Paul Dennis edited geology2.tex  over 8 years ago

Commit id: eff81e5ecfea0d8603ac37171d165988d10b19da

deletions | additions      

       

The seismic profile and section shown in Figure 2 is taken across the north margin of the platform. The lack of internal deformation in the Edale Basin sediments is evident in the section and the present basin topography is essentially unchanged from the end of the Visean. Whilst there is no extant thermal modelling of the Edale Basin recent work has been done on the Widmerpool Gulf to the south of the Derbyshire Platform. This is part of ongoing assessment of the shale gas resource potential of the Bowland-Hodder unit. For the Widmerpool Gulf a maximum burial depth of 3.6km for the base of the Bowland-Hodder shale unit is estimated to have been reached at the Carboniferous-Permian boundary. A high modelled heat flow in excess of 70$\mu$W.m^{-2} 70$\mu$W.m$^{-2}$  resulted in a geothermal gradient of close to 50$^{\circ}$.km^{-1}. Maximum temperatures at the base of the basin are inferred to be close to 200$^{\circ}$C (Anderson, 2013). Available vitrinite reflectance (VR) data suggest somewhat lower maximum temperatures of between 110 and 140$^{\circ}$C (Anderson, 2013) The maximum burial depth for the platform is somewhere between 1 and 2km with lower maximum temperatures. Apatite fission track analysis and VR data for shales from the upper Carboniferous on the platform suggests maximum temperatures of 60-70$^{\circ}$C (Green, 2005).