26 Impact Minerals Ltd Annual Report 2022 6.3 THE IMPORTANCE OF FEEDER ZONES Recently published scientific work, and by the CSIRO in particular, has shown that many chonoliths and other steeply dipping mafic-ultramafic intrusions that host significant massive sulphide deposits, commonly have mineralisation within conduits that act as feeder zones to the entire intrusive complex. These feeder zones are priority target areas because the research work has also shown that within intrusions with strong vertical magma flow, massive sulphides are often deposited as the magma slows its ascent and drains back down into the main conduit. This “back flow” can cause deposition of massive sulphides in the feeder zone as proposed in a very elegant model for chonolith development developed by Professor Steve Barnes and co-workers at CSIRO (Figure 6.5). Impact has been using this model to help drive its exploration programme at Broken Hill (ASX Release 21st January 2021). Accordingly, the Company views the new conductor identified by IGO as a compelling target. Review of Operations continued Figure 6.5: Model for the formation of nickel-copper-PGM deposits within evolving magma conduits including chonoliths. Note the massive sulphide within the feeder zones/conduit necks (from Barnes, S.J. et al. Ore Geology Reviews Volume 76, July 2016, Pages 296-316)
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