With all due respect Cos, we are relatively confident of our understanding of the original model of how the Ni/Cu mineralization formed, gravity being a major factor.....and the resulting configuration of massive, overlain by matrix overlain by disseminated. Subsequent deformation and/or structural movement has obviously had an effect. Within any Ni/Cu "orebody" there is no apparent reason for the grade to increase with "drilling" depth unless the DDHs are oriented perpendicular to the dip, drilling from hangingwall to footwall.
With respect to multiple orebodies within a "nest", to the best of my knowledge, there are no hard or fast rules that predict higher or lower grades with drilling depth.
Respectfully submitted
geoprof
PS Very impressed with Wes Hanson's presentation.......lets give him and his staff lots of room and support!!!