Isotopic, chemical and textural relations during the experimental alteration of biogenic high-magnesian calcite

Details Isotopic, chemical and textural relations during the experimental alteration of biogenic high-magnesian calcite Isotopic, chemical and textural relations during the experimental alteration of biogenic high-magnesian calcite

Apr 1986

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1986gecoa..50..495t&link_type=abstract

Geochimica et Cosmochimica Acta, vol. 50, Issue 4, pp.495-506

Other

1

Scientific paper

Dissolution runs with four biogenic high magnesian calcites (HMC) of different magnesium content were conducted in distilled water saturated with 100% CO 2 and 3% CO 2 at 70°C and 35°C in order to study the mechanism of alteration of HMC to low magnesian calcite (LMC). The isotopic composition ( 13 C and 18 O ) of the solutions (-30%. relative to PDB and +40%. relative to SMOW, respectively) was maintained far from isotopic equilibrium with respect to the dissolving carbonate. The isotopic composition and Mg content of the residual solid phase was monitored throughout the approach to stoichiometric saturation. For the coralline algae Goniolithon , heterogeneous and possibly incongruent dissolution occurred which reduced the Mg / Ca mole ratio in the solid from 0.44 to 0.26. The alteration was accompanied by an apparent isotopic equilibration of up to 20% of the solid. Runs with two littoral foraminifera, Archaias and Sorites showed a decrease in the Mg / Ca mole ratio from 0.18 to 0.14 in the solid and an apparent isotopic equilibration of up to 10%. These changes began to occur before the bulk solution became saturated with respect to LMC. On the other hand the echinoid Clypeaster dissolved homogeneously and congruently with much smaller changes in magnesium and stable isotope composition: from 0.16 to 0.14 in Mg / Ca mole ratio and less than 5% apparent isotopic equilibration. All isotopic shifts were in the direction of equilibrium with the solution isotopic composition. No isotopic shifts were observed in runs with Iceland spar under identical conditions. Textural differences in microstructure discovered by SEM examination of the HMC materials used suggest the possibility of an overall textural control over the observed differences in isotopic and chemical behaviour during the dissolution runs.

Affiliated with

Also associated with

No associations

Rating

Isotopic, chemical and textural relations during the experimental alteration of biogenic high-magnesian calcite does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Isotopic, chemical and textural relations during the experimental alteration of biogenic high-magnesian calcite, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Isotopic, chemical and textural relations during the experimental alteration of biogenic high-magnesian calcite will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1102286