Archean Au-Ag-(W) quartz vein/disseminated ... - Geology Ontario

8. Time Sequence of Deformation, Hydrothermal Alteration, Mineralisation and
Igneous Intrusive Events
A relative time sequence of deformation in the Break zone which contains the Kerr Addison
- Chesterville system, veining, alteration, mineralisation and mafic "albitite" dyke intrusion
has been built up using mapped cross-cutting relationships in ~55 areas of the mine. The
areas mapped between 1987 and 1990 are representative of 14 of the 20 Kerr Addison ore
bodies and 24 of the 28 levels developed in ore, and range from depths of 90 m to 1250 m
below surface. The results are summarised in Figure 32. The most important points shown
by this diagram are as follows:
(i) processes started with early, polygonal carbonate veining which appears to have
overlapped the beginning of ductile deformation in timing,
(ii) the interval of ductile deformation represented by the Break contains the period of Au-
quartz vein mineralisation (e.g. main stage Au-quartz veining in green carbonate ore related
to prominent "siliceous break" veins; main stage Au veins in flow ore),
(iii) physical correlation, through mapping in three different localities, has been made
between Au mineralisation in the green carbonate ore.and that in the flow ore,
(iv) mafic "albitite" dyke intrusion (3 generations, Aj to A3 ; or a continuum) is co-temporal
(see Section 9 below) with the main interval of Au mineralisation and was therefore also
contained within the interval of ductile Break deformation,
(v) the fact that there is significant intra-dyke intrusion Au mineralisation is definite, based
on observed cross-cutting relationships (see below); there is also no significant change in
dyke geochemistry (see Section 9), and
(vi) green carbonate ore shows ten distinct stages (five of which are Au-related) of quartz-
carbonate veining and associated alteration; these can be grouped approximately as follows:
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