Magnetic Survey, Deposit and Porphyry Outline:
Porphyry copper deposits often, but not always, appear as magnetic highs, with alteration halos usually manifested as annular (donut-shaped) or open-ring peripheral magnetic lows (Heithersay and Walshe, 1995; Ford and others, 2007). Typically, there is significant variability in magnetic susceptibility throughout the altered rock owing to the nonhomogeneity of phyllic alteration-related magnetite destruction and late-stage magnetite formation (Gettings, 2005). [Preliminary Model of Porphyry Copper Deposits, USGS – Open-File Report 2008–1321 ]
Figure 1 illustrates detailed ground magnetic intensity of the Hat Porphyry system with observed sulphide mineral occurrences. The magnetic survey has been analyzed as a part of Company’s Fresh Review of its expanded Hat Project database.
Figure 2 shows an interpretation of the magnetic signatures.
An interpretation of the semi-perfect circular magnetic features, combined with other data (resistivity, potassium distribution, sulphide occurrences) suggests that zones of sulphide mineralization are closely related to magnetic-high signatures. That data, combined with induced polarization chargeability results, guided initial drill testing that resulted in the discovery of the Lisle Zone. Further drilling has confirmed the gold – copper alkalic porphyry system proximal to the high magnetic areas. Recent geological studies that integrate property data also draw attention to areas of low magnetic intensity that help the Company focus its exploration. (Please refer to the “Target Area” section information.)