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Geochemical constraints on the origin of enigmatic cemented chalks, Norfolk, UK

G. Woolhouse, J. E. Andrews, A. Marca-Bell and P. F. Dennis
Geochemical constraints on the origin of enigmatic cemented chalks, Norfolk, UK
Geological Magazine (March 2009) 146 (2): 291-299

Abstract

Very hard cemented chalk stacks and crusts found locally in the upper part of the Cretaceous Chalk of north Norfolk, UK, are related to solution features. The solution features, mainly pipes and caves, formed after deposition of the overlying Middle Pleistocene Wroxham Crag, probably by routing of sub-glacial, or glacial, melt-waters derived from late Pleistocene glaciers. New geochemical (particularly stable isotope) data shows that cementation of the chalks, although related spatially to the solution features, was not caused by glacier-derived waters. The carbon isotope composition of the chalk cements is typically around -9.5 per mil, indicative of biologically active soils. Moreover, the oxygen isotope compositions of the cements, around -5 per mil, are incompatible with water delta (super 18) O values much below -9 to -10 per mil (which probably precludes isotopically negative glacier-derived water), as resulting palaeo-temperatures are below zero. Taken together, the isotope data suggest chalk cementation occurred under interglacial conditions similar to the present. Dissolved calcium carbonate for cementation came from dissolution of reworked chalk in overlying MIS 12 glacial tills.


ISSN: 0016-7568
EISSN: 1469-5081
Coden: GEMGA4
Serial Title: Geological Magazine
Serial Volume: 146
Serial Issue: 2
Title: Geochemical constraints on the origin of enigmatic cemented chalks, Norfolk, UK
Affiliation: University of East Anglia, School of Environmental Sciences, Norwich, United Kingdom
Pages: 291-299
Published: 200903
Text Language: English
Publisher: Cambridge University Press, London, United Kingdom
References: 32
Accession Number: 2009-048453
Categories: Isotope geochemistrySedimentary petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 3 tables, sketch map
N52°25'00" - N53°00'00", E00°10'00" - E01°45'00"
Country of Publication: United Kingdom
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, Copyright, Cambridge University Press. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 200926
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