The relationship between the development of iron sulfide and barite nodules in the Cenomanian Chalk of England and the presence of a red hematitic pigment has been investigated using sulfur isotopes. In southern England where red and pink chalks are absent, iron sulfide nodules are widespread. Two typical large iron sulfide nodules exhibit δ34S ranging from −48.6‰ at their core to −32.6‰ at their outer margins. In eastern England, where red and pink chalks occur in three main bands, there is an antipathetic relationship between the coloured chalks and the occurrence of iron sulfide or barite nodules. Here iron sulfide, or its oxidised remnants, are restricted to two situations: (1) in association with hard grounds that developed originally in chalks that contained the hematite pigment or its postulated precursor FeOH3, or (2) in regional sulfidization zones that cut across the stratigraphy. In the Cenomanian Chalk exposed in the cliffs at Speeton, Yorkshire, pyrite and marcasite (both iron sulfide) nodules range in δ34S from −34.7‰ to +40.0‰. In the lower part of the section δ34S vary from −34.8‰ to +7.8‰, a single barite nodule has δ34S between +26.9‰ and +29.9‰. In the middle part of the section δ34S ranges from +23.8‰ to +40.0‰. In the sulfidization zones that cut across the Cenomanian Chalk of Lincolnshire the iron sulfide nodules are typically heavily weathered but these may contain patches of unoxidised pyrite. In these zones, δ34S ranges from −32.9‰ to +7.9‰. The cross-cutting zones of sulfidization in eastern England are linked to three basement faults – the Flamborough Head Fault Zone, the Caistor Fault and the postulated Wash Line of Jeans (1980) – that have affected the deposition of the Chalk. It is argued that these faults have been both the conduits by which allochthonous fluids – rich in hydrogen sulfide/sulfate, hydrocarbons and possibly charged with sulfate-reducing bacteria – have penetrated the Cenomanian Chalk as the result of movement during the Late Cretaceous or Cenozoic. These invasive fluids are associated with (1) the reduction of the red hematite pigment or its praecursor, (2) the subsequent development of both iron sulfides and barite, and (3) the loss of overpressure in the Cenomanian Chalk and its late diagenetic hardening by anoxic cementation. Evidence is reviewed for the origin of the red hematite pigment of the coloured chalks and for the iron involved in the development of iron sulfides, a hydrothermal or volcanogenic origin is favoured.
Andrews J.E., Kendall, A.C. and Hall, A. 2015. Microbial crust with Frutextites(?) and iron staining in chalks: Albian–Cenomanian Boundary, Hunstanton, UK. Geological Magazine, 152, 1–11.
Antler, G., Turchyn, A.V., Herut, B., Davies, A., Rennie, V.C.F. and Sivan, O. 2014. Sulfur and oxygen isotope tracing of sulfate driven anaerobic methane oxidation in estuarine sediments. Estuarine, Shelf, and Coastal Science, 142, 4–11.
Bannister, F.A. 1932. The distinction of pyrite from marcasite in nodular growths. Mineralogical Magazine, 23, 179–187.
Bower, C.R. and Farmery, J.T. 1910. The zones of the Lower Chalk of Lincolnshire. Proceedings of the Geologists’ Association, 11, 333–359.
Clayton, C.J. 1986. The chemical environment of flint formation in Upper Cretaceous chalks. In: G. de C. Sieveking and M.B. Hart (Eds), The scientific study of flint and chert, pp. 43–54. Cambridge University Press.
Gallois, R.W. and Morter, A.A. 1982. The stratigraphy of the Gault of East Anglia. Proceedings of the Geologists’ Association, 93, 351–368.
Hancock, J.M. 1990. Cretaceous. In: K.W. Glennie (Ed.), Introduction to the Petroleum Geology of the North Sea (3rd Edition), pp. 255–272. Blackwell Scientific Publication.
Hildreth, P. N. 2013. The Vale House Flints Member, a flint-rich unit of the Burnham Chalk Formation of the Northern Province, East Yorkshire and Lincolnshire, UK. Proceedings of the Yorkshire Geological Society, 59, 177–186.
Hu, X-F., Jeans, C.V. and Dickson, J.A.D. 2012. Geochemical and stable isotope patterns of calcite cementation in the Upper Cretaceous Chalk, UK: Direct evidence from calcite-filled vugs in brachiopods. Acta Geologica Polonica, 62, 143–172.
Hu, X-F., Long, D. and Jeans, C.V. 2014. A novel approach to the study of the development of the Chalk’s smectite assemblage. Clay Minerals, 49, 279–299.
Jeans, C.V. 1967. The Cenomanian Rocks of England, 156 p. Unpublished PhD thesis, University of Cambridge.
Jeans, C.V. 1973. The Market Weighton Structure: tectonics, sedimentation and diagenesis during the Cretaceous. Proceedings of the Yorkshire Geological Society, 39, 409–444.
Jeans, C.V. 1978. Silicifications and associated clay assemblages in the Cretaceous marine sediments of southern England. Clay Minerals, 12, 102–126.
