Temperature dependence of the strontium distribution coefficient in calcite; an experimental study from 408 degrees to 2008 degrees C and application to natural diagenetic calcites

Abstract

The temperature dependence of Sr coprecipitation with calcite was determined experimentally in solutions with Sr/Ca ratios and ionic strengths closely resembling marine pore fluids. Aragoniteto-calcite and dolomite-to-calcite transformations were conducted over a temperature range from 40؇ to 200؇C. Temperature dependence of the distribution coefficient of strontium in calcite (D ) is significant. c Sr D in aragonite-to-calcite experiments varied from 0.046 at 40؇C to c Sr 0.068 at 200؇C. D in dolomite-to-calcite experiments varied from c Sr 0.034 at 40؇C to 0.062 at 200؇C. Experimental values of D are somec Sr what dependent on the precursor phase.The experimental results are applied to natural diagenetic and hydrothermal calcites recovered from the sediment-covered Middle Valley part of the Juan de Fuca Ridge spreading center (Ocean Drilling Program Holes 857C and 858D). Low-Mg calcites from Hole 858D have Sr contents appropriate for their present-day in situ temperatures and pore-water Sr values. In contrast, high-Mg calcites from Hole 858D that precipitated from supersaturated pore waters at inferred high growth rates have elevated Sr contents relative to calculated equilibrium values. The Sr contents of calcites from Hole 857C are close to predicted equilibrium values in some instances but are substantially different in others. Deviations from predicted equilibrium Sr contents, especially in nodules, are attributed to the formation of mixed generations of carbonate precipitating with increasing burial depths and temperatures through pore waters with variable Sr composition.

A New Approach for Provenance Studies of Archaeological Finds: Inferences from Trace Elements in Carbonate Minerals of Alpine White Marbles by a Bench-to-Top μ-XRF Spectrometer

“…In Prali marble, the analysis of coexisting and cogenetic calcite and dolomite shows that higher contents of Sr and Fe occur in CaCO 3 mineral phase, suggesting the higher distribution coefficient of Sr and Fe in calcite than in dolomite as also supported by previous authors studying the temperature dependence of the distribution coefficient of strontium in calcite and dolomite [37,38]. However, from the observation of diagrams in Figure 2, the random scattering of the points representative of calcite (empty symbols) and dolomite (black symbols) leads to the conclusion that the concentration of trace elements, in each variety of marble, does not depend primarily on the type of carbonate mineral phase.…”

Calcification rate and temperature effects on Sr partitioning in coccoliths of multiple species of coccolithophorids in culture

“…This is nearly an order of magnitude greater than the temperature dependence of D Sr in calcite inferred from aragonite -calcite and dolomite -calcite transformation experiments (Malone and Baker, 1999). For calcification rate, the linear relationship in all species corresponds to a change in Sr/Ca ratios of 2.0% to 1.6% per 100 pg calcite/cell/day in the range of 100 to 1500 pg calcite/cell/day.…”

Calcium and strontium isotope fractionation in aqueous solutions as a function of temperature and reaction rate; I. Calcite

“…Furthermore, Tang et al, 2012 studied the effect of salinity parallel to the effect of rate of precipitation and found that it has an insignificant effect on the D Sr values. Also for biogenic calcite and experimental transformation of aragonite to calcite a positive or insignificant T dependence was observed (Katz et al, 1972;Jacobson and Usdowski, 1976;Baker et al, 1982;Stoessell et al, 1987;Lea et al, 1999;Humphrey and Howell, 1999;Malone and Baker, 1999;Stoll et al, 2002a,b).…”

“…In addition, the Sr/Ca ratio measured in aragonite has been widely used in paleooceanographic studies to estimate past sea surface temperatures (SST) (e.g., Smith et al, 1979;Rosenthal et al, 1997;Gagan et al, 1998). This elemental ratio is also used to understand the composition of past seawater, to study the diagenetic reactions that involve carbonate sediments (e.g., Lorens, 1981;Baker et al, 1982;Mucci and Morse, 1983;Richter and Liang, 1993;Banner, 1995;Humphrey and Howell, 1999;Malone and Baker, 1999). The Sr/Ca ratio in biogenic calcite was also correlated to both nutrient level and growth rate (e.g., Weinbauer and Velimirov, 1995;Stoll and Schrag, 2000;Stoll et al, 2002a,b).…”