Description
Reconstruct the sample ratio from first delta and reference, divide by the second reference, subtract one, and multiply by 1000.
An isotope ratio depends on which isotope is in the numerator and denominator. Delta notation compares a ratio with a reference on a per-mil scale, while mixing and decay models require explicit amount and system assumptions.
Reconstruct the sample ratio from first delta and reference, divide by the second reference, subtract one, and multiply by 1000.
When to use this tool
Use Isotope Reference Delta Offset when you need a stated isotope-reference, mixing, or one-step decay calculation.
How to use the tool and how it works
- Enter firstDelta, firstReferenceRatio, secondReferenceRatio. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read secondDelta. Use the output convention below.
Require firstDelta at least -1000 and positive firstReferenceRatio and secondReferenceRatio. Reconstruct the sample ratio from first delta and reference, divide by the second reference, subtract one, and multiply by 1000.1
Changing an isotope delta reference requires reconstructing the ratio before renormalizing; simply subtracting two reference labels does not perform that conversion.2
| Input field | Meaning and units | Accepted input |
|---|---|---|
| firstDelta | First Delta | Required. Finite number; minimum -1000. |
| firstReferenceRatio | First Reference Ratio Unit: 1. | Required. Finite number; strictly above 0. |
| secondReferenceRatio | Second Reference Ratio Unit: 1. | Required. Finite number; strictly above 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| secondDelta | Second Delta | Required. Finite number. |
{
"input": {
"firstDelta": 0,
"firstReferenceRatio": 2,
"secondReferenceRatio": 1
},
"output": {
"secondDelta": 1000
}
}Limitations and assumptions
- Both references must describe the same isotope-ratio orientation; delta values are per mil. This changes the reference normalization, not the measured isotope composition or instrumental calibration.
- Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Use the appropriate reference materials and full isotope model for interpretation. Preserve ratio orientation, reference scale, denominator-isotope weighting, uncertainty, and any open-system or fractionation effects.
References
-
Calculation and input contract: geochemistry/isotope-reference-delta-offset — tool.io
-
Fundamentals of Isotope Geochemistry: delta notation — USGS, Kendall and Caldwell
Similar or alternative tools
- Isotope Delta To Ratio Standard Term
Return sampleRatio equal to standardRatio times (1+deltaPerMil/1000).
- Isotope Standard Delta Residual
Compute delta as 1000 times (sample ratio divided by standard ratio minus one), then return reported minus derived delta as the residual.