Structures formed during ductile
deformation have been reactivated during the later brittle mineralisation
process. Two generations of folding are classified as: early recumbent
megascopic FI folds and FI shears which transpose the hinge regions, and later
upright F2 folds. S1 is folded about F2 folds which contain axial planar S2
crenulation cleavage. Vergence relationships between S1 and bedding indicate
that many of the mineralised structures occupy sites of FI folds which have
acted as plumbing systems for later gold mineralisation (eg Blackwater mine).
The Globe-Progress gold mineralisation is localised by a major jog formed by
sinistral strike-slip movement on two FI fault segments and mineralisation also
occurs in smaller jogs along strike (eg Sir Francis Drake, Happy
Valley-Merrijigs, Cumberland).

The
lodes of ribbon quartz which exploit the FI shears and local bedding planes, are
inferred to have mostly formed after the peak of metamorphism, possibly related
to the emplacement of Carboniferous granites. This was followed by a sequence of
vein deposition and wallrock alteration which consists of quartz-As/Fe sulphides

carbonate
- stibnite trace base metal sulphides and Bi-sulphosalts illitic
clay/sericite-chlorite. Gold at Globe-Progress is mainly encapsulated in
arsenopyrite. At Blackwater, free high fineness gold occurs in partings in lode
quartz with late sericite-chlorite. The above sequence of events is comparable
to that encountered in many intrusion-related gold systems throughout the
Southwest Pacific region. There is a spatial relationship between gold
mineralisation and dykes variably described as diabase, dolerite or lamprophyre.
Alkaline rocks occur in many Pacific rim and older goldfields and may possibly
be related to a magmatic source for gold
mineralisation.