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. The Hareelv Formation of the Jameson Land Basin (East Greenland) provides one of the best outcrop examples of a large-scale (>4000 km²) injectite complex within an extensional tectonic setting. We used 3D photogrammetric models and field observations to characterize the large-scale geometries of the Hareelv Formation injectite sand bodies and propose a new model for closed system injectite complexes. 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, nor candidate parent units, is present. The Hareelv Formation injectites are therefore 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 the identification of source units is uncertain.