Posts Tagged HeliTEM

The EM Test Range in Australia

Posted by on Friday, 12 October, 2012

Southern Geoscience Consultants have released the results of the BH, ground and Airborne EM over the two, discrete and varying bedrock conductors.

The Forrestania EM Test Range is situated approximately 85km by road/track east of Hyden and ~155km by road/track SSE of Southern Cross . The test range is well positioned and provides easy access if traveling from Perth or Kalgoorlie (~4-5hrs).

The Forrestania EM Test Range has been designed to allow testing/trialling of various electromagnetic methods (surface, airborne and downhole techniques) over two, discrete and varying bedrock conductors defined during previous geophysical exploration completed on behalf of Image Resources NL. The two bedrock conductors defined and drilled by Image Resources successfully tested these targets, intersecting barren, semi-massive to massive sulphides (po-rich).
The western conductor (IR2) is of limited areal size (<75x75m), shallow depth <100m, high conductance >7000S and dips northward ~30-40 degrees. This conductor is strongly defined by surface and downhole TEM and makes for an interesting airborne TEM target.

The eastern conductor (IR4) is extensive in strike/plunge extent (~500-600m+) and reasonably well constrained in depth extent (~100-150m). The conductive source is situated at considerable depth ~300-325m (western side) to ~400m+ (eastern side), is highly conductive ~5000-10000S and dips northward ~30-40 degrees. IR4 is a more challenging conductive target for surface TEM methods with smaller transmitter loops.

The local electrical environment is characterized by the presence of a conductive overburden (~10-20S), highly resistive bedrock units and lack of any other bedrock conductors in the immediate area other than the IR2 and IR4.

  • Work Completed at the EM Test Range
    • FLTEM dB/dt and B-Field HT-SQUID coverage over the IR4 bedrock conductor with large and small transmitter loops. FLTEM dB/dt coverage over the IR2 bedrock conductor with large and small transmitter loops. Figure 1 highlights some of these results. Completed as a standard survey by Outer Rim Exploration Services.
    • MLTEM dB/dt and B-Field fluxgate coverage over the IR4 bedrock conductor (200m transmitter loops, Figure 2). – Courtesy of GEM Geophysical Surveys.
    • DHTEM dB/dt – Crone PEM surveys, holes FRC1 and FRCD3 (Figure 3). Completed as a standard survey by Outer Rim Exploration Services.
    • Fixed Loop Total Field (SAMSON) surveying – Figure 4 – courtesy of Khumsup Ltd
    • Helicopter EM surveys – HELITEM (Fugro Airborne Surveys, 2011), VTEM-max (Geotech Airborne Ltd, 2011). An example of the HELITEM and VTEM-max is shown in Figures 56 respectively. Both datasets are available through the contractors only.
    • ZTEM survey by Geotech Airborne Ltd
    • 200m modern aeromagnetic/radiometric data coverage.
  • Proposed Work to be Completed at the EM Test Range
    • MLTEM using SQUID
    • DHTEM B-Field surveying of holes FRC1 and FRCD3 (FRCD3 is now blocked).
  • Download: Figure4_Forrestania-SAMSON.pdf (222.3kb)

    Universal HTEM module from Aarhus

    Posted by on Wednesday, 3 November, 2010

    Aarhus Geophysics announces the release of a general HTEM module that allows complete advanced processing and inversion of virtually every helicopter TEM system on the market today, e.g., VTEM, AeroTEM, HeliTEM. You can now enjoy the full capability of the Aarhus Workbench software for detailed data editing, inversion to smooth and blocky models, results evaluation and display, production of final pdf maps. In true Aarhus Geophysics Aps style, the aim is to go beyond bump anomaly finding, fast approximate transforms or inversions, or any other forms of qualitative appraisal of the AEM data, and to produce quantitative results instead. The aim is to take you … from Data to Knowledge Import your AEM data in the GIS environment of the Aarhus Workbench, describing th e full System Transfer Function, and perform:

    -advanced processing of navigation, altimeters and tilt metres data

    -decoupling, filtering, and noise assessment of the EM data

    -full non linear quasi-3D spatially constrained inversion

    -constrained inversion with prior information from boreholes or other geophysics-derived layer boundary

    -results evaluation, in terms of Data Residual, Model Parameter Sensitivity, Depth of Investigation

    -model display, as horizontal maps in depth and/or elevation, and cross sections

    -custom searches of model space and thematic maps, e.g., depth to good conductor.

    2010 Frontier Exploration with airborne geophysics

    Posted by on Monday, 5 July, 2010

    Royal Roads Corp.

    The 2010 Long Range exploration program is focussed on two areas of activity, the first being the more advanced exploration on the Portage nickel discovery and the second being frontier airborne geophysics and follow-up prospecting over the newly acquired claims recently incorporated into the Long Range property. As of June 17th, 2010, the frontier airborne geophysical surveys over the newly acquired claims was completed with results anticipated to be available in August 2010.  Once received, data will be reviewed to select targets for immediate follow-up by ground prospecting. Areas surveyed by the 1,400 line kilometre Fugro HELITEM® airborne surveys include several properties underlain by unexplored gabbro bodies recently recognized to be prospective for magmatic nickel-copper sulphide deposits. Depending on results, it is hoped that the prospecting activities will help evaluate targets for further work including testing by diamond drilling.

    The Long Range property, located 64 kilometres to the southwest of Buchans, covers 381,500 hectares (381.5 km2). The exploration philosophy at Long Range is centered around the potential for discovery of a magmatic nickel sulphide deposit broadly analogous to Vale Inco’s Voisey’s Bay mine in Labrador and Kennecott’s Eagle deposit currently being developed in northern Michigan

    An airborne geophysical survey flown over the initial property in 2008 detected a number of anomalies in prospective gabbro. Follow up work ultimately resulted in the discovery of the Portage Nickel prospect and the Range Copper prospect highlighted below. Additional frontier exploration is ongoing to identify new prospects in this highly prospective and un-explored region of Newfoundland.