Use this geological calculation for a transparent first-pass interpretation of measured rock, soil, fluid, well, stratigraphic, isotopic, geophysical, or seismic data under an explicitly selected model.

Sample 143Nd/144Nd

Measured present-day 143Nd/144Nd ratio of the sample.

Sample 147Sm/144Nd

Measured 147Sm/144Nd ratio of the sample.

DM 143Nd/144Nd

Present-day 143Nd/144Nd of the depleted mantle.

DM 147Sm/144Nd

147Sm/144Nd of the depleted mantle.

Compute the single-stage Sm-Nd depleted-mantle (T_DM) model age of a sample from its Nd isotope ratios. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

T_DM (yr)

T_DM model age in years.

T_DM (Ga)

T_DM model age in billions of years.

• Radiometric ages require the correct decay constants, isotopic ratios, standards, common-component correction, closure interpretation, initial composition, and analytical uncertainties. Disturbance, inheritance, diffusion, alteration, and model choice can make a calculated number differ from the geological event age.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Compare independent measurements and models, retain units and analytical metadata, propagate uncertainty, and validate interpretations against logs, cores, maps, laboratory data, or field observations.

• Geology Sm Nd Isochron Calculator

  Fit a two-point Sm-Nd isochron and convert its slope to an age using the Sm-147 decay constant.

• Geology Stable Isotope Delta Calculator

  Convert sample and standard isotope ratios into delta notation in permil relative to the standard.

• Geologic Time Scale Lookup

  Map an age in millions of years ago (ICS boundaries) to its Phanerozoic plus Ediacaran period, era and boundary ages; boundary ages belong to the younger period.