1 Department of Earth Sciences, Faculty of Science, Aarhus University, Aarhus University2 Department of Geoscience, Science and Technology, Aarhus University3 DONG Energy4 Department of Geological Mapping, Geological Survey of Denmark and Greenland5 Department of Geoscience, Science and Technology, Aarhus University
Postdepositional remoblization and injection of sand are important processes in deep-water clastic systems. Subsurface mobilisation and injection of sand has been recently recognised as a significant control of deep-water sandstone geometry. Kilometre-scale injection complexes have been interpreted in the Paleocene Siri Canyon near the Danish Central Graben of the North Sea hydrocarbon province from borehole data. The emplacement of large-scale injection complexes has been commonly attributed in the geological literature to seismic activity and consequent sand liquefaction. However, due to very small differences in textural and compositional properties, and the lack of depositional structures of reservoir sands in the Siri Canyon, the distinction between "in situ" and injected or remobilised sands is difficult. Large scale heavy mineral sorting (in 10 m thick units) is observed in several reservoir units and has been interpreted to represent the depositional sorting. This study demonstrates the detailed sorting pattern of heavy minerals in thin, injected sands and relates it to the flow patterns during injection. The sorting pattern is used to explain the large scale sorting pattern of the reservoir sands and to suggest a tool for petrographic/geochemical distinction between "in situ" sands and their related injected sands within a submarine canyon setting.