Figure F28. Compositional variation of coexisting plagioclase, olivine, and augite of Skaergaard (SK) and Hole 735B cumulus phases. A. Anthorite (An) content of plagioclase and forsterite (Fo) content of olivine. B. An content of plagioclase and Mg/(Mg + Fe) ratio of augite. Data for Hole 735B are from Ozawa et al. (1991) and Natland et al. (1991); data from Skaergaard is from Wager and Brown (1967), McBirney (1989), Maaløe (1976), and Nwe (1976). The large open symbols marked (SWIR) designate gabbros dredged along the Southwest Indian Ridge by Meyer et al. (1989) and Bloomer et al. (1989). The observed variation is compared to forward crystal fractionation modeling for potential Skaergaard parental liquids (Wager and Brown, 1987; Brooks and Nielsen, 1990) and representative Atlantis II Fracture Zone basalt glasses as shown in Figure F25. Iron in pyroxenes has been calculated assuming all iron as Fe2+.

Figure F28. Compositional variation of coexisting plagioclase, olivine, and augite of Skaergaard (SK) and Hole 735B cumulus phases. A. Anthorite (An) content of plagioclase and forsterite (Fo) content of olivine. B. An content of plagioclase and Mg/(Mg + Fe) ratio of augite. Data for Hole 735B are from Ozawa et al. (1991) and Natland et al. (1991); data from Skaergaard is from Wager and Brown (1967), McBirney (1989), Maaløe (1976), and Nwe (1976). The large open symbols marked (SWIR) designate gabbros dredged along the Southwest Indian Ridge by Meyer et al. (1989) and Bloomer et al. (1989). The observed variation is compared to forward crystal fractionation modeling for potential Skaergaard parental liquids (Wager and Brown, 1987; Brooks and Nielsen, 1990) and representative Atlantis II Fracture Zone basalt glasses as shown in Figure F25. Iron in pyroxenes has been calculated assuming all iron as Fe²⁺.