Metamorphism and deformation of Archean gold deposits: the importance of structural documentation in the evaluation of gold mineralization

Conference · Tue Jan 01 04:00:00 EST 1985 · Geol. Soc. Am., Abstr. Programs; (United States)

OSTI ID:6318110

MacGeehan, P J

Archean gold deposits are comparable in almost all respects to their Phanerozoic counterparts, but differ in the extent of superimposed metamorphism-deformation. In many instances this has obscured the original mode of emplacement of the gold mineralization, in that (1) the primary structural-stratigraphic setting of the mineralization is disguised by later deformation, and (2) the deposits are almost invariably metamorphosed, and blocking temperatures established on the basis of current equilibrium ore-mineral assemblages or even fluid inclusion filling-temperatures are either suspect, or represent the P-T of subsequent metamorphic events. The effects of this overprint are particularly important when evaluating mineralization emplaced pre-peak metamorphism, in consequence of which there has been little support for the presence of Archean epithermal (unconformity - related) mineralization, or of epigenetic and/or exhalative mineralization emplaced contemporaneous with volcanism. This problem is examined in some major currently-producing West Australian gold mining camps, including Norseman (3.8 M.Oz), Kambalda (1.3 M.Oz) and the Kalgoorlie Golden Mile (36 M.Oz). The solution lies in detailed structural documentation and a reconstruction of the original environment of deposition of the gold mineralization, viewed through the larger-scale perspective of greenstone-belt evolution.

• Research Organization: Western Mining Corporation Ltd., Kalgoorlie (West Australia)
• OSTI ID: 6318110
• Report Number(s): CONF-8510489-
• Conference Information: Journal Name: Geol. Soc. Am., Abstr. Programs; (United States) Journal Volume: 17
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580300* -- Mineralogy
Petrology
& Rock Mechanics-- (-1989)
AUSTRALASIA
AUSTRALIA
DEFORMATION
GEOLOGIC AGES
GEOLOGY
GOLD ORES
INCLUSIONS
METAMORPHISM
MINERALIZATION
MINERALOGY
ORES
PETROGENESIS
PETROLOGY
PRECAMBRIAN ERA