Calculator
Fill known REE values. Leave unknown fields blank. Use consistent units across all inputs.
Formula used
- Normalization: REEN = REEsample / REEreference
- Ce anomaly: Ce/Ce*, where Ce* = √(LaN×PrN) or (LaN+PrN)/2
- Eu anomaly: Eu/Eu*, where Eu* = √(SmN×GdN) or (SmN+GdN)/2
- Ratios: examples include LaN/YbN and NdN/YbN
- Pattern slope: linear regression of log10(REEN) against element order (La→Lu)
How to use this calculator
- Select units for your measurements (ppm or ppb).
- Choose a normalization standard, or enable custom overrides.
- Enter REE concentrations you have; blanks are allowed.
- Pick anomaly methods for Ce and Eu if needed.
- Press Submit to view metrics, plot, and the normalized table.
- Use Download buttons to export your computed results.
Example data table
Example concentrations in ppm for demonstration. Use “Load example values” in the form to populate inputs instantly.
| Element | Example (ppm) |
|---|---|
| La | 10.5000 |
| Ce | 22.3000 |
| Pr | 2.9000 |
| Nd | 12.7000 |
| Sm | 3.4000 |
| Eu | 1.1000 |
| Gd | 3.7000 |
| Tb | 0.6000 |
| Dy | 3.6000 |
| Ho | 0.7500 |
| Er | 2.1000 |
| Tm | 0.3100 |
| Yb | 2.0000 |
| Lu | 0.3100 |
Why REE patterns are normalized
Rare earth elements behave coherently during melting, crystallization, and fluid–rock interaction, but their absolute abundances vary widely between samples. Normalization divides each measured concentration by a chosen reference value, producing dimensionless REE_N values that highlight subtle fractionation. A smooth pattern can reveal source composition, while kinks often indicate mineral control, redox effects, or analytical issues.
Selecting a normalization reference
This calculator offers common references such as CI chondrite and PAAS, plus optional custom overrides. The reference acts as the baseline curve, so choose one that matches your comparison set and reporting convention. For igneous rocks, CI-based normalization is often used to compare mantle-derived signatures, while PAAS can be useful for sedimentary or crustal contexts. Consistency matters more than the “best” choice. When using custom normalizers, enter values in ppm and cite the dataset. If inputs are in ppb, they are converted to ppm internally, so normalization and totals remain comparable across samples and reporting workflows.
Ce and Eu anomaly calculations
Cerium and europium can deviate from neighboring REE because they change oxidation state under certain conditions. The tool estimates Ce* from La_N and Pr_N, and Eu* from Sm_N and Gd_N, using either geometric or arithmetic means. Ce/Ce* < 1 can suggest oxidative scavenging or seawater influence, whereas Eu/Eu* > 1 may reflect plagioclase accumulation or a reduced source where Eu2+ is stabilized.
Ratios and pattern slope for interpretation
To summarize fractionation, the calculator reports ratios like La_N/Yb_N and Nd_N/Yb_N, which compare light to heavy REE enrichment. It also computes a linear regression slope of log10(REE_N) versus element order (La→Lu). Positive slopes indicate LREE enrichment relative to HREE, while near-zero slopes imply flatter patterns. Always examine the full curve before relying on single-number metrics.
Reporting, exports, and quality checks
Results are displayed above the input form for quick iteration, with a plotted curve and a normalized table. Exporting to CSV preserves values for spreadsheets, while the PDF provides a compact report for lab notebooks. If the pattern shows spikes, re-check units, detection limits, and whether non-positive values were entered. Comparing replicate analyses and reporting the chosen reference improve reproducibility across studies.
FAQs
What does normalization mean in this tool?
Normalization divides your sample concentration by the selected reference value for that element. It converts ppm or ppb inputs into dimensionless REE_N numbers that emphasize pattern shape rather than absolute abundance.
Which reference should I choose: CI or PAAS?
Pick the reference that matches your field’s convention and comparison dataset. CI-based references are common for mantle and igneous studies, while PAAS is often used in sedimentary or crustal work. Consistency across samples is essential.
Why are Ce and Eu anomalies important?
Ce and Eu can change oxidation state, so they may depart from neighboring REE. Ce/Ce* and Eu/Eu* quantify those departures using interpolated Ce* and Eu* values, helping you screen for redox effects or plagioclase control.
Can I leave some elements blank?
Yes. The calculator can handle missing elements, but patterns and slopes are more reliable when you provide most of La–Lu. Enter at least three values to compute a meaningful curve and summary metrics.
Why does the plot skip some points?
Log plots require positive normalized values. If an element is blank, zero, or negative, the point is omitted to avoid invalid math. Check units and detection limits when many points are missing.
How are CSV and PDF exports generated?
CSV exports include metrics and the full element table for spreadsheet analysis. The PDF is a compact, single-page report suitable for sharing or archiving alongside sample metadata and lab notes.