Open AccessChromium-rich sapphirine from the Bjørnesund area, southern West Greenland and its bearing on the conditions of crystallisation of the Fiskenæsset anorthosite complex
Author(s) -
C. R. L. Friend,
David J. Hughes
Publication year - 1981
Publication title -
rapport
Language(s) - English
Resource type - Journals
eISSN - 2597-2944
pISSN - 0418-6559
DOI - 10.34194/rapggu.v105.7751
Subject(s) - anorthosite , chromite , geochemistry , geology , layered intrusion , pyroxene , chromium , precipitation , intrusion , chemistry , plagioclase , olivine , geography , paleontology , quartz , organic chemistry , meteorology
Windley et al. (1973) have postulated that the Fiskenæsset anorthosite complex crystalIised under conditions of high water vapour pressure. This hypothesis readily explains several of the distinct characteristics of the complex. In particular, the late precipitation of chromitite layers towards the top of the complex in the anorthosite sensu stricto (Ghisler & Windley, 1967) is not normally expected in large layered intrusions (Wager & Brown, 1968), and is explained because the early precipitation of chromite is suppressed under such conditions (Shiraki, 1966). AIso, Windley et al. (1973) have suggested that chromium amphibole, rather than pyroxene, was precipitated in association with the chromite as a direct consequence of the enrichment of volatiles in the upper parts of the intrusion.