Giant Injectite Complex Sand Body Architecture in the Late Jurassic East Greenland Rift

The geometries of kilometre-scale sandstone injectite complexes, and the models developed for their emplacement, are based on a scarce dataset of Large Sandstone Intrusion Complexes (LSICs). The Hareelv Formation of the Jameson Land Basin (East Greenland) provides the best outcrop example of a large-scale (>4,000 km 2 ) injectite complex within an extensional tectonic setting found globally. Using 3D photogrammetric models and field observations, the large-scale geometries of the Hareelv Formation injectite sand bodies are characterised, and a new model for closed system injectite complexes is proposed. The Hareelv Formation sand bodies are up to 50 m thick and 1-2 km wide. Common features include steps, low-angle discordant wings, host rock rafts, bifurcations, linking-complexes and stockworks. No physical evidence for linkage to the palaeoseabed, or candidate parent units. is present. Therefore, the Hareelv Formation injectites are inferred to have acted as a closed system: self-sourced and dominated by lateral injection. The distribution of the sealing organic rich, laminated host mudstones exerts a primary control on the development of injectites in the Jameson Land Basin and adjacent regions. The self-sourced lateral intrusion processes may provide a more appropriate mechanism for the interpretation of subsurface examples where identification of source units has been uncertain.