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

lower feldspathic wehrlite unit in 08BIC044 is distinctly variable in modal mineralogy and
texture and alteration in the 30 meters above the basal contact (Fig. 25A). However, rather
than being heterogeneous, the basal zone in 08BIC044 shows systematic changes in mode and
texture up from the basal contact. In the basal zone, the following changes are observed up
section:
• Olivine mode increases while plagioclase and augite decrease (Fig. 19);
• Grain size (defined by olivine) grades from medium fine to medium coarse (Fig. 20);
• Plagioclase habit changes from subpoikilitic to poikilitic, with oikocrysts reaching a
maximum diameter of 12 millimeters (Fig. 20);
• Augite habit changes from subprismatic granular to poikilitic with oikocrysts reaching
7 millimeters across (Fig. 20); and
• Alteration of olivine to serpentine grades from strong to moderate while plagioclase
alteration increases from moderate to complete (Fig. 20).
The upper three quarters of the lower feldspathic wehrlite unit shows a reversal of
many trend observed in the basal contact zone. These include a gradual increase in modal
augite and amphibole from 20 to 35% and 5 to 20% (Fig. 28A) respectively, and a decrease in
olivine mode from 60% to 40% (Fig. 19). Biotite is present in the unit in modal percentages
from trace to 4%. Mineral textures in the upper 90 meters of the lower feldspathic wehrlite are
generally constant and consist of anhedral granular biotite, poikilitic plagioclase, poikilitic to
subpoikilitic augite and amphibole, and subhedral granular olivine (Fig. 20). Alteration is also
uniform in the upper part of the lower wehrlite unit with weakly altered augite, strongly to
completely altered plagioclase, and moderately altered olivine (Fig. 25B).
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