Abstract
The copper orebody at the Victoria mine occurs in a breccia pipe emplaced in Permian limestone and calcareous sandstone. The mineralized part of the breccia appears to be due to collapse. Elsewhere, the breccia consists of mixed lithologies in a rock-flour matrix, and in some places, clasts are rounded and show rare graded bedding; these factors imply emplacement by upward-streaming. Monzonite porphyry dikes intruded the pipe during brecciation. Zonation and paragenesis in the district and downward within the pipe proceed from limestone to talc- and tremolite-bearing assemblages to diopside to garnet (averaging 77% andradite). Brecciation took place repeatedly during silication: tremolite clasts were cemented by diopside, diopside hornfels clasts were cemented by coarser diopside, and then by diopside and calcite, at which point brecciation ceased. Finally, garnet, calcite, quartz, and sulfide ore cemented the breccia. Copper is concentrated in an arcuate zone at one end of the breccia pipe. Late alteration of diopside produced saponite, talc, and local serpentine, whereas garnet altered to mixtures of hematite, calcite, quartz, and chlorite. The sequence is divided into (1) early contact metamorphism, (2) main-stage iron metasomatism and copper deposition, and (3) late-stage alteration, nearly isochemical except for the addition of CO 2 and H 2 O.
Published Version
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