Generate Radioelement Ratios

Use the RPS > Generate Radioelement Ratios option (geogxnet.dll(Geosoft.GX.Radiometrics.GenerateRadioelementRatios;Run)*) to calculate standard ratios such as U/Th, U/K, and Th/K. These ratios are commonly used for final map presentation and for identifying subtle, geologically significant features in the data.

You can apply thresholding to exclude very low denominator values. Additionally, low-pass filters can be applied to smooth noisy data.

Generate Radioelement Ratios dialog options

Input channel suffix	If Generate Radioelement Concentrations has been run on the current database, the suffix for the generated channels is automatically detected and preselected. If multiple sets exist, all suffixes are listed, with the most recent one selected by default. Once a suffix is chosen, the associated channels are listed below the field. Script Parameter: SPECTRO.GENERATE_RADIOELEMENT_RATIOS_INPUT_SUFFIX
Minimum Concentrations Specify the minimum concentration thresholds for each radioelement. These values help prevent division by very low denominators during ratio calculations. See the Application Notes for more details.
Threshold method	Choose a method for handling values below the minimum concentration: Clip (Default): Values below the specified minimum concentration are set to the minimum value. Dummy: Values below the minimum concentration are replaced with placeholder (dummy) values. Script Parameter: SPECTRO.RMETHOD [0: Clip; 1: Dummy]
Potassium (K) in %	Enter the minimum concentration value for Potassium (K), expressed as a percentage (%). Default: 1 Script Parameter: SPECTRO.KMIN
Uranium (U) in eU ppm	Enter the minimum concentration value for Uranium (U), expressed in equivalent uranium parts per million (eU ppm). Default: 1 Script Parameter: SPECTRO.UMIN
Thorium (Th) in eTh ppm	Enter the minimum concentration value for Thorium (Th), expressed in equivalent thorium parts per million (eTh ppm). Default: 1 Script Parameter: SPECTRO.THMIN
Low-Pass Filter Cutoffs Specify the cutoff values for low-pass filtering to smooth noisy data. These filters reduce statistical noise, particularly in areas with low count rates. To disable filtering for a specific channel, set its cutoff value to 0. See the Application Notes for more details.
Potassium (K)	Enter the cutoff value for low-pass filtering Potassium (K) data. Default: 25 Script Parameter: SPECTRO.KRATIOSW
Uranium (U)	Enter the cutoff value for low-pass filtering Uranium (U) data. Default: 25 Script Parameter: SPECTRO.URATIOSW
Thorium (Th)	Enter the cutoff value for low-pass filtering Thorium (Th) data. Default: 25 Script Parameter: SPECTRO.THRATIOSW
Output Channel Names The calculated ratios will be stored in the corresponding output channels in your database.
Uranium / Thorium	Specify the output channel for the Uranium-to-Thorium ratio. Default: UTh Script Parameter: SPECTRO.UTHRAT
Uranium / Potassium	Specify the output channel for the Uranium-to-Potassium ratio. Default: UK Script Parameter: SPECTRO.UKRAT
Thorium / Potassium	Specify the output channel for the Thorium-to-Potassium ratio. Default: ThK Script Parameter: SPECTRO.THKRAT

Application Notes

Calculating U/Th, U/K, and Th/K Ratios

When calculating radiometric ratios, two key challenges must be addressed:

• Avoiding zero values in the denominator

• Extracting meaningful ratios from areas with low count rates

Handling Zero Denominators

The tool offers two methods to manage zero denominator issues:

1. Dummy Values: Inserts placeholder values to indicate that certain data should not be processed. This method is advantageous because the system interpolates smoothly across dummy values using adjacent data.

2. Minimum Thresholding: Sets values below a defined threshold to a specified minimum concentration, ensuring that the denominator remains valid.

Managing Low Count Rate Data

Low count rate regions tend to have higher statistical errors. To address this, the tool applies a low-pass filter to smooth the data. This technique is based on the principle that smoother input yields smoother output.

Choosing Minimum Concentration Cutoff Levels

To determine appropriate minimum cutoff values:

• Examine the concentration data (in the channels generated through Generate Radioelement Concentrations) on lines flown over water where no ground-based radiation is expected.

• Ideally, these readings should be zero, allowing you to set the cutoff at zero.

• If the data is not zero, select cutoff values based on the lowest reliable concentration levels observed for each channel.

Choosing Filter Cutoff Levels

To determine appropriate filter cutoff values:

• Review the concentration data for each channel.

• Look at the profile view to identify visible noise and choose a cutoff value that effectively reduces this noise without distorting the underlying signal.

• If you want to keep a channel unfiltered, set its cutoff value to 0.