Terre Adélie Calcite (TAC)¶

Presumably inorganic calcite formed in shallow waters offshore Antarctica. Intended as a cold, marine standard for clumped isotope measurements (Δ₄₇, Δ₄₈).

TAC-1¶

Field work (February 2026 Antarctica)¶

Carbonate crust fragments collected from a small islet offshore Terre Adélie.

Lab work (May-June 2016, LSCE)¶

Start with material in bag #2
Dried over a week in a drying oven at 40 °C
Ground using a manual coffee grinder with stainless steel burrs
Dry-sieved to a nominal fraction of 50–200 μm
Bleached overnight in a large volume of 3 % NaClOH
Rinsed at least 5 times in tap water
Final rinse in methanol over 40 μm, stainless steel sieve
Final drying overnight in drying oven at 40 °C
Total amount before distribution was 750 g

Characterization¶

Samples of TAC-1 were handed out at the 10^th International Clumped Isotope Workshop (Utrecht, Netherlands) in June 2026.

Notes¶

Contains small amounts of what looks like quartz (transparent) and goethite (dark)
Dark fragments are paramagnetic. Some/most of them were separated from TAC-1 and TAC-2 in the bleaching and rinsing steps, by repeatedly cleaning them off the magnetic bar used for stirring.

TAC-2¶

Similar material as TAC-1 above, but ground to a finer nominal granulometry of 40-50 µm. Intended for labs working with very small aliquots of carbonate.

Lab work (May-June 2016, LSCE)¶

Same starting material and processing as TAC-1, but with nominal fraction of 40–50 μm instead of 50–200 µm.
Total amount before distribution was 225 g

Characterization¶

Samples of TAC-2 were handed out at the 10^th International Clumped Isotope Workshop (Utrecht, Netherlands) in June 2026.