A sculpture of sandstone outside the Petroleum Museum in Stavanger (Norway) contains some nice examples of deformation bands (Figure 1). These blocks are from the Permian Brumunddal Sandstone which outcrops North of Oslo in the northern part of the Oslo Rift [1, 2]. It is partly aeolian and partly fluvial (2) and theres some nice truncation surfaces in the right hand block. The clear planar crack in the middle and the one running from middle left to bottom right are not natural.
A smaller display in the museum has this sandstone sandwiched in between a shale source rock and a shale seal demonstrating an ideal reservoir rock owing to it's high porosity and permeability. But the blocks (Figure 1) contain deformation bands (particularly pervasive in the left hand block, Figure 2) - which generally form after the sediment was deposited and can drastically reduce the originally high porosity and permeability of reservoir sandstones. This can be beneficial for exploration as they can trap hydrocarbons but generally they are bad news for production, providing baffles to flow. See earlier blog "deformation bands in high porosity sandstones".
The deformation bands in this damage zone have been widened in places by cements (perhaps calcite at label 1 in Figure 2). There are also dark haloes showing further evidence of cementation - these are particularly wide around the deformation bands in left hand side of the block in Figure 2 (label 2). This is where fluids have invaded the host sandstone from one or both sides of each deformation band - a mechanism which is perhaps similar to that described by Edwards et al (1993), [3] in the Permian Hopeman Sandstone in the UK. It is also possible to pick out the relative ages of bands in Figure 2 (label 1). There are also patches of honeycomb weathering (of calcite ?) close to the more pervasive deformation bands (label 3 on Figure 2).
Figure 1. Sculpture of sandstone outside of the Petroleum museum in Stavanger (Norway) containing pervasive network of deformation bands. The blocks are from the Permian Brumunddal Sandstone which outcrops N of Oslo in the Oslo Rift.
Figure 2. Close-up of left hand block in figure 1 showing detail of the damage zone.
RefReferences
[1] Field guide to Permo-Carboniferous sediments around Oslo, Norway,http://folk.uio.no/rtronnes/OsloRift-excursion-articl/OsloRift-IGC08-guide23.pdf
[2] Lothe, A.E, Gabrielsen, R.H,Bjørnevoll Hagen, N, Larsen, B.T. 2002. An experimental study of the texture of deformation bands: effects on the porosity and permeability of sandstones. Petroleum Geoscience, 8, 195 - 207.
[3] Edwards, H.E, Becker, A.D, Howell, J.A. 1993. Compartmentalisation of an aeolian sandstone by structural heterogeneities: Permo-Triassic Hopeman Sandstone, Moray Firth, Scotland. From North, C.P. & Prosser, D.J. (eds), 1993, Characterization of Fluvial & Aeolian Reservoirs. Geological Society Special Publication No 73, 339 - 365.