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Coordination of Sr and Mg in calcite and aragonite

Published online by Cambridge University Press:  05 July 2018

A. A. Finch  and
N. Allison
A. A. Finch*
Affiliation:
School of Geography and Geosciences, University of St Andrews, Irvine Building, St Andrews, Fife KY16 9AL, UK
N. Allison
Affiliation:
School of Geography and Geosciences, University of St Andrews, Irvine Building, St Andrews, Fife KY16 9AL, UK
*
E-mail: aaf1@st-and.ac.uk
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Abstract

Strontium and Mg in calcite and aragonite are widely used as proxies of temperature in palaeoenvironmental reconstructions. We use X-ray absorption fine structure (XAFS) to examine Sr and Mg substitution in calcite and aragonite. We have measured the K-edge X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) of Mg and Sr-bearing calcite and aragonite, plus the carbonates: strontianite, hydromagnesite, magnesite, dolomite and a suite of calcites with differing amounts of Mg. The Sr substitutes ideally for Ca in aragonite but causes a small (2%) dilation of the site. Strontium substitutes for octahedral Ca in calcite but with a 6.5% dilation and distortion. Magnesium in the calcites studied provides a variable XANES indicating that the Mg structural state in calcite is variable. Refinement of EXAFS gives Mg–O bond distances of ∼2.12 Å, which are much smaller than the Ca–O bond distance of 2.35 Å but consistent with published amounts of relaxation of the calcite structure. The XANES and EXAFS are consistent with a model whereby some calcites contain nanodomains, e.g. of dolomite and/or huntite structures. The variability in the XANES can be explained by domains of different types and/or sizes. Substitution of Mg into aragonite has 9-fold coordination but relatively short bond distances (2.08 Å) demonstrating either: (1) substantial distortion of the site; or (2) that Mg is accommodated in nanodomains of an unknown phase. Variability in the Mg structural state in calcite may be linked to the variety of temperature dependences observed, e.g. in foraminiferal calcite

Keywords

EXAFSXANESimpuritiespalaeo-environmental proxiescalcitearagonite
Type
Research Article
Information
Mineralogical Magazine , Volume 71 , Issue 5 , October 2007 , pp. 539 - 552
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2007

