Hydrothermally influenced cementation of sandstone — An example from deeply buried Cambrian sandstones from Bornholm, Denmark

Cambrian sandstones on Bornholm (Denmark) are tightly cemented by quartz. Cementation occurred after deep burial as evidenced by a very strong compaction, partly mediated by intensive grain fracturing. The quartz cement has a complex cathodoluminescence (SEM-CL)-zonation which is related to variable substitution of Al in the quartz lattice. Based on the substitution pattern and SEM-CL-zonation, three phases of quartz growth can be identified. Phase 1 cement has a low SEM-CL-level and its volume corresponds approximately to the estimated volume of press-solved detrital quartz. It is related to the late compaction. Phase-2 cement is the volumetrically most important. It has an intricate SEM-CL-zonation and associated Al-substitution. It is referred to hydrothermal activity related to the Permo–Carboniferous magmatic and tectonic event. The cementation gradually reduced the influence of hydrothermal flow, and late Phase-3 cement has a low-intensity and more simple SEM-CL-pattern. The almost fully cemented sandstone was fractured and the fractures were filled by hydrothermal chlorite, sulphides and quartz. These minerals are also found sporadically as cement in the sandstones.