The Sams Creek porphyry gold deposit, Northwest Nelson, New Zealand

摘要

Sams Creek mineralisation is contained within a hydrothermally altered peralkaline granite porphyry dyke that intrudes Early Paleozoic metasediments (Tulloch 1992). The dyke is up to 60m thick and can be traced for over 7km along strike. The dyke generally dips steeply to the north (~600) with gold mineralisation extending down dip for at least 1km and is open at depth. A resource of 1.0Moz of gold has been estimated at the Main Zone (Golders 2012) which comprises an 800m section of the Sams Creek Dyke, highlighting the potential for a significant increase in the known gold resource.The porphyry dyke is variably mineralised and has been modified by at least four alteration / mineralisation phases. The first stage of alteration (Stage I) is represented by a magnetite- ankerite±biotite assemblage (Fig. 1a). The occurrence of the early stage alteration minerals, magnetite and biotite, is similar to the magnetite + biotite alteration found in many calc- alkaline and alkaline porphyry Cu-Mo-Au deposits, where it represents an early high temperature stage (Brathwaite & Faure 2004).