Many large to giant ore deposits are hosted by breccia, in diatremes or related intrusive-to-volcanic complexes. These include IOCG deposits (Olympic Dam-type), diatremes, breccia pipes and carapace breccia in porphyry systems, and the interface between intrusive and fragmental parts of VHMS systems.

Volcanic Solutions has hands-on experience unravelling the emplacement and internal complexity of intrusion- and breccia-hosted ores.

For example, massive, unsorted polymict volcaniclastic rock juxtaposed with localised fountain-fed lava and strombolian spatter deposits are deposited by jets and fountains of debris and by mass movement. At deep levels fragmentation probably take place at the tops of stable dikes bounded by more-or-less solid walls whereas fragmentation in the middle and upper parts of the volcanic edifice take place within unstable, short-lived magma conduits built in weak, elastic wall-rocks.

Breccia-forming processes massively increase the reactive rock surface available for alteration and channel ore-forming fluids and magma. Distinguishing between tectonic and volcanic breccia, and understanding why breccia formed where, is key to unlocking the value in your exploration project. Contact us to find out how we can add value to your geology program.

McClintock, M., Marsh, J.S., White, J.D.L. (2007) Compositionally diverse magmas erupted close together in space and time within a Karoo flood basalt crater complex. Bulletin of Volcanology. doi: 10.1007/s00445-007-0178-6
McClintock, M., White, J.D.L., Skilling, I.P., Houghton, B.F. (2007) Physical volcanology of a large crater-complex formed during explosive eruptions of Karoo flood basalt, Sterkspruit, South Africa. Journal of Volcanology and Geothermal Research. doi:10.1016/j.jvolgeores.2005.11.012