radiocarbon dating shells

Measuring Oxygen Isotope Ratios (δ18O) for Carbonates

Sample size recommended
Carbonates that are ready for measurement – 2 mg
For carbonates that are not ready for measurement and require pretreatment, please contact us.
Recommended container
Ziplock Bags (place in Aluminum foil if sample is small or can be crushed during shipment)
Please send your samples in small boxes instead of envelopes to protect the samples.
Turnaround time
7 business days for pretreated samples
14 business days for samples that require pretreatment in the lab
Beta Analytic offers oxygen isotope measurements for carbonates on a standalone basis, without radiocarbon dating.

Note – The laboratory also automatically includes d18O and d13C values alongside radiocarbon dating results for carbonate samples. The d18O and d13C measurements are performed simultaneously on the carbonates in an isotope ratio mass spectrometer (IRMS) at no additional cost to the client.

The interpretation of d18O values, as applied in paleotemperature studies and paleoclimate reconstructions, lies with the submitter.

Please note that the laboratory now also provides Oxygen-18 and Deuterium stable isotope measurements for water samples.

Pretreatment – It is important to understand the pretreatment applied to samples since they directly affect the final result. Contact us to discuss.

Submittal – Please use this data sheet when submitting samples for d18O analysis NOT in conjunction with C14 dating.

Please contact us at lab@radiocarbon.com if you are in doubt about the suitability or weight of your sample.

Applications of δ18O Stable Isotope Analyses

One of the major applications of d18O is in paleoclimatology – looking at oceans, glaciers and the fossils within them. The main processes that affect the Oxygen-18 (18O) / Oxygen-16 (16O) isotopic ratio are evaporation and condensation. Seawater typically has a higher 18O content than ice in glaciers.

The d18O ratio changed over time with temperature, thus measuring d18O is indicative of past climates and can differentiate between glacial and interglacial periods. During glacial periods, the oceans were enriched in 18O with the lighter 16O isotope trapped in glacial ice. The opposite was true during interglacial periods (warmer global average temperatures) when the ice melted releasing the 16O isotopes and the oceans had less 18O.

Reference:

Holli Riebeek, Paleoclimatology: the Oxygen Balance (2005), NASA Earth Observatory