Radiometric Processing

The gamma-ray radiometric method is primarily used for geological mapping. Broad changes in lithology or soil type often correspond to significant shifts in the concentrations of naturally occurring radioelements. Smaller variations may indicate weathering, alteration, or mineralization, making this method effective for mineral deposit detection.

One key application is the identification of potassium alteration, commonly associated with hydrothermal ore deposits such as gold, tin, and tungsten. Additional uses include uranium and thorium exploration, heat-flow studies, and environmental mapping, such as delineating surface drainage features.

The goal of processing gamma-ray spectrometric data is to derive the concentrations of the three primary radioelements—Potassium (K), Uranium (U), and Thorium (Th)—as if measured directly on the ground. These concentrations are then visualised using ternary maps.

The extension’s menu system offers a structured workflow for processing and visualising radiometric data. It guides you through tasks such as smoothing spectral data, extracting region-of-interest (ROI) windows, applying correction parameters, deriving radioelement concentrations, and displaying concentration ratios on ternary maps.

• Smooth Spectra
  Apply noise-adjusted singular value decomposition (NASVD) to suppress statistical noise.

• Generate Radioelement Counts
  Define energy windows for key radiometric elements.

• Calculate STP Elevation
  Normalize data to standard environmental conditions.

• Account for Dead Time
  Adjust raw data to compensate for instrument response delays.

• Along-Line Filtering
  Apply low-pass filtering to airborne radiometric data.

• Remove Aircraft and Cosmic Effects
  Remove contributions from the aircraft and ambient background radiation.

• Remove Radon Effect
  Subtract atmospheric radon and residual background influences.

• Compton Stripping
  Resolve overlapping spectral features between radioelements.

• Height Correction
  Correct for signal attenuation due to altitude.

• Generate Radioelement Concentrations
  Convert spectral counts into radioelement concentration values.

• Generate Radioelement Ratios
  Compute ratios between K, U, and Th concentrations.

• Ternary Map Generation
  Visualise the spatial distribution of radioelement concentrations.

• Compress Energy Spectrum
  Reduce the size of a radiometric energy spectrum by compressing it into fewer windows.

• View Coincident Arrays
  Display up to three coincident array channels to compare spectral radiometric data.

Open a New Project

Working in Oasis montaj requires a project file (*.gpf). A project encompasses all items in your workspace, including:

• Data files (for example, databases, grids, maps, voxels, geosurfaces, and 3D views)

• Visualization tools (for example, histograms and scatter plots)

• Project settings, including the menus currently displayed

This structure ensures that your entire working environment is saved and can be easily restored.

To begin working with the Radiometric Processing extension, open a new project and then load the corresponding menus.

1. On the Project menu, click New. The New Project dialog opens.

   Alternatively, select Create new project from the startup dialog when you launch Oasis montaj.

2. In the New Project dialog, specify the name and location for your project file (*.gpf), then click Save.

3. The new project opens, enabling the main menus, toolbar icons, and the Project Explorer. These indicators confirm that the system is ready for use.

Load the Menus

1. On the Project menu, select Manage Menus, or click the Manage Menus icon on the Project Explorer toolbar. The Manage Menus dialog opens.

2. In the Base Menus node, expand Radiometric Processing, select the relevant entries, and click OK. The related menus are added to the main menu bar.

The menu system provides quick access to a variety of tools and guides you through key processing and interpretation workflows.

Accessing Help

Once the Radiometric Processing (RPS) menus are loaded, click the Help button in any dialog opened from these menu items:

• The reference topic for the current dialog is displayed.

• Use the Help Topics tab to navigate to other topics of interest.

• Use the Search tab to find specific topics by entering keywords.