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References

Akao, M., Marumo, F. and Iwai, S. (1974) The crystal structure of hydromagne site. Acta Crystallographica, B30, 2670–2672.Google Scholar
Allison, N. and Finch, A.A. (2007) High temporal resolution Mg/Ca and Ba/Ca records in modern Porites lobata corals. Geochemistry Geophysics Geosy stems, 8, Q05001, doi:10.1029/2006GC001477.Google Scholar
Beck, J.W., Edwards, R., Ito, E., Taylor, F.W., Recy, J., Rougerie, F., Joannot, P. and Henin, C. (1992) Seasurface temperature from coral skeletal strontium/ calcium ratios. Science, 257, 644–647.CrossRefGoogle Scholar
Cabaret, D., Sainctavit, P., Ildefonse, P. and Flank, A.M. (1998) Full multiple scattering calculations of the X–ray absorption near edge structure at the Mg K–edge in pyroxene. American Mineralogist, 83, 300–304.CrossRefGoogle Scholar
Dollase, W.A. and Reeder, R.J. (1986) Crystal structure refinement of huntite, CaMg3(CO3)4, with X–ray powder data. American Mineralogist, 71, 163–166.Google Scholar
Falini, G., Fermani, S., Gazzano, M. and Ripamonti, A. (1998) Structure and morphology of synthetic magnesium calcite. Journal of Materials Chemistry, 8, 1061–1065.CrossRefGoogle Scholar
Finch, A.A., Allison, N., Sutton, S.V. and Newville, M. (2003) Strontium in coral aragonite: 1. Characterisation of Sr co–ordination by EXAFS. Geochimica et Cosmochimica Acta, 67, 1189–1194.CrossRefGoogle Scholar
Gaetani, G.A. and Cohen, A.L. (2006) Element partitioning during precipitation of aragonite from seawater: A framework for understanding paleoproxies. Geochimica et Cosmochimica Acta, 70, 4617–4634.CrossRefGoogle Scholar
Harding, M.M. (2006) Small revisions to predicted distances around metal sites in proteins. Acta Crystallographica, D62, 678–682.Google Scholar
Hedin, L. and Lundqvist, S. (1969) Effects of electronelectron and electron–phonon interactions on the one–electron states of solids. Solid State Physics, 23, 1–181.Google Scholar
Jarosch, D. and Heger, G. (1986) Neutron–diffraction refinement of the crystal–structure of aragonite. Tschermaks Mineralogische et Pettrographische Mitteilungen, 35, 127–131.Google Scholar
Jarosch, D. and Heger, G. (1988) Neutron diffraction investigation of strontianite. Bulletin de Minéralogie, 111, 139–142.CrossRefGoogle Scholar
Kinsman, D.J.J. and Holland, H.D. (1969) The coprecipitation of cations with CaCO3: IV. The coprecipitation of Sr2+ with aragonite between 16 and 96ºC. Geochimica et Cosmochimica Acta, 33, 1–17.CrossRefGoogle Scholar
Lea, D.W. (2003) Elemental and isotopic proxies of marine temperatures. Pp. 365–390 in: The Oceans and Marine Geochemistry (Elderfield, H., editor). Treatise on Geochemistry, 6, Elsevier–Pergamon, Oxford, UK.Google Scholar
Lee, Y.J., Reeder, R.J., Wenskus, R.W. and Elzinga, E.J. (2002) Structural relaxation in the MnCO3–CaCO3 solid solution: a Mn K–edge EXAFS study. Physics and Chemistry of Minerals, 29, 585–594.CrossRefGoogle Scholar
Li, D., Peng, M. and Murata, T. (1999) Coordination and local structure of Mg in silicate minerals and glasses: Mg K–edge XANES study. The Canadian Mineralogist, 37, 199–206.Google Scholar
Maslen, E.N., Streltsov, V.A. and Streltsova, N.R. (1995) Electron density and optical anisotropy in rhombohedral carbonates. III. Synchrotron X–ray studies of CaCO3, MgCO3 and MnCO3 . Acta Crystallographica, B51, 929–939.Google Scholar
Paquette, J. and Reeder, R.J. (1995) Relationship between surface–structure, growth–mechanism, and trace–element incorporation in calcite. Geochimica et Cosmochimica Acta, 59, 735–749.CrossRefGoogle Scholar
Pingitore, N.E. J., Lytle, F.W., Davies, B.M., Eastman, M.P., Eller, P.G. and Larson, E.M. (1992) Mode of incorporation of Sr2+ in calcite: determination by X–ray absorption spectroscopy. Geochimica et Cosmochimica Acta, 56, 1531–1538.CrossRefGoogle Scholar
Plummer, L.N. and Busenberg, E. (1987) Thermodynamics of aragonite–strontianite solid solutions: results from stoichiometric solubility at 25 and 76ºC. Geochimica et Cosmochimica Acta, 51, 1393.CrossRefGoogle Scholar
Reeder, R.J., Lamble, G.M. and Northrup, P.A. (1999) XAFS study of the coordination and local relaxation around Co2+, Zn2+, Pb2+ and Ba2+ trace elements in calcite. American Mineralogist, 84, 1049–1060.CrossRefGoogle Scholar
Reksten, K. (1990) Superstructures in calcite. American Mineralogist, 75, 807–812.Google Scholar
Sankar, G., Gleeson, D., Catlow, C.R., Thomas, J.M. and Smith, A.D. (2001) The architecture of Mg(II) catalysts in MAPO–36 solid acid catalysts. Journal of Synchrotron Radiation, 8, 625–627.CrossRefGoogle ScholarPubMed
Stoll, H.M., Klaas, C.M., Probert, I., Encinar, J.R. and Alonso, J.I.G. (2002) Calcification rate and temperature effects on Sr partitioning in coccoliths of multiple species of coccolithophorids in culture. Global and Planetary Change, 34, 153–171.CrossRefGoogle Scholar
Suzuki, Y., Morgan, P.E.D. and Niihara, K. (1998) Use of a high flux instrument for a mineral: X–ray powder diffraction pattern of CaMg(CO3)2. Powder Diffraction, 13, 216–221.CrossRefGoogle Scholar
Tsipursky, S.J. and Buseck, P.R. (1993) Structure of magnesian calcite from sea urchins. American Mineralogist, 78, 775–781.Google Scholar
Valle–Fuentes, F.–J., Garcia–Guinea, J., Cremades, A., Correcher, V., Sanchez–Moral, A., Gonzalez–Martin, R., Sanchez–Munoz, L. and Lopez–Arce, P. (2007) Low–magnesium uranium calcite with a high degree of crystallinity and gigantic luminescence. Applied Radiation and Isotopes, 65, 147–154.CrossRefGoogle ScholarPubMed
von Barth, U. and Hedin, L. (1972) A local exchangecorrelation potential for the spin polarized case: I. Journal of Physics C, 5, 1629–1642.Google Scholar
Wenk, H.–R., Meisheng, H., Lindsey, T. and Morris, J.W. J.. (1991) Superstructures in ankerite and calcite. Physics and Chemistry of Minerals, 17, 527–539.CrossRefGoogle Scholar
Wong, J., George, G.N., Pickering, I.J., Rek, Z.U., Rowen, M., Tanaka, T., Via, G.H., de Vries, B., Vaughan, D.E.W. and Brown, G.E., Jr. (1994) New opportunities in XAFS investigation in the 1–2 keV region. Solid State Communications, 92, 559–562.CrossRefGoogle Scholar
Wu, Z., Mottana, A., Marcelli, A., Natioli, C.R. and Paris, E. (1996) Theoretical analysis of X–ray absorption near–edge structure in forsterite Mg2SiO4–Pbnm, and fayalite, Fe2SiO4–Pbnm atroom temperature and extreme conditions. Physics and Chemistry of Minerals, 23, 193–204.CrossRefGoogle Scholar