Helicopter-borne Z-Axis Tipper Electromagnetic (ZTEM) and Aeromagnetic Survey, Mt. Milligan Test Block (NTS 93N, 93O)
- Geotech Limited

Mt Milligan Test Block ZTEM (Z‐Tipper Axis Electromagnetic) surveys were conducted over the Mt‐Milligan Test Block, belonging to Terrane Metals Corp. (Vancouver, BC) and situated in the Mackenzie region of central British‐Columbia, from October 15TH to 22ND, 2008. The ZTEM survey comprised airborne Tipper AFMAG (audio frequency electromagnetics) measurements, as well as aeromagnetics using a caesium magnetometer. The survey consisted of twenty five (25) approx. 8.0 km long, EW oriented flight lines, totaling 200 line‐km, that were obtained at nominal 250m line spacings over an approximately 6 x 8 km area. The area was chosen because it hosts the Mt Milligan copper‐gold porphyry deposit, containing a Measured and Indicated Mineral Resource of 590.8 Mt at 0.193% Cu and 0.352 g/t Au, totaling 2.52 billion lb copper and 6.70 million oz gold (Terrane Metals Corp. 2008), that is not yet in production, and also because area's geology is well known and available in the public domain ‐ making it an ideal case‐history example.

The Z‐axis tipper measurements of the vertical (Z) component were obtained using Geotech's patented ZTEM induction aircoil system, suspended at approximately 110m elevation above ground level. The vertical component data (Hz) were then ratioed to fixed horizontal field measurements (Hx‐Hy) obtained using identical reference coils, that were oriented in the in‐line (X) and cross‐line (Y) directions, in order to obtain the tipper functions Z/X and Z/Y. The In‐Phase and Quadrature components ZTEM field ratio data were obtained, using Fourier‐based, digital signal processing analyses, at 5 frequencies, between 30Hz and 360Hz. The magnetometer was a Geometrics proton‐precession model towed at 130m above ground level.

Final Deliverables
Geoscience BC Report 2009-7
Helicopter-borne Z-Axis Tipper Electromagnetic (ZTEM) and Aeromagnetic Survey, Mt. Milligan Test Block

Z-TEM (Z-Axis Tipper Electromagnetic System) is a passive airborne electromagnetic system, which uses the natural time varying changes in the earth's magnetic field to detect conductors, map geology and explore for large poorly conductive features such as regional faults and porphyry copper deposits. Geoscience BC and Terrane Metals Corp partnered on this Z-TEM survey of the Mt Milligan property. The report is composed of two short summaries on the survey and a set of pdf maps. The data is provided in geosoft format.  



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