http://en.wikipedia.org/wiki/Diorite
From the above linked information you can read that diorite can be porphyritc and, with the addition of some quartz, grade into monzodiorite and further into granodiorite. EVG reported:
“The gold values encountered deep in hole RSC-027 represent a significant exploration discovery in this year’s program at Rattlesnake Hills,” states Quinton Hennigh, President and Chief Geologist. “This hole intersected numerous intervals of intrusive porphyry with associated stockwork veining unlike anything we had seen previously. This suggests the possibility that a focus of mineralization may lie to the southeast, completely outside of the diatreme itself and further exploration may show that stockwork system is the connecting link between North Stock and Antelope Basin.”
From "numerous intervals" come the idea the hole may have intersected a "dike swarm" though faulted sections of one intrusive could produce the same result. But let us assume it is a dike swarm :http://en.wikipedia.org/wiki/Dike_swarm. These groupings of intrusive rock can be of varying sizes. What is interesting is they are porphyritic, indicating a multiple cooling history and that the rock moved upward after partial crystalization. This leads me to pose, along with the fact they are associated with stockwork mineralization, that the parent pluton below is the source of heat to drive the system and may have also contributed to the mineralization. It also gives rise to thoughts of a much larger system and to changes in mineralization as EVG drills deeper. Diorites and ther parent stock/plutons are often assocaited with copper porphryies, which can be sub-typed as copper/au porphyries and copper/moly porphyries.
EVG's initial discovery was pretty unmistakable as a Cripple Creek-type system. What they may have subsequently found could turn out to be an entirely new system in addition.
All this is just my musing with little evidence and none direct and be as far off as pluto.
"...unlike anything we have seen previously." Dr. Quinton Hennigh
Like Arte Johnson, I find this "very interesting." Please forgive my indulgence.
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