The East Greenland flood basalt province covers an area of 65,000 km2 with lava sequences >6 km thick approaching the coast (Pedersen et al., 1997) (Fig. F1). High-resolution chemical stratigraphy of the flood basalts has shown that the succession can be divided into two series (Fig. F5). A basal volcanic series is composed of heterogeneous and laterally discontinuous successions of picritic and tholeiitic lavas and pyroclastic rocks. This lower volcanic series is exposed principally in the southwestern portion of the province (Soper et al., 1976; Nielsen et al., 1981; Holm, 1988; Fram and Lesher, 1997) and includes the most primitive lavas found. These lavas record a complex high-pressure fractionation history and are frequently modified by crustal contamination (e.g., Fram and Lesher, 1997; Hansen and Nielsen, 1999). Eruption of the lower volcanics was associated with active faulting within the Cretaceous basin into which they were erupted (Nielsen et al., 1981; Ukstins et al., 2003).
The overlying main series of flood basalt volcanism is divided into four mappable formations erupted between 56 and 54 Ma: (1) Milne Land Formation, Geikie Plateau Formation, Rømer Fjord Formation, and Skrænterne Formation (Larsen et al., 1989; Pedersen et al., 1997). The main series is dominated by evolved tholeiites, with subordinate volumes of olivine tholeiite and occasional picrite flows in the lower portions of the succession. Two distinct suites of tholeiites are distinguished; a high-Ti suite that represents >90% of the succession and a low-Ti suite that closely resembles ocean-ridge basalt. Lavas of these two suites are interbedded in the succession and are interpreted by Tegner et al. (1998b) to reflect eruptive activity either from vents within continental crust along the rifted margin or from a nascent spreading system formed within highly attenuated crust to the east. Interestingly, lavas typical of the high-Ti suite of East Greenland are not reported from successions drilled along the 63°N transect but are common from the Paleogene exposures on Iceland.