BGS Karst Report Series: P1. Karst in the northern outcrop of Permian limestones

Maurice, L.D.; Cooper, A.H.; Farrant, A.R.; Mathewson, E.; Murphy, P.J.. 2024 BGS Karst Report Series: P1. Karst in the northern outcrop of Permian limestones. Nottingham, UK, British Geological Survey, 61pp. (OR/23/036) (Unpublished)

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Abstract/Summary

This report documents the evidence for karst and rapid groundwater flow in the northern outcrop of the Permian dolomitic limestones and their associated gypsum sequences in County Durham and a small part of North Yorkshire, in northern England. It is part of the BGS karst report series on those karst aquifers in England in which cave development is limited – principally the Upper Cretaceous Chalk and the Jurassic and Permian limestones. The term “karst” applies to rocks that are soluble. In classic karst there are extensive caves and large-scale surface karst landforms such as dolines, shafts, stream/river sinks, and springs. In the past, the Chalk and the Jurassic and Permian limestones of England were not considered karstic because they have limited cave development, and because karst features are usually small and have not been well documented. The reports provide data and information on karst in each area. There is clear evidence for karstic development in the Permian dolomitic limestones in the P1 area. Some short caves occur which appear to be fully or partially karstic in origin, and although they are now predominantly dry, they demonstrate that cave sized voids can develop in the limestones. Other caves and voids related to mass-movement are also present. There are also smaller karstic conduits, solutional fissures, dolines, dissolution pipes, stream sinks and springs present. However, there are no comprehensive datasets on these features and information on their frequency, distributions and characteristics is generally scarce. There is some further evidence that karstic networks of solutional fissures and conduits occur in the saturated zone, with some high transmissivities and yields, and large fissure inflows during construction. Both the unsaturated and saturated zones of the aquifer are impacted by karst, with a proportion of rapid recharge via surface karst features and solutional fissures, as well as some saturated zone networks of solutional conduits and fissures. These networks are likely to result in groundwater flow in unexpected directions and potentially over long distances. Considerable further work is needed to develop better datasets on karst features, and to assess the role of karst in the limestones in this area. There is more information on gypsum karst in the area, which is well-developed and poses significant engineering hazards and challenges, and also impacts on the limestones which collapse into the gypsum karst. The presence of sulphate-rich groundwater and springs indicate the interconnection of limestone and gypsum sequences in the Permian strata in the area, highlighting the complexity and connectivity between different geologies.

Item Type:	Publication - Report
Funders/Sponsors:	British Geological Survey
Additional Information. Not used in RCUK Gateway to Research.:	This item has been internally reviewed, but not externally peer-reviewed.
Date made live:	01 May 2024 16:34 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/537368

Item Type:

Publication - Report

Funders/Sponsors:

British Geological Survey

Additional Information. Not used in RCUK Gateway to Research.:

This item has been internally reviewed, but not externally peer-reviewed.

Date made live:

01 May 2024 16:34 +0 (UTC)

URI:

https://nora.nerc.ac.uk/id/eprint/537368