Page 116 - Handbook of Gold Exploration and Evaluation

96 Handbook of gold exploration and evaluation

2.16 Uneven distribution in geological time of three important types of mineral
deposit (derived from Meyer (1981), Lambert and Donnelly (1992) and Barley
and Groves (1992)).

which the transport of metal is strongly dependent upon oxidation-reduction
(e.g. Holland, 1984)
· secular decreases in global heat flow as responsible for the restriction of
Kambalda-type, komatite-associated Ni deposits to the Archaean and Early
Proterozoic; Archaean greenstone is typically associated with Precambrian
gold deposition; continental silicic volcano arc successions host precious and
other epithermal metal deposits; and porphyry copper-gold deposits occur
with deeper-level intrusives.
The abundance of gold and volcanic-hosted massive sulphide and Kambalda-
type komatite-associated Ni mineralisation in late Archaean greenstone belts and
sedimentary basins may have been due to rapid growth and stabilisation of
continental crust with high global heat flow. Important peaks in the abundance