi
• Format: Article in Journal/Newspaper
• Language: English
• Published: PANGAEA 2004
• Subjects: Drilling/drill rig; Leg187; Joides Resolution; Ocean Drilling Program ODP; Antarc*; Antarctic
• Online Access: https://dx.doi.org/10.1594/pangaea.780714; https://doi.pangaea.de/10.1594/PANGAEA.780714

The chemical compositions of olivine, plagioclase, pyroxene, and spinel in lavas collected during Ocean Drilling Program Leg 187 in the Australian Antarctic Discordance, Southeast Indian Ridge (41°-46°S, 126°-135°E) were analyzed, and modeling of the theoretical equilibrium petrogenetic conditions between olivine and melt was conducted. The cores of larger olivine phenocrysts, particularly in the isotopic Indian-type mid-ocean-ridge basalt (MORB), are not equilibrated with melt compositions and are considered to be xenocrystic. Larger plagioclase phenocrysts with compositionally reversed zonation are also xenocrystic. The compositions of primary magma were calculated using a "maximum olivine fractionation" model for primitive MORB that should fractionate only olivine. Olivine compositions equilibrated with calculated primary magma and compositions of calculated primary magma suggest that (1) isotopic Pacific-type MORB is more fractionated than Indian-type MORB, (2) Pacific-type MORB was produced by higher ... : Supplement to: Sato, Hiroshi (2004): Mineral compositions of MORB from the Australian Antarctic Discordance (AAD): implications for mantle source characteristics. In: Pedersen, RB; Christie, DM; Miller, DJ (eds.) Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 187, 1-26 ...