| Mineralizing and non-mineralizing fluids involved in the N81 deposit at Pine Point were characterized using microthermometric, bulk geochemical and strontium isotopic analyses. The mineralizing fluids are highly calcic brines (23 wt% CaCl2-NaCl), which formed at a minimum temperature of 82°C. Geochemical data suggests that at least two fluids were responsible for the mineralization, which varied in salinity and strontium composition, (78Sr/86Sr=0.7073 to 0.7152; average=0.7116) but were relatively isothermal and likely derived from a mixture of highly evaporated seawater and an 87Sr-rich fluid. The post-ore fluids were highly radiogenic (87Sr/86Sravg=0.7149) NaCl-CaCl2 brines (0 to 15 wt% equivalent NaCl-CaCl2; average=9 wt% equivalent) and geochemical data suggest the fluids may have been a mixture of a saline brine and meteoric water. In general, Sr isotope ratios suggest that the fluids became more radiogenic with the progression of the paragenetic sequence and that the 87Sr is likely sourced from clastics and/or basement rocks. |
