Timing of Gold Introduction in the Late Archean Tectonic Framework of the Canadian Shield: Evidence from U-Pb Zircon Geochronology of the Abitibi Subprovince
Soussan Marmont, F. Corfu, 1989. "Timing of Gold Introduction in the Late Archean Tectonic Framework of the Canadian Shield: Evidence from U-Pb Zircon Geochronology of the Abitibi Subprovince", The Geology of Gold Deposits: The Perspective in 1988, Reid R. Keays, W. R. H. Ramsay, David I. Groves
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The maximum age of gold mineralization and the chronostratigraphy of the Timmins and Kirkland Lake-Matheson areas in the external zone and the Detour Lake mine in the internal zone of the Abitibi subprovince, Ontario, are established through U-Pb zircon geochronology. In the Timmins area, two episodes of felsic volcanism are determined at 2,727 ± 1.5 and 2,698 ± 4 Ma which support existing stratigraphic interpretations. In the Kirkland Lake area, three periods of felsic volcanism are dated at 2,747 ± 2 (J. K. Mortensen, pers. commun., 1988), 2,705 ± 2, and 2,701+3−2 Ma. In the area south of the Kirkland Lake-Larder Lake break, the dates do not correspond to the current stratigraphic interpretation, rather, they indicate reversals which possibly resulted from stacking. In the Matheson area, north of the Destor-Porcupine break, an episode of felsic volcanism is determined at 2,714 ± 2 Ma. The dates in this area indicate structural repetition of some units. Therefore, caution is exercised in stratigraphic correlation across structural discontinuities.
The youngest lithologies hosting gold mineralization consist of late Archean intrabelt intrusions which cut the youngest, folded and/or tilted volcanic rocks. They are silica-saturated quartz porphyries which in the Timmins mines are 2,691 to 2,688 Ma and silica-poor or undersaturated monzonites and lamprophyres(?) which are 2,678 to 2,673 Ma.
In the Detour Lake mine, feldspar porphyry which is the youngest lithology hosting gold-bearing structures dates at 2,722+3−2 Ma. An apparent age difference between the late plutonic event of the internal and the external zones of the Abitibi subprovince suggests a different timing of cratonization of the two terranes.
Gold mineralization shows a distinct spatial and temporal association with major deformation zones such as the Destor-Porcupine and the Kirkland Lake-Larder Lake breaks, and the silica-poor or undersaturated intrusions, emplaced along these breaks. Gold is temporally separated from volcanism by 25 Ma and from emplacement of quartz porphyries by 13 to 15 Ma. Along the Destor-Porcupine break, gold is synchronous with or later than 2,673+6−2 Ma.