Abstract
Seven occurrences of sapphirine-bearing rocks in the Fiskenæsset region are described in detail. They occur within a chromite-layered anorthosite complex that was metamorphosed by a hornblende-granulite facies metamorphism and then by a cordierite-amphibolite facies metamorphism. They were derived from spinel-layered ultramafic rocks that mostly occur as layers and lenses along the contacts between major metaanorthosite and pyribolite/amphibolite horizons within the complex. There are four types of sapphirine-bearing rocks - enstatite, pargasite, gedrite and phlogopite types, which represent a petrogenetic sequence involving increasing degrees of Si, Ca, K and H2O metasomatism related to shearing and deformation along meta-anorthosite-pyribolite junctions. Their relationship to associated non-sapphirine-bearing rocks is described. Brief mineralogical and petrological data are given for the principal minerals and rocks. In addition, two occurrences in the Sukkertoppen region are described in detail; these are also localised in meta-norite-ultramafic lenses in high grade gneisses. It is concluded that sapphirine is stable within a wide range af pressure and temperature conditions, but within a limited range of chemical environments.
Highlights
Sapphirine has been known to occur in West Greenland for about a hundred and fifty years and it is clear that this is one of the principal areas of its occurrence in the world
The present paper describes the various types of sapphirinebearing rocks of West Greenland in relationship to their geological setting, demonstrates the common factors in their occurrence and outlines the principal metamorphic and chemical conditions responsible for the formation of sapphirine and its associated minerals in this particular environment
A 40 cm sw o wide pargasite-cordierite-rich layer at the northern contact with the pyribolite contains abundant pink corundum crystals up to 10 cm long and 1.5 cm across. This rock contains patches up to 2 cm across very rich in sapphirine' an account of the considerable extent and width of the main phlogopite type layer, there is clearly more sapphirine at this locality than any other yet found in West Greenland
Summary
Sapphirine has been known to occur in West Greenland for about a hundred and fifty years and it is clear that this is one of the principal areas of its occurrence in the world. It was realised that all these sapphirine localities occurred within a metamorphosed chromite-layered anorthosite-pyribolite-ultramafic complex (Ghisler and Windley, 1967), termed the Fiskenæsset complex (Windley, in press, a). The present paper describes the various types of sapphirinebearing rocks of West Greenland in relationship to their geological setting, demonstrates the common factors in their occurrence and outlines the principal metamorphic and chemical conditions responsible for the formation of sapphirine and its associated minerals in this particular environment. The retrogressive metamorphism in the eastern Fiskefjord and southern Fiskenæsset regions is believed to have taken place about 2600 m.y. ago (Windley, in press, b) It is in this environment that the sapphirine-bearing rocks occur; they are situated in the anorthositic-noritic rocks that have been doubly metamorphosed.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