Jeans, C.V. 1980. Early submarine lithification in the Red Chalk and Lower Chalk of Eastern England: a bacterial control model and its implications. Proceedings of the Yorkshire Geological Society, 43, 81–157.
Jeans, C.V. 2006. Clay mineralogy of the Cretaceous strata of the British Isles. Clay Minerals, 41, 47–150.
Jeans, C.V., Merriman, R.J., Mitchell, J.G. and Bland. D.J. 1982. Volcanic clays in the Cretaceous of southern England and Northern Ireland. Clay Minerals, 17, 105–56.
Jeans, C.V. Long, D., Hall, M.A., Bland, D.J. and Cornford C.1991. The geochemistry of the Plenus Marls at Dover, England: evidence of fluctuating oceanographic conditions and of the glacial control during the development of the Cenomanian-Turonian δ13 anomaly. Geological Magazine, 126, 603–632.
Jeans, C.V., Wray, D.S., Merriman, R.J. and Fisher, M.J. 2000. Volcanic clays in Jurassic and Cretaceous strata of England and the North Sea Basin. Clay Minerals, 35, 25–55.
Jeans, C.V., Hu, X-F. and Mortimore, R.N. 2012. Calcite cements and the stratigraphical significance of the marine δ13C carbonate reference curve for the Upper Cretaceous Chalk of England. Acta Geologica Polonica, 62, 173–196.
Jeans, C.V., Long, D., Hu, X-F. and Mortimore, R.N. 2014. Regional hardening of Upper Cretaceous Chalk in eastern England, UK: trace element and stable isotope patterns in the Upper Cenomanian and Turonian chalk and their significance. Acta Geologica Polonica, 64, 419–455.
King, C., Bailey, H.W., Burton, C. and King, A.D. 1989. Cretaceous of the North Sea. In: D.G. Jenkins and J.W. Murray (Eds), Stratigraphical atlas of fossil foraminifera (2nd Edition), pp. 372–417. The British Micropalaeontological Society Series, John Wiley and Sons.
McConville, P., Boyce, A.J., Fallick, A.E., Harte, B. and Scott, E.M. 2000. Sulfur isotope variations in diagenetic pyrite from core plug to sub-millimetre scales. Clay Minerals, 35, 303–311.
Mitchell, S.F. 1995. Lithostratigraphy and biostratigraphy of the Hunstanton Formation (Red Chalk, Cretaceous) succession at Speeton, North Yorkshire, England. Proceedings of the Yorkshire Geological Society, 50, 285–303.
Mortimore, R.N., Wood, C.J. and Gallois, R.W. 2001. British Upper Cretaceous Stratigraphy. Geological Conservation Review Series23, 558 pp. Joint Nature Conservation Committee; Peterborough, U.K.
Mortimore, R.N. 2013. Geoconservation and the advancement of geosciences: lessons from the Chalk of England. Proceedings of the Geologists’ Association, 124, 593–611.
Schmid, F. and Spaeth, Ch. 1991. Der braunrot Feuerstein aus dem Turon von Helgoland. Geologisches Jahrbuch, Reihe A, Heft 120, 97–104.
Schmid, F and Spaeth, Ch. 1978. Zur Alterstellung des braunroten Kreide-Feuersteins von Helgoland. Neues Jahrbuch für Geologie und Paläontologie, Monatshefte, 427–429.
Wiese, F. 2009. The Söhlde Formation (Cenomanian, Turonian) of NW Germany: shallow marine pelagic red beds. in Cretaceous Oceanic Red Beds: Stratigraphy, Composition, Origins, and Paleoceanographic and Paleoclimatic Significance. SEPM Special Publication No. 91, 153–170.
Wood, C.J. and Smith, E.G. 1978. Lithostratigraphical classification of the Chalk in North Yorkshire, Humberside and Lincolnshire. Proceedings of the Yorkshire Geological Society,42, 263–287.
Wood, C.J. and Schmid, F. 1991. Upper Cretaceous of Helgoland (NW Germany): Lithology, Palaeontology and Biostratigraphy. Geologisches Jahrbuch, A120, 37–61.
Wood, C.J. and Mortimore, R.N. 1995. An anomalous Black Band succession (Cenomanian-Turonian boundary interval) at Melton Ross, Lincolnshire, eastern England and its international significance. Berliner Geowissenschaftliche Abhandlungen Reihe,E 16 (Gundolf Ernst Festschrift), 277–287.
Wood, C J., Batten, D.J., Mortimore, R.N. and Wray, D.S. 1997. The stratigraphy and correlation of the Cenomanian – Turonian boundary interval succession in Lincolnshire, eastern England. Freiberger Forschungshefte,C468, 333–346.
Voigt, S., Wagreich, M., Surlyk, F., Walaszczyk, I., Uličný, D., Čech, S., Voigt, T., Wiese. F., Wilmsen, M., Niebuhr, B., Reich, M., Kunk, H., Michalík, J., Jagt, J., Felder, P. and Schlup, A. 2008. Cretaceous. In: McCann, T. (Ed.), The Geology of Central Europe. Volume 2: Mesozoic and Cenozoic. Geological Society, London, 923–997.