Surface and subsurface mapping of the Flamborough Head Fault Zone to inform groundwater management in the Yorkshire Wolds, UK.

The Flamborough Head Fault Zone (FHFZ) is a regionally-significant structural zone in northeast England which dissects the Upper Cretaceous Chalk Group, a 500 m thick limestone succession which is a principle aquifer and main source of water supply in the region. The geometry and physical characteristics of the Chalk succession, including the effects of faulting, influence groundwater flow across the region. Consequently, understanding the architecture of the FHFZ is vital to sustainably managing water resources in this area.

The FHFZ marks the southern extent of the Cleveland Basin and the northern margin of the Market Weighton Block and has a complex history of Mesozoic-Cenozoic extension and compression. It is predominantly comprised of east-west trending faults which form a graben that is dissected by north-south trending faults, including the southern extension to the Peak Trough, the Hunmanby Fault. To the west, FHFZ links with the Howardian Fault System and offshore, in the east, it is truncated by the north-south trending Dowsing Fault. The FHFZ is well exposed and described in coastal cliff sections at Flamborough Head but the inland architecture of the faults has hitherto been poorly explored predominantly due to limited inland-exposure.

To address this a multi-faceted approach to geological mapping has been undertaken in the region by the British Geological Survey, in collaboration with the Environment Agency and Yorkshire Water Limited. Remote sensing, targeted field mapping, palaeontological analysis, passive seismic and 2D onshore seismic interpretation have been integrated to understand the inland architecture of the FHFZ in unprecedented detail. Combining these techniques has enabled us to bridge the gap between the surface geology and deeper subsurface structure, increase our understanding of the geology of the region and produce an improved conceptual model at a range of depths which will be used to better manage water resources.