Module 6: ReSources Full example

Training Objectives

By the end of this session, you will:

1. Set up & run a complex mixing model in ReSources
2. Interpret different estimate types (source contributions, by-proxy, components)
3. Cover the final step in the isotope-to-chronology pipeline: taking the marine dietary carbon estimate produced by ReSources and using it to apply a mixed-curve calibration in OxCal, so that each individual’s radiocarbon date accounts for their personal dietary reservoir offset.

Pre-Analysis Checklist

Add the mean δ¹³C+sd & mean δ¹⁵N+sd you have calculated to source_data (worksheet) york.xlsx

The source_isotopic (worksheet) will automatically update with the estimated actual δ¹³C and δ¹⁵N of protein and energy components ingested from measure collagen using offsets detailed below.

Resources Model options

Navigate to: Model Options

Resources Options

Driffield Terrace, York: Results

Complete the following on your own once ReSources has finished running the model:

• [1] Plot the Marine Fish (MF) estimate of the Target Data and save as an SVG file
• [2] Plot the protein estimate the Target Data and save as a PDF file
• [3] Plot the carbs/lipids estimate of males/females and save as a png file
• [4] Export the summary statistics
• [5] Plot the estimates of all source contributions for DRIF-10

DRIF-10 has a potentially significant marine fish caloric contribution to their diet

The Marine Dietary Reservoir Effect

The Two-Step Solution

ReSources and OxCal handle this together — but each does a distinct job:

Step 1: ReSources

OxCal code export

Output>OxCal export

Estimate 1 = Source contributions_MF

For the Mean Detla R 1 and SD Delta R 1 you need to calculate the local correction: ΔR

The global marine reservoir correction (~400 ¹⁴C yr) is built into the Marine20 calibration curve. ΔR captures the additional local offset specific to your coastal region and time period. It must be determined separately — see the Marine Reservoir Database at calib.org/marine/

Get data from

• [1] 20 Nearest point
• [2] 53.951261 centered @ lat
• [2] -1.0982037 centered @ long

Select all and Calculate Average of ticked boxes

Weighted mean ΔR = -140 Uncertainity ΔR = 55

Populate Mean Detla R 1 and SD Delta R 1

Click Type of estimate Mean + SD

Generate OxCal code

Step 2 Generate OxCal code

Mean + SD of marine fish estimate

Step 2 Generate OxCal code

PDF of marine fish estimate

The OxCal Code — Step by Step

Plot()
 {
  // Step 1: Declare both calibration curves
  Curve("IntCal20", "IntCal20.14c");
  Curve("Marine20", "Marine20.14c");
  // Step 2: Define local marine reservoir offset (ΔR ± error, in 14C years)
  //         Obtain from calib.org/marine/ for your site location and period
  Delta_R("LocalMarine", -140, 55);
  // Step 3: One Mix_Curve + R_Date pair per individual
  //         Mix_Curve("label", "terrestrial curve", "marine curve", %marine mean, %marine SD)
  Mix_Curve("Diet_DRIF-10",  "IntCal20", "LocalMarine", 10, 6);
  R_Date("DRIF-10_corrected",  1755, 30);
  Curve("IntCal20");
  R_Date("DRIF-10",  1755, 30);
 };