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A mechanism for the formation of the mineralized Mn deposits at Merehead Quarry, Cranmore, Somerset, England

Published online by Cambridge University Press:  05 July 2018

R. Turner
R. Turner*
Affiliation:
The Drey, Allington Track, Allington, Salisbury SP4 0DD, UK
*
*E-mail: rturner@imbuia-holdings.com
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Abstract

Mississippi Valley type galena deposits emplaced into Carboniferous limestones throughout the Mendip Hills during the late Permian or Triassic period were locally exposed to the action of seawater during the Jurassic period following regional uplift and erosion of the intervening strata. Oxidation of galena initiated the deposition of manganate minerals from the seawater, and these adsorbed heavy metals from both the seawater and local environment. A subsequent hydrothermal event heated the lead-manganate deposits causing decomposition of the galena and creating the conditions which led to the formation of the suite of unusual secondary minerals – including a number of rare oxychlorides – now found at Merehead. Heating of the manganate phases converted them to Mn oxides and released the entrained heavy metals which were then incorporated into unusual mineral phases. The impervious Mn oxide coating which enclosed the cooling Pb-rich areas isolated them chemically, leading to closed-system behaviour. The high-T phases at Merehead are similar to those found in the Pb-bearing silicic skarns at Långban, whilst the suite of secondary minerals which evolved in the closed-system environments bears striking similarities to the ‘anomalous sequence’ of minerals found at the Mammoth-St. Antony Mine. The complexity of these formation processes probably explains the rarity of Mendip-type Pb-Mn deposits. The collective importance of the disconformity, the hydrothermal event, and subsequent sealing of the deposits are recognized for the first time, and the temperature of the hydrothermal event is shown to have been much greater than has heretofore been realized. Silurian volcanic strata underlying the Carboniferous limestones which have previously been assumed to be the source of heavy metals are shown to have been uninvolved in the process.

Keywords

mereheaditeMn depositsoxychlorideSomersetMendipMereheadEngland
Type
Research Article
Information
Mineralogical Magazine , Volume 70 , Issue 6 , December 2006 , pp. 629 - 653
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2006

