Open Collections

Mineralogy, paragenesis, and mineralogic zonation of the Silver Queen vein system, Owen Lake, central British Columbia

University of British Columbia

The Silver Queen mine, southeast of Houston, B.C., consists of a series of epithermal base- and precious-metal bearing veins hosted by Late Cretaceous volcanic rocks of the Tip Top Hill formation. Mineralogically, the veins are complex, displaying several discrete mineralizing stages characterized by the presence of certain sulfide and gangue species. The complexity of the vein mineralogy has presented a problem in assessing the systemic evolution of the hydrothermal system. This study describes in detail the nature of the mineralogy, dividing the assemblages present into four distinct paragenetic stages. Particular attention was paid to the occurrence of potentially economic phases (e.g. electrum). Sulfide phases which were compositionally sensitive to trace element variations were examined by electron microprobe to determine variations on single grain and deposit scales. Microbeam analysis also assisted in the identification of several sulfosalt species. Evaluation of the mineralogy and paragenesis allowed for the assessment of the evolution of the deposit. Paragenetically, the mineralization is divided into four distinct stages. The first stage is characterized by fine grained pyrite and quartz mineralization, with hematite abundant in the assemblage in the central segment of the most extensive (Number Three) vein. Barite, svanbergite, and hinsdalite become abundant towards the south end of the Number Three vein, with marcasite more abundant towards the north. Stage II is dominated by the presence of massive sphalerite and layered carbonate (calcite in the south, manganoan carbonates in the north). Stage III, however, is more complex. Mineralization consists of chalcopyrite, galena, fahlores (tetrahedrite-tennantite), electrum, quartz, and sulfosalts. Included in the sulfosalt assemblage are the unusual Pb-Bi-Cu-Ag species berryite, matildite, gustavite, and aikinite. The final stage of mineralization is volumetrically minor and is dominated by fine-grained quartz, pyrobitumen, and calcite. Minor element trends in tetrahedrites and sphalerites reveal a mineralizing fluid with a high degree of compositional variability. Tetrahedrite grains show well developed oscillatory compositional zoning in Sb, As, Bi, Ag, and Cu, while sphalerites are commonly visually well layered. The latter was found to be the main repository for the unusual metals Ga, Ge, and In, which are found in anomalous levels in Silver Queen ore. The Silver Queen veins are proposed to have evolved from fluids originating at depth to the south of the Number Three vein. Pulses of metal-bearing fluids interacted with cooler groundwaters, producing the observed distribution of assemblages. The presence of Ga, Ge, and In may have been sourced in an organic-rich layer exposed in several locales in the Silver Queen mine area.

Text

2010-11-08

For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.

http://hdl.handle.net/2429/29878

Geological Sciences

University of British Columbia

Graduate