Influence of temperature on the composition of magnesian calcite overgrowths precipitated from sea water

Journal Article · Wed Jul 01 04:00:00 EDT 1987 · Geochim. Cosmochim. Acta; (United States)

DOI:https://doi.org/10.1016/0016-7037(87)90186-4· OSTI ID:7222717

Mucci, A

A constant disequilibrium technique was used to determine the composition of magnesian calcite overgrowths precipitated on pure calcite seeds from artificial sea water at 5, 25 and 40/sup 0/C. The amount of magnesium incorporated in the overgrowths at a given temperature is independent of the precipitation rate over a wide range of saturation states and is believed to correspond to a composition in true equilibrium with sea water. The distribution coefficient of magnesium, D/sub Mg/sup 2 +///sup c/, in the magnesian calcite overgrowths increases almost linearly with temperature, being 0.0121 +- 0.0013 at 5/sup 0/C, 0.0172 +- 0.0022 at 25/sup 0/C, and 0.0271 +- 0.0013 at 40/sup 0/C. These values apply only to magnesian calcites precipitated from standard composition sea water, since a previous study has shown D/sub Mg/sup 2 +///sup c/ to be a function of the (Mg/sup 2 +/)(Ca/sup 2 +/) ratio in the parent solution. Results of this study are compared with values reported previously by other workers, and with the compositional distribution of naturally occurring magnesian calcite cements and ooids found in sea water. It appears that variations in temperature are not sufficient to account for the compositional variability of naturally occurring inorganic marine magnesian calcite cements.

• Research Organization: McGill Univ., Montreal, Quebec (Canada)
• OSTI ID: 7222717
• Journal Information: Geochim. Cosmochim. Acta; (United States), Journal Name: Geochim. Cosmochim. Acta; (United States) Vol. 51:7; ISSN GCACA
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580400* -- Geochemistry-- (-1989)
ALKALINE EARTH METAL COMPOUNDS
BUILDING MATERIALS
CALCITE
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CARBON COMPOUNDS
CARBONATE MINERALS
CARBONATES
CEMENTS
CHEMICAL COMPOSITION
CHEMISTRY
DOLOMITE
DYNAMIC FUNCTION STUDIES
EQUILIBRIUM
GEOCHEMISTRY
HYDROGEN COMPOUNDS
MAGNESIUM CARBONATES
MAGNESIUM COMPOUNDS
MATERIALS
MINERALS
OXYGEN COMPOUNDS
PRECIPITATION
SATURATION
SEAWATER
SEPARATION PROCESSES
TEMPERATURE EFFECTS
WATER