Radiometric Processing

The gamma-ray radiometric method is primarily used as a geological mapping tool. 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 the 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 visualized using ternary maps.

The extension’s menu system offers a structured workflow for processing and visualizing 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 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 account for instrument response delays.

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

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

• Remove Radon Effect
  Subtract cosmic and atmospheric radon influences.

• Compton Stripping
  Resolve overlapping spectral features between radioelements.

• Height Correction
  Correct for altitude-related signal attenuation.

• Generate Radioelement Concentrations
  Translate 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.

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

• Data files such as databases, grids, maps, voxels, geosurfaces, and 3D views

• Visualization tools like histograms and scatter plots

• Project settings, including the menus currently displayed

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

To begin working with the Radiometric Processing extension, we recommend opening a new project and then loading the menus related to the extension.

Open a New Project

1. On the Project menu select New. The New Project dialog will open.

   You can also select Create new project from the startup dialog that appears when you launch Oasis montaj.

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

3. The new project will open, enabling the main menus, toolbar icons, and the Project Explorer. These visual 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 will appear.

2. Expand the Base Menus node, select Radiometric Processing, and click OK. The menus related to the extension will now appear on the main menu bar.

The menu system is designed to provide quick access to a variety of tools and to guide you through the primary processing workflows in the extension.

Accessing Help

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

• The reference topic for the current dialog will be displayed.

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

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