Structure, Stratigraphy, and Primary Setting of the Kidd Creek Volcanogenic Massive Sulfide Deposit

Abstract Although the Late Archean Kidd Creek volcanogenic massive sulfide deposit is one of the largest and highest grade deposits of its kind in the world, a detailed documentation of its geology has hitherto not been available. This paper presents the results of a detailed and integrated investigation of the mine structure and stratigraphy and places these in a regional context of the southwestern Abitibi greenstone belt. The Kidd Creek orebody consists of a series of stacked lenses hosted by a complex, proximal volcanic stratigraphy associated with a ca. 2717 to 2711 Ma, subaqueous, high silica rhyolite complex that developed diachronously within what appears to have been a linear graben or half-graben structure. The mine stratigraphy has experienced polyphase folding and faulting and presently outlines a northwest-trending reclined fold (F1) that is part of a larger interference structure involving one older and one younger regional folding event. The various ore lenses and their chalcopyrite stringer stockworks occur as variably stretched bodies on the western, steeply overturned limb of the reclined F1 fold, which is referred to as the “Kidd Creek mine fold.” Internal deformation of the orebodies is strong but heterogeneous. Ore lenses have been tightly folded, thickened, partly transposed, and strongly elongated parallel to a steeply plunging stretching lineation that is subparallel to the axes of the Kidd Creek mine fold and its parasitic structures. On the scale of the mine, the fold interference structure is coaxial and sufficiently systematic so that the orebody can be unfolded and a semiquantitative reconstruction of the primary geometry, stratigraphy, and setting can be obtained. The resulting model is both simple and comprehensive and allows most of the detailed aspects of this giant deposit to be placed in a spatial and temporal context. A detailed stratigraphic section and description of the rock units document the entire Kidd Creek stratigraphy and provide the framework in which detailed parallel studies on the U-Pb geochronology, chemostratigraphy, and ore genesis have been carried out. Long-lived venting into the volcaniclastic fill of a relatively stable graben or half-graben structure, bounded by at least one deeply penetrating synvolcanic fault, is seen as the key control that led to a single giant deposit.