Open Access
Subscription Access
Open Access
Subscription Access
Stable Carbon and Oxygen Isotope Analysis of Natural Calcite and Dolomite Mixtures using Selective Acid Extraction
Subscribe/Renew Journal
Accurate analysis of coexisting calcite and dolomite for δ13C and δ18O is generally hindered by the difficulty in the physical separation of these minerals. The difference in the reaction rates of calcite and dolomite with phosphoric acid, has been used to chemically separate these carbonates. Previously established procedures are only suitable for samples containing 1:1 calcite-dolomite pairs. However, these are sometimes tedious and time-consuming. Using mixtures of calcite and dolomite, two different selective acid extraction procedures (for reactions at 25°C), one for calcite-rich and the other for dolomite-rich carbonates, have been developed. Reduction of grain size (to 37μm - 45μm) increased the reaction rate and hence decreased the total reaction time to a reasonable interval (≤72 hours for dolomite). Applying these procedures, δ13C and δ18O of calcite and dolomite/ankerite of carbonatites from Amba Dongar and Sung Valley carbonatite complexes of India were measured and their temperatures of crystallization determined. Accurate isotopic compositions of individual carbonates of calcite-dolomite mixtures can be determined for geological interpretations by these procedures.
Keywords
Stable Isotopes, Carbonate Mixtures, CO2 Extraction Technique, Calcite, Dolomite, Ankerite, Carbonatite, Amba Dongar, Sung Valley.
Subscription
Login to verify subscription
User
Font Size
Information
Abstract Views: 173
PDF Views: 2