Here is another explanation of what we are talking about...

Here is another explanation of what we are talking about courtesy of my Geologist Dr Google.

Breccia pipe formation is related to evolution of an underlying magma chamber. In a favored model, magmatic fluids exsolve from the magma and rise and collect as one or more large bubbles at the roof of the chamber. As more fluid accumulates and the fluid bubble increases in size, the roof of the chamber eventually can no longer support the weight of the overlying rocks. Collapse of the overlying rocks begins, and the breccia pipe propagates upward toward the surface. This porous column of collapsed rock is a conduit of open spaces and fractures, through which aqueous magmatic fluids can easily travel accounting for high concentrations of copper mineralization. The aqueous magmatic fluids are thought to be the same composition as those that produce porphyry copper deposits, leading to the conclusion that such a system might be present at depth beneath the breccia pipes.