U-Th Dating – Sample Types and Selection

The following sample size recommendations are general guidelines. Please contact us if you are concerned that your samples are too small.

Reminders:

  • Do not leach samples for cleaning, even with weak acid, as leaching has been shown to significantly affect the uranium concentration in the sample, leading to erroneous ages.
  • DO NOT wrap samples in aluminum or any metal foil. Use weighing paper if you need to wrap them.
  • Submit samples in a ziplock bag or teflon container with PRINTED SAMPLE ID attached outside the bag.

Always choose the best samples for your research objectives

Our recommended sample sizes assume the material is dry and free of adhering matrix.

Please tap/click on a row to view the sample preparation instructions for each material.

Material Type Sample Size Recommended Container Other Isobar Services Available
Bone, Tooth, Shell 100-150 mg
  • Plastic or glass vials
    Put them inside a labeled Ziplock bag.
Boron Isotopes,
Lead Isotopes,
Sr Isotope Analysis		 +
The laboratory is able to conduct U-Th on these sample types, however, since they are considered an open system with respect to uranium and thorium, they may yield aberrant ages.
Coral 30-50 mg
  • Glass or plastic vials
 Boron Isotopes
Sr Isotope Analysis		 +
For the best results, make sure your samples are clean and free from clay particles and other detritus.

It is highly recommended to check the mineralogy of your sample. Choose samples with the highest amount of aragonite.

Homogenize your samples, preferably using an agate mortar and pestle, and transfer into plastic or glass vials. Homogenized samples are digested in 6 M nitric acid (lower concentrations may be used if the sample contains clay and detritus).
Stalagmite and Flowstone 100-150 mg
  • Glass or plastic vials
None at this time +
Homogenize your samples, preferably using an agate mortar and pestle, and transfer into plastic or glass vials. Homogenized samples are digested in 6 M nitric acid.

NOTES:

  • All samples will be screened for U and excess Th prior to isotope dilution and extraction chromatography processes for purification and measurement. Only samples with acceptable ranges of Th will be selected for analysis. If a sample is considered not suitable for analysis, the client will only be charged for the screening.
  • Samples that did not remain closed with respect to U and Th isotopes will yield ages that may not fit in with established chronologies.
  • We utilize an analytical method which provides precise measurement of 233U-234U-235U-236U-238U-229Th-230Th-232Th with high resolution whether a sample remained closed with respect to U and Th or displays open system behavior.

Please consult the lab before submitting samples.

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Duration: 2 minutes, 30 seconds || Speaker: Maren Pauly, PhD
This video excerpt is part of Isobar Science’s webinar: An Introduction to Uranium-Thorium Dating.
Disclaimer: This video is hosted in a third-party site and may contain advertising.