Behaviour of magnesium and strontium during the transformation of coral aragonite to calcite in aquatic environments

Yoshioka, Sayoko; Ohde, Shigeru; Kitano, Yasushi; Kanamori, Nobuko

doi:10.1016/0304-4203(86)90074-5

Cited by 27 publications

(13 citation statements)

References 12 publications

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“…It is known that significant amounts of Na and Mg are adsorbed, as ionic forms, on the surface of coral skeletons and that the ions adsorbed on the skeletal surface can be removed by treating the skeletons with distilled/ deionized water (DDW) or a very weak acid solution (e.g., Amiel et al, 1973;Yoshioka et al, 1985Yoshioka et al, , 1986Mitsuguchi et al, 2001;Watanabe et al, 2001b). Our element/Ca ratio data are probably completely free from the influence of such adsorption, because we treated coral samples with DDW, very dilute HNO 3 and H 2 O 2 , under ultrasonic agitation (see Section "Materials and Methods").…”

Section: Indicate Results Of 5 Coral Powder Samples (Shown As Differementioning

confidence: 99%

Na/Ca variability in coral skeletons

2010

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Section: Indicate Results Of 5 Coral Powder Samples (Shown As Differementioning

confidence: 99%

Na/Ca variability in coral skeletons

2010

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“…This is confirmed by X-ray and cathodoluminescence analyses. The lack of calcite may be due to the absence of calcite nuclei or to the presence of inhibiting parameters, such as high Mg/Ca ratios resulting from mixing of fresh and marine waters (Kitano and Hood 1962;Bischoff 1968;Matthews 1968;McLester et al 1970;Kitano et al 1980;Ohde and Kitano 1981;Mucci and Morse 1983;Busenberg and Plummer 1985;Yoshioka et al 1986;Burton and Walter 1987;McClain et al 1992;Rushdi et al 1992). In this case, biogenic aragonite is dissolved.…”

Section: Alteration Of Geochemical Proxiesmentioning

confidence: 92%

“…Acropora species and age Modern Acropora Cross and Cross (1983) a 7,094106 8.090.12 Acropora palmata, modern Yoshioka et al (1986) a 7,900 to 8,500 9.01 to 9.7 Acropora sp., modern Aizawa and Akaiwa (1989) 7,900 9.01 Acropora porites, modern Bar- Matthews et al (1992) …”

mentioning

confidence: 99%

Diagenesis and its impact on Sr/Ca ratio in Holocene Acropora corals

Ribaud-Laurenti¹,

Hamelin

Montaggioni³

et al. 2001

Int J Earth Sci

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The effect of early diagenesis on Sr/Ca ratios encapsulated in coral skeletons was evaluated by comparing mineralogical, structural and geochemical characteristics of modern and Holocene, branching Acropora colonies. The modern specimens (Acropora danai, Acropora formosa) come from RØunion island (Western Indian Ocean) and the Great Barrier Reef of Australia respectively. The Sr/Ca ratios of modern specimens range from 9.08 to 9.37 mmol/mol. The fossil acroporids (Acropora group danai-robusta) were collected from a 50-m core drilled through a barrier reef in Tahiti island; their C-14 ages range from 3,200 to 10,200 calendar years B.P. Fossil skeletons are 100% aragonite. Earlier diagenesis has occurred in the marine environment; it is expressed by growth of secondary inorganic aragonite over primary skeletal aragonite needles, development of syntaxial aragonite cements within intraskeletal cavities and decrease in size of original 1±1,050-m-wide pores (residual porosity ranges from 25 to 28%), which results in a volume reduction by 34 to 49%. Cementation increases with increasing age of the corals. Later diagenesis has occurred in a mixed marine±freshwater environment. It includes partial dissolution of skeletal and growth of cement aragonite fibres in the form of spherolites, irregular meshes of large squarely terminated laths; this results in an increase in porosity from 30 to 59%. By reference to modern well-preserved acroporids, this diagenetic alteration has led to an increase of Sr/Ca values (from 9.08±9.37 to 8.89±10.55 mmol/mol). This variation in Sr/Ca ratio can be linked to the increase in the amount of Sr-enriched cements relative to the volume of the skeletal aragonite and to a more homogeneous distribution of these cements throughout the skeleton. The uncritical use of Sr/Ca ratios as paleothermometers from diagenetically altered skeletons may cause serious misinterpretations. Accordingly, estimate of the degree of diagenetic alteration in skeletons is a prerequisite to any paleoclimatic reconstruction based on coral records.

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“…amino acids (Allen et al, 1970)) and the behaviour of magnesium and strontium during the transformation (e.g. Katz et al, 1972;Yoshioka et al, 1986) have also been investigated. Nevertheless, a number of significant issues remain unclear, specifically the effect of the molar volume change on the transformation mechanism, the conditions under which the transformation is pseudomorphic and the role of fluid composition on the replacement process.…”

Section: Introductionmentioning

confidence: 99%