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Analytical and sampling constraints in ²¹⁰Pb dating
A B MacKenzie1, S M L Hardie, J G Farmer
1Scottish Universities Environmental Research Centre, Scottish Enterprise Technology Park, East Kilbride G750QF, Scotland, UK. A.MacKenzie@suerc.gla.ac.uk
The Science of the Total Environment
|January 8, 2011
Summary
Lead-210 (²¹⁰Pb) dating using the Constant Rate of Supply (CRS) model can overestimate ages in deeper sediment cores due to data limitations. This bias increases with poorer detection limits and greater age.
Area of Science:
- Geochronology
- Environmental Science
- Radiochemistry
Background:
- Lead-210 (²¹⁰Pb) dating is crucial for establishing recent chronologies in natural deposits.
- The Constant Rate of Supply (CRS) model is widely employed for ²¹⁰Pb dating.
- Sampling and analytical limitations can impact the accuracy of the CRS model.
Purpose of the Study:
- To investigate age overestimation in deeper sediment core sections when using the CRS model.
- To analyze the influence of detection limits and core length on ²¹⁰Pb age calculations.
- To evaluate the origin and magnitude of age bias in ²¹⁰Pb dating.
Main Methods:
- Theoretical modeling of an idealized ²¹⁰Pb profile.
- Analysis of a freshwater lake sediment core using ²¹⁰Pb dating.
- Examination of the mathematical incompatibility between finite empirical data and infinite integration terms in age calculations.
Main Results:
- Finite empirical data (detection limit, core length) conflict with infinite integration terms in the CRS model.
- This incompatibility generates erroneously old ages for deeper core sections.
- Age bias escalates with decreasing detection limits and increasing age.
Conclusions:
- The CRS model, while versatile, requires careful consideration of data limitations to avoid age artifacts.
- Sampling strategies and analytical precision are critical for accurate ²¹⁰Pb dating.
- Understanding this bias is essential for reliable interpretation of sediment chronologies.
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