Three Possible ScenariosThe term orogenic gold deposit was defined by Groves et al. (1998) as a coherent group to replace a wide variety of terms that referred to gold-only deposits.
Orogenic gold deposits are commonly vertically-extensive, gold-only deposits that formed in broad thermal equilibrium with their wall-rocks from low-salinity H