IOCG & Radiometrics for Dummies

I just tried to wrap my head around IOCGs and radiometrics. Why? Rob Heaslop's final report and Inca's IOCG exploration model focuses on it (see Awarded NDIBK04&01 thread for summary).

Interested? Grab a cuppa...

Part 1: What are IOCGs and how do you find them... think basins or dams!
The key to the formation of IOCG’s that there has to be an abundance of oxidized groundwater in the country rock to mix with the magmatic water derived from the intrusion. The intrusion of hot water into water saturated rocks means that the water flashes to steam and this fractures the rocks and produces breccias. The high iron content and oxygenated environment means that the alteration is characterized by abundant red hematite and black magnetite both oxides of iron. (See below for Inca’s East Tennant cross section from recent presentation and @Goldbug23 Jumping Spider comparison to OD)





IOCG Iron Oxide Copper Gold Ore Deposits ore is often striking to look at and it is often very red from the hematite content, blue from bornite or yellow-green from various uranium oxides.

IOCG Exploration for IOCG’s can use a number of techniques, starting with the geophysical methods magnetics is a very valuable tool as IOCG systems are almost always have a magnetic signature and are caused by the abundant magnetite.




The gravity data of Olympic Dam shows a clear bull’s-eye coincidence with the deposit. The presence of massive sulfides also means that electromagnet or EM surveys can be used to detect deposits.

If a deposit of occurs at surface and is uranium rich as in the case of Olympic Dam (except that one is buried) then airborne or ground radiometrics will detect the radiation given off by the uranium and any associated potassic alteration... see Part 2 for a deep dive into radiometrics.

https://www.911metallurgist.com/blog/iocg-iron-oxide-copper-gold-ore-deposits