The tholeiitic and komatiitic affinities of the Malene metavolcanic amphibolites from Ivisârtoq, southern West Greenland

Abstract

The chemistry of a suite of representative samples of the various Malene amphibolite Iithologies from Ivisârtoq has been analysed by X-ray fluorescence (XRF) techniques. The major element chemistry of the amphibolites is very variable and is compared to that of amphibolites from other Archaean terrains and to modem basaltic lavas. Pillow-structured and intercalated homogeneous horizons prevail among the amphibolites of Ivisârtoq. These predominant units comprise a suite which ranges chernically from abyssal tholeiite through to basaItic and pyroxenitic komatiite in character, and chromium and nickel contents are in accordance with this classification. The well preserved pillow structures indicate that these rocks originated as subaqueous basic and ultrabasic lavas, and include the first reported ultramafic pillows in the Archaean of southern West Greenland.