Remnants of Mesoarchaean oceanic crust in the Tartoq Group, South-West Greenland

Abstract

The Tartoq Group is located in the Sermiligaarsuk fjord region in South-West Greenland in an area of approximately 20 × 50 km (Fig. 1). The Tartoq Group consists of several discrete, fault-bound blocks of metavolcanic rocks, surrounded by Archaean tonalite-trondhjemite-granodioritetype (TTG) gneisses. A zircon age of 2996.3 ± 5.9 Ma of a TTG intrusion provides a minimum age for the formation of the Tartoq Group (Fig. 2). The metavolcanic rocks probably show the lowest degree of metamorphism found anywhere in the Archaean craton of Greenland. Here we present a new model for the origin of the metavolcanic rocks of the Tartoq Group based on geochemical, metamorphic and structural data. The samples used for this study were collected by the Geological Survey of Denmark and Greenland (GEUS) in 2009 and 2010. The study is part of a joint project between the Greenland Bureau of Minerals and Petroleum and GEUS on the mineral potential of south-western Greenland.