Fault striae, Oslo, Norway - Interpreted

The fault striae are relatively easily seen here. Some other subtle aspects evident here are small bands or striping within the lighter colored patches of linear calcite growth. These are small microveins with the calcite growths. Also, breakage has occurred so that small steps between fault slip surfaces occur. Here they are preferentially on the lower end, and this helps indicate that that sense of motion was that the overlying block (now eroded away) moved down relative to the underlying fault block. Since the striae run approximately down the dip of the fault surface, this then would be a normal fault. Likely this fault moved slowly and did not produce earthquakes (at least during the time of movement that formed the slickensides.

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