Oxygen isotope geochemistry of the Sullivan massive sulfide deposit, Kimberley, British Columbia

Hydrothermal evolution of the deposit. Potential applications of isotopic analyses to exploration for stratabound, stratiform, Pb-Zn-Ag deposits. The deposit is hosted by the Proterozoic Aldridge Formation. The delta (super 18) O results for samples from the Aldridge range from 10.0 to 13.1 per mil with an average of 11.4 + or - 1.0 per mil. Oxygen isotope results from the tourmaline alteration zone, located in the footwall of the western, proximal ores, range from 10.7 to 13.1 per mil with an average of 11.9 + or - 0.8 per mil. The similarity between values for the tourmalinite and the Aldridge Formation suggests that the fluids which produced the tourmalinite alteration did not significantly alter the primary (super 18) O/ (sub 16) O of the host sedimentary units. Isotopic values for samples from the albite-chlorite alteration zone, located in the hanging wall of the proximal ores, range from 6.1 to 7.7 per mil. Such values indicate that there is a distinct difference in the isotopic composition of the albite-chlorite zone relative to unaltered country rocks. The following sequence is proposed: the first hydrothermal stage consisted of the migration of low-temperature (<100 degrees C), boron-rich fluids up permeable zones, causing the development of the tourmalinite alteration zone. Subsequent to this event, hotter (approximately 150 degrees C) Pb-Zn-Fe-bearing fluids rose through the same zone at Sullivan and deposited sulfides on the sea floor. The final hydrothermal event was the alteration of the tourmalinite, ore, and hanging-wall sedimentary units to produce the albite-chlorite alteration assemblage. The fluids which produced the albite-chlorite assemblage were most likely more saline than normal seawater and had a temperature of 250 degrees C or more.--Modified journal abstract.