Passive and active helicopter EM survey comparisons over the 501 Project Cu-Zn volcanogenic massive sulphide at McFauld's Lake, northern Ontario

Abstract

The 501 project is a high grade Zn-Cu-Pb-Ag mineralized, Mattagami-Noranda style volcanogenic massive sulphide deposit that is situated in the Ring of Fire region of McFauld's Lake in Ontario. It hosts significant intersections of massive and semi-massive sulphide which have been delineated over a north-south strike length of 200m and to a vertical depth of 275m from surface. The 501 zone was discovered in 2008 following drilling of AeroTEM airborne electromagnetic and follow-up ground magnetic and horizontal loop HLEM survey program in 2007. In fall 2008, the deposit and surrounding area were reflown with the VTEM helicopter EM system. And in summer 2009, the area was flown with the ZTEM passive helicopter EM system. The objectives of the VTEM survey was to provide greater depth of investigation, below the conductive alluvial and sedimentary cover, and for the ZTEM survey to provide indications of possible extensions of mineralized zones at depth. Airborne EM, both passive and active, are known to be very useful tools for copper exploration â?? albeit respectively for disseminated copper porphyries and Cu-bearing volcanogenic & magmatic massive deposits Although, in exploration settings, passive and active AEM surveys are rarely both flown over the same property, several joint ZTEM-VTEM test case studies for massive sulphides have been presented, notably the Axis Lake, Eagle's Nest, Nebo-Babel, Forrestania and Mayville magmatic Cu-Ni deposits, as well as the Lalor Lake Cu-Au VMS deposit. However, in nearly all instances these have all been relatively large/long strike-length orebodies, which are well-suited to ZTEM's large footprint and large depth of penetration. However, at approximately 200x 250m, the 501 zone is a relatively small VMS deposit that appears to respond well to all three active and passive airborne EM systems that have surveyed the property. .