High positive anomalism in Central Otago, New Zealand airborne magnetic field data correlates with the distribution of magnetite bearing/rich mafic schist, magnetite-bearing peak metamorphic/metasomatic quartz veining and locally enclosed magnetite-rich cherts. Magnetite destruction, defining relatively young, local and regional scale faulting has been effected by low temperature, structurally controlled hydrothermal alteration resulting in pervasive Fe-rich carbonate formed after chlorite and Fe-sulphides replacing magnetite.
Left. Metamorphic/metasomatic magnetite bearing chlorite, epidote and actinolite/tremolite-rich mafic schist and contained peak metamorphic quartz veining.
Above. Magnetite mutually intergrown with peak metamorphic chlorite, amphibole and epidote. 600 microns field of view. ppl/rl.
Above. Pyrite formed after metamorphic /metasomatic magnetite enclosed by Fe-carbonate after chlorite of mafic schist. 600 microns field of view. ppl/rl.
Right. Hydrothermal carbonate altered mafic schist host to pseudomorphed and partly preserved peak metamorphic/ metasomatic magnetite enclosed by metasomatic Fe-rich carbonate replacing mafic schist in shear contact with carbonaceous pelitic schist.