Page 308 - Handbook of Gold Exploration and Evaluation

Structures
Fundamental faults or `breaks' Magma and fluid conduits connecting lower crustal site of ore-fluid
generation with upper crustal site of ore deposition; sites of
seismogenic `fault-valve' behaviour necessary for the development
of supra-lithostatic fluid pressure to drive fluids into local gold-rich
source rocks and allow cyclic fluid-pressure-release mechanism
for gold deposition
Local faults and folds Dilational environment allowing fluid degeneration by
decompression or `throttling' and (or) CO 2 effervescence, leading
to mineralisation and alteration

Mineralisation and alterations
Carbonatisation along fault zones Indicates that deeply derived, CO 2 -rich gold-mobilising fluids have
been circulating through fault zone
Silicification, pyritisation, K- or Na-metasomatism, quartz- Gold-mobilising fluids have interacted with a gold source rock with
carbonate-sulphide veins the mineralogy of a felsic igneous rock (a felsic igneous rock or a
clastic sediment)
Syn-volcanic peraluminous alteration, VMS or Ni-Cu Local gold-rich source rocks (?)
mineralisation, pre-tectonic porphyry-type Cu-Au mineralisation