Geology Rb Sr Initial Ratio Calculator
Declared closed-system initial87Sr/86Srat independently established age, subtract87Rb/86Sr(expλt−1). Not fit isochron age, initial reservoir or open-system correction; negative inferred residual retained for inconsistent data.
Description
An initial rubidium–strontium ratio corrects the observed strontium ratio for adopted radiogenic growth.
An initial rubidium–strontium ratio corrects the observed strontium ratio for adopted radiogenic growth.1
The age and decay constant are independently supplied model assumptions. Use this tool to calculate the stated observation or conditional model from supplied measurements.
When to use Geology Rb Sr Initial Ratio Calculator
Use this tool to calculate the stated observation or conditional model from supplied measurements. Establish the sample and coordinate basis, matching units, calibration source and applicable model assumptions.
How to use Geology Rb Sr Initial Ratio Calculator and understand its results
- Establish the sample and coordinate basis, matching units, calibration source and applicable model assumptions.
- Enter actualSr87Sr86Ratio, actualRb87Sr86Ratio, callerIndependentlyEstablishedAgeYears, callerVerifiedRb87DecayConstantPerYear, using the field meanings and rules below, then run the tool.
- Read result.conditionalInitialSr87Sr86Ratio. Interpret each field using the units, signs and evidence rules below.
- If input validation fails, correct the reported field and run again. Before applying a successful result, check the stated reference scope, units, assumptions and any retained unknown evidence.
| Input field | Meaning | Value type | Requirement |
|---|---|---|---|
| actualSr87Sr86Ratio | Actual sr87 sr86 ratio | number | Required |
| actualRb87Sr86Ratio | Actual rb87 sr86 ratio | number | Required |
| callerIndependentlyEstablishedAgeYears | Caller independently established age years | number | Required |
| callerVerifiedRb87DecayConstantPerYear | Caller verified rb87 decay constant per year | number | Required |
Require nonnegative observed Sr87/Sr86, Rb87/Sr86 and age years, with positive supplied Rb87 decay constant per year. Subtract Rb ratio times expm1(lambda×age) from observed Sr ratio. Negative inferred initial ratios are retained rather than clamped. Nonfinite results fail; no isochron fit or age determination is performed.
initialSrRatio=observedSrRatio−RbRatio×expm1(lambdaPerYear×ageYears) Apply the field units and exact ordering, boundary and evidence rules above.
| Output field | Meaning | Value type |
|---|---|---|
| result | Structured result containing the calculation or selected reference fields below | object |
| result.conditionalInitialSr87Sr86Ratio | Conditional Initial Sr87 Sr86 Ratio; use the units, sign convention and calculation stated above | number |
{
"input": {
"actualSr87Sr86Ratio": 0.8,
"actualRb87Sr86Ratio": 0.1,
"callerIndependentlyEstablishedAgeYears": 1,
"callerVerifiedRb87DecayConstantPerYear": 0.6931471805599453
},
"output": {
"result": {
"conditionalInitialSr87Sr86Ratio": 0.7000000000000001
}
}
}Limitations and assumptions
The age and decay constant are independently supplied model assumptions. Results depend on the independently established measurement basis and the exact model assumptions above.
Every listed input requires an explicit value. Unexpected fields, incorrect value types, nonfinite numbers and sparse numeric arrays fail validation; tool-specific bounds and alignment rules apply as described above. Extremely large inputs or outputs can also be rejected. An input error is distinct from a successful calculation that reports a false comparison or retains unknown evidence.
Alternative or Complementary methods
Use Geology Zircon Age Calculator to examine a related aspect: Zircon age interpretation requires an applicable isotope system and age model.
Use Geology Crustal Residence Time Calculator where its separate inputs and scope apply: Crustal residence time depends on an adopted isotope-reservoir evolution model.
References
-
Geology Rb Sr Initial Ratio Calculator — tool.io
Similar or alternative tools
- Geology Zircon Age Calculator
Zircon age interpretation requires an applicable isotope system and age model.
- Geology Crustal Residence Time Calculator
Crustal residence time depends on an adopted isotope-reservoir evolution model.