New evidence concerning the original relationships of early Precambrian volcanics and anorthosites in the Fiskenæsset region, southern West Greenland

Abstract

With detailed mapping of the Fiskenæsset region nearing completion, the authors started coordination and synthesis of the geology of the region as a whole, in the fieId, during the summer. The main lithologies of the region are quartzo-feldspathic gneisses, gneissose granites, amphibolites and anorthosite, with minor amounts of ultramafic rocks and metasediments. Their relationships, composition and structure have been summarised by Kalsbeek & Myers (1973). Most of the quartzo-feldspathic gneisses appear to be derived from acid and intermediate intrusions into the older amphibolite and anorthosite units (Myers, in press). These gneisses were themselves deformed and then cut by thick sheets of porphyritic granite, Ilivertalik granite, in the north of the region.