HELICOPTER MAGNETICS AND RADIOMETRICS

XPlorer™ gradiometer systems utilise dedicated low-noise aircraft, non-magnetic composite horizontal-boom mountings, high speed synchronous data sampling and gradient sensor configurations.

Employing dedicated powerful ASTAR B-series helicopters as a platform, XPlorer™ systems are able to maintain a tight drape with low survey height essential for collecting quality high resolution data. The Xplorer™ system has proven robust and delivered consistently.

NEW RESOLUTION MAGNETICS

Aeromagnetic data is used routinely in most exploration environments to provide essential lithological and structural mapping. Mineralisation is often hosted in complex geological environments and projects benefit significantly from collection of high resolution magnetic data. As magnetic anomalies decay exponentially with distance from source, low survey height is a key component to data quality and encourages the use of helicopter platforms which are also ideal in environments with rugged topography.

Low survey height results in a dramatic improvement in high frequency content:

• More structural and textural information
• Better gradient enhancement
• Improved anomaly definition

Gradient enhanced products improve:

• Spatial positioning of anomalies
• Resolution of line parallel features
• Overall resolution – equivalent to flying at tighter line spacing

High speed data sampling of magnetic (20 Hz) and DGPS (10 Hz) data improves:

• Definition of short-wavelength anomalies

NEW RESOLUTION RADIOMETRICS

Aerial gamma-ray surveying reflects geochemical variations of potassium, uranium and thorium in the upper 30 cm of the Earth’s surface. Radiometric surveying thus provides a powerful and cost effective means of mapping outcropping and subcropping geology. In addition to basic lithological information, radiometric data is used directly to map alteration zones (e.g. porphyry copper and shear zone hosted gold); identify surficial extent of uranium mineralisation; and prioritise and discriminate Fe-oxide-Cu-Au, granophile deposits and mafic targets.

Legislation requiring radiation pollution monitoring for the mining industry is becoming a standard in many countries. This is an ideal application for ultra-high resolution radiometric survey.

As part of the XPlorer™ package, NRG™ offers high resolution, full-spectrum radiometric data as a complement to its industry-leading gradient enhanced magnetic data. The reduced survey height offered by a helicopter platform significantly improves signal to noise ratio; which in turn enables a higher sampling rate of 2 Hz (which can be further increased for ultra-high resolution survey). This, coupled with slower survey speed, results in a down-line sample window of approximately 20 m which is a three-fold improvement on standard fixed-wing systems. Up to 2048 in³ NaI crystal pack is employed with full spectrum recorded using industry-leading Radiation Solutions spectrometers. Full spectral NASVD processing is applied to all data as a standard.

NEW RESOLUTION DATA ACQUISITION AND EQUIPMENT SPECIFICATION

Custom designed and built, the NRG™ data acquisition system is at the core of the XPlorer™ system. Synchronous, high speed sampling (> 1,000 Hz) is controlled using a Rb atomic clock. The high sample rates allow for intelligent down-sampling of magnetic data to a 20 Hz base frequency which results in an extremely low noise envelope. Similarly, sample rates of ancillary and GPS data are increased. Flight steering and real-time QC is achieved through a GUI interface for safe pilot-only operation.

TECHNICAL SPECIFICATIONS