IMPORTANCE OF METAMORPHIC PROCESSES AT THE NEPEAN NICKEL DEPOSIT, WESTERN AUSTRALIA.

This study at Nepean demonstrates the complexity of changes that may occur in Fe-Ni sulphide ores during metamorphism, and indicates the necessity for caution in the interpretation of ore sections in terms of magmatic processes alone. In this case, the enclosing rocks appear to have been initially partly serpentinized, then dehydrated at high temperature and pressure, and subsequently reserpentinized. The complex interpaly of all processes and the transient nature of sulphide compositions and textures make a unique interpretation of the present configuration, mineralogy and geochemistry of the ore virtually impossible. The various effects of the processes of the sulphide ores must be considered, however, before an attempt can be made to reconstruct the pre-metamorphic nature of the mineralization.