Petrology and Cu-Ni-PGE Mineralization of the Bovine Igneous ...

scanning electron microscope equipped with an energy dispersive spectrometer system (EDS).
The EDS was used to acquire standardless analyses, which yielded semi-quantitative (~.5%
error) major element compositions of the olivine and augite. Thirty one out of the 79 total
polished thin sections collected from drill core 08BIC044 were selected for analysis.
The samples chosen for mineral chemical analysis occur at regular intervals within each
stratigraphic unit. Within each unit, samples were taken that best represented the unit and that
contained the least altered olivine grains. The selected polished thin sections were coated with
approximately 20 nanometers of carbon using a Denton vacuum carbon coater. Applying a
conductive carbon coat to the sample surface allows for the dissipation of electrons, which will
otherwise build up on the surface and result in sample charging and beam deflection.
The analyses were carried out in seven 3-4 hour sessions, which allowed for analysis of
multiple olivine and augite grains in three to five samples. An accelerating voltage of 15kv
was used for the electron beam throughout each session. During each session, the EDS
spectrum was calibrated to a thin piece of copper tape attached to the sample holder. After
calibration, five to eight analyses were acquired of olivine and augite grains from three
different areas on each thin section. Five were acquired in each of the three areas if only augite
was present, whereas eight analyses were acquired if olivine was also present. Each analysis
was carried out for a 20 second count time. The system was recalibrated on the copper tape
between the analyses of each sample.
2.5 Lithogeochemical Analysis
Twenty seven samples from drill cores BIC01-01, 08BIC044, and one field sample
from the marginal zone, were chosen for lithogeochemical analyses. One or more samples
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