Highly altered felsic metavolcanics associated with the Kidd Creek, Ontario, Cu-Zn massive sulfide deposit show a large range of Sm/Nd ratios and yield a Sm-Nd isochron of 2674 ± 40 Ma (initial ratio ϵNd = 1.55 ± 0.30), which represents the time of rare-earth-element redistribution during intense hydrothennal alteration. That the Sm-Nd age is consistent with age constraints on ore deposition provided by precise U-Pb zircon data indicates contemporaneity of ore deposition, hydrothennal alteration, and rare-earth mobility. The age is therefore interpreted as a minimum age of ore deposition. In contrast, the Rb-Sr age of the altered rocks, as well as the metavolcanic rocks outside the alteration zone, has been reset at 2576 ±26 Ma, most likely as a result of widespread low-temperature metasomatism unrelated to ore deposition. Our results suggest that Sm-Nd dating could be a useful tool in the study of ore deposits and, potentially, in the study of a wide range of mineralizations.

Initial ϵNd(T) values for massive ore, altered felsic volcanics, and their weakly altered precursors are identical, indicating derivation and redistribution of light rare-earth elements within the altered footwall volcanics. These data suggest that the footwall volcanics have also supplied part of the base metals to the stratiform ore.

First Page Preview

First page PDF preview
You do not currently have access to this article.