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References

Abdul-Samad, F., Thomas, J.H., Williams, P.A., Bideaux, R.A. and Symes, R.F. (1982) Mode of formation of some rare copper (II) and lead (II) minerals from aqueous solution, with particular reference to deposits at Tiger, Arizona. Transition Metal Chemistry, 7, 32–37.CrossRefGoogle Scholar
Anthony, J.W., Bideaux, R.A., Bladh, K.W. and Nichols, M.C. (1997) Handbook of Mineralogy, vol. III, p. 143. Mineral Data Publishing, Tucson, Arizona.Google Scholar
Bideaux, R.A. (1980) Famous Mineral Localities – Tiger, Arizona. Mineralogical Record, 11, 155–181.Google Scholar
Brugger, J. and Meisser, N. (2006) Manganese-rich assemblages in the Barrhorn Unit, Turtmanntal, Central Alps. Switzerland. The Canadian Mineralogist, 44, 229–248.CrossRefGoogle Scholar
Burr, P.S. (1996) Famous mineral localities: The Higher Pitts Mine, Mendip Hills, Somerset, England. Mineralogical Record, 27, 245–262.Google Scholar
Cama, J., Acero, P., Ayora, C., and Lobo, A. (2005) Galena surface reactivity at acidic pH and 25°C based on flow-through and in situ AFM experiments. Chemical Geology, 214, 309–330.CrossRefGoogle Scholar
Carlos, B.A., Chipera, S.J., Bish, D.L. and Craven, S.J. (1993) Fracture-lining manganese oxide minerals in silicic tuff, Yucca Mountain, Nevada, U.S.A. Chemical Geology, 107, 47–69.CrossRefGoogle Scholar
Creasey, S.C. (1950) Arizona Zinc and Lead Deposits. Arizona Bureau of Mines Bulletin 156, pp. 63–84.Google Scholar
Dermatas, D., Dadachov, M., Dutko, P., Menounou, N., Arienti, P. and Shen, G. (2004) Weathering of lead in Fort Irwin firing range soils. Global Nest, 6, 167–175.Google Scholar
Din, V.K., Symes, R.F. and Williams, C.T. (1986) Lithogeochemical study of some Mendip county rocks with particular reference to boron. Bulletin of the British Museum (Natural History), Geological Series Miscellania II, 40, 247–258.Google Scholar
Dyer, A., Pillinger, M., Harjula, R. and Amin, S. (2000) Sorption characteristics of radionuclides on synthetic birnessite-type layered manganese oxides. Journal of Materials Chemistry, 12, 1381–1386.Google Scholar
Edwards, R., Gillard, R.D. and Williams, P.A. (1992) Studies of secondary mineral formation in the PbO-H2O-HCl system. Mineralogical Magazine, 56, 53–65.CrossRefGoogle Scholar
Green, G.W. (1958) The central Mendip lead-zinc orefield. Bulletin of the Geological Survey of Great Britain, 14, pp. 70–90.Google Scholar
Grice, J.D. and Dunn, P.J. (2000) Crystal-structure determination of pinalite. American Mineralogist, 85, 806–809.CrossRefGoogle Scholar
Holtstam, D. and Langhof, J. (editors) (1999) Långban, the Mines, their Minerals, Geology and Explorers. Christian Weise Verlag, München, Germany.Google Scholar
Kim, B.S., Hayes, R.A., Prestidge, C.A., Ralston, J. and Smart, R. (1995) Scanning tunnelling microscopy studies of galena: The mechanisms of oxidation in aqueous solution. Langmuir, 11, 2554–2562.CrossRefGoogle Scholar
Krivovichev, S.V. and Burns, P.C. (2000 a) Crystal chemistry of basic lead carbonates. Part 1, crystal structure of synthetic shannonite. Mineralogical Magazine, 64, 1063–1068.CrossRefGoogle Scholar
Krivovichev, S.V. and Burns, P.C. (2000 b) Crystal chemistry of basic lead carbonates. Part 2, crystal structure of synthetic ‘plumbonacrite’. Mineralogical Magazine, 64, 1069–1075.CrossRefGoogle Scholar
Lindqvist, B. and Charalampides, G. (1987) Stability and kinetic studies of synthetic solid solutions in the kentrolite-melanotekite series. Geologiska Foreningens i Stockholm foerhandlingar, 109, 73–82.CrossRefGoogle Scholar
Matagi, S.V., Swai, D. and Mugabe, R. (1998) A review of heavy metal removal mechanisms in wetlands. African Journal of Tropical Hydrobiology, 8, 23–35.Google Scholar
Means, J.L., Crerar, D.A., Borcsik, M.P. and Duguid, J.O. (1978) Radionuclide adsorption by manganese oxides and implications for radioactive waste disposal. Nature, 274, 44–47.CrossRefGoogle Scholar
Mercy, M.A., Rock, P.A., Casey, W.H. and Mokarram, M.H. (1998) Gibbs energies of formation for hydrocerussite and hydrozincite. American Mineralogist, 83, 739–745.CrossRefGoogle Scholar
Mikhlin, Y.L., Romanchenko, A.S. and Shagaev, A.A. (2006) Scanning probe microscopy studies of PbS surfaces oxidized in air and etched in aqueous acid solutions. Applied Surface Science, 252, 5645–5658.CrossRefGoogle Scholar
Moorbath, S. (1962) Lead isotope abundance studies on mineral occurrences in the British Isles and their geological significance. Philosophical Transactions of the Royal Society of London, Series A, Mathematical and Physical Sciences, 254, 295–360.Google Scholar
Morse, G. (editor) (2004) Minerals of the Mendips. Published by the Southern Branch of the Russell Society.Google Scholar
Moses, C.O. and Ilton, E.S. (1998) Surface and solution-interface geochemistry of PbS and PbSe minerals. Office of Science and Technology Investigation final report DE-FG02-93ER14373, 13 pp.Google Scholar
Nava, J.L. and Gonzalez, I. (2005) Los electrodos de pasta de carbono en el estudio electroquímico de minerales metálicos. Química Nova, 28, 5.CrossRefGoogle Scholar
Parc, S., Nahon, D., Tardy, Y. and Veillard, P. (1989) Estimated solubility products and fields of stability for cryptomelane, nsutite, birnessite, and lithiophorite based on natural lateritic weathering sequences. American Mineralogist, 74, 466–475.Google Scholar
Parkhouse, S.J. (2004) Geodiversity Audit of Active Aggregate Quarries – Torr Works, Cranmore, Somerset, England. http://www.somerset.gov.uk/.Google Scholar
Post, J.E. (1999) Manganese oxide minerals: Crystal structures and economic and environmental significance. Proceedings of the National Academy of Sciences of the USA, 96, 3447–3454.CrossRefGoogle ScholarPubMed
Prince, K.C., Heun, S., Gregoratti, L., Barinov, A., and Kisinova, M. (2002) Long Term Oxidation Behaviour of Lead Sulfide Surfaces. Lecture Notes in Physics, vol. 588, pp. 111–120. Springer, Berlin, Heidelberg.Google Scholar
Scheckel, K.G., Impellitari, C.K. and Ryan, J.A. (2001) Assessment of a sequential extraction procedure for perturbed lead contaminated samples with and without phosphorus amendments. UK Environmental Protection Agency Risk Management Research Laboratory.Google Scholar
Symes, R.F. and Embrey, P.G. (1977) Mendipite and other rare oxychloride minerals from the Mendip Hills, Somerset, England. Mineralogical Record, 8, 298–303.Google Scholar
Symes, R.F., Cressey, G., Criddle, A.J., Stanley, C.J., Francis, J.G. and Jones, G.C. (1994) Parkinsonite, (Pb,Mo,☐)8O8Cl2, a new mineral from Merehead Quarry, Somerset. Mineralogical Magazine, 58, 59–68.CrossRefGoogle Scholar
Takahashi, T. (1960) Supergene alteration of lead and zinc deposits in limestone. Economic Geology, 55, 1083–1115.CrossRefGoogle Scholar
Turner, R.W. (2005) A note on crednerite from Merehead Quarry. Newsletter of the Russell Society, p. 47.Google Scholar
Turner, R.W. and Rumsey, M. (2007) The Manganese-Hosted Mineral Deposits of the Mendip Hills (in prep.).Google Scholar
Welch, M.D., Schofield, P.F., Cressey, G. and Stanley, C.J. (1996) Cation ordering in lead-molybdenum-vanadium oxychlorides. American Mineralogist, 81, 1350–1359.CrossRefGoogle Scholar
Welch, M.D., Criddle, A.J. and Symes, R.F. (1998) Mereheadite, Pb2O(OH)Cl: a new litharge-related oxychloride from Merehead Quarry, Cranmore, Somerset. Mineralogical Magazine, 62, 387–393.CrossRefGoogle Scholar
Welch, M.D., Cooper, M.A., Hawthorne, F.C. and Criddle, A.J. (2000) Symesite, Pb10(SO4)O7Cl4(H2O), a new PbO-related sheet mineral. American Mineralogist, 85, 1526–1533.CrossRefGoogle Scholar
Worley, N.E. and Ford, T.D. (1977) Mississippi Valley type orefields in Britain. Bulletin of the Peak District Mines Historical Society, 6, 201–208.Google Scholar