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The ZTEM Survey Discovery of the Balboa Cu-Mo-Au Porphyry at Cobre Panama
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, EAGE/DGG Workshop on Deep Mineral Exploration, Mar 2016, Volume 2016, p.1 - 5
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Abstract
The ZTEM natural field helicopter EM discovery of the Balboa Cu-Mo-Au porphyry, Panama, in 2010 is discussed. Balboa is the most recent of six copper deposits discovered at Cobre Panama since 1966 but had escaped detection by soil geochemistry and drilling due to burial below thick, conductive saprolite. The survey consisted of 831 line-km of ZTEM (z-axis tipper electromagnetics) and aeromagnetics, flown at 300 metre line-spacings. The ZTEM results mapped elevated conductivity closely associated with all the known porphyry orebodies and Balboa represented a similar, untested feature. Balboa’s magnetic response was inconclusive due to lack of a similar magnetic low. Drill testing encountered mineralization, 60 m below surface, and led to the discovery of the Balboa orebody within 3 months of the ZTEM survey. 2D inversion results show the ZTEM conductor correlates directly with the higher grade zone, both spatially and at depth. A 2D synthetic model predicts that Balboa is potentially detectable below 750 metres of cover. Balboa is the first documented case of a porphyry copper discovery using ZTEM airborne electromagnetics.