The
Martha deposit in Waihi, New
Zealand, is a giant adularia-sericite
epithermal gold-silver deposit that formed 6.0 to 6.1 Ma, and has produced over
6.4 Moz gold and 39.9 Moz. Fluid inclusion analyses were undertaken on a limited
number of vein samples from Martha. The results from this eight week student
project are preliminary but agree with previous studies. There is little
variation between primary and secondary inclusions and between different vein
types, except that homogenisation temperatures of the inclusions in sphalerite
grains are on average 20 to 30C higher than the average quartz vein values.
Overall the temperatures of homogenisation ranged from 182 to 258C and final
ice melting temperatures ranged from 0.0 to 2.8C. Unusual black inclusions
were also found associated only with the ginguro bands. Some of these appear to
be solid sulphide inclusions but others are not so clear.