Calcrete as a source of heterogeneity in Triassic fluvial sandstone aquifers (Otter Sandstone Formation, SW England)

Newell, A.J.. 2006 Calcrete as a source of heterogeneity in Triassic fluvial sandstone aquifers (Otter Sandstone Formation, SW England). In: Barber, R.D.; Tellam, J.H., (eds.) Fluid flow and solute movement in sandstones : the onshore UK Permo-Triassic red bed sequence. London, Geological Society of London, 119-127. (Special Publication, 263).

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Abstract/Summary

Carbonate is not generally considered as a potential source of large-scale heterogeneity in Permo-Triassic sandstone aquifers. This study shows that carbonate, in the form of early diagenetic calcrete, forms an abundant component of the Triassic Otter Sandstone Formation in south Devon. Three types of calcrete are described from the outcrop of this fluvial sandstone dominated aquifer: rhizocretions; calcrete sheets; and calcrete conglomerates. Data obtained from core plugs show that calcrete reduces sandstone permeability to less than 10–15 m2 and porosity to less than 12%. Calcrete can be sufficiently abundant to produce a significant (up to 30%) reduction in the total effective porosity of the aquifer. Moreover, calcrete conglomerates can form laterally extensive (up to 1 km) low-permeability sheets that will represent major baffles to vertical flow.

Item Type:	Publication - Book Section
Programmes:	BGS Programmes > Groundwater Management
Additional Keywords:	Aquifers, Calcretes, GroundwaterBGS, Groundwater, Aquifer characterisation, Major aquifer
NORA Subject Terms:	Earth Sciences
Related URLs:	http://www.bgs.ac.uk/research/groundwate...
Date made live:	29 Aug 2007 09:20 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/881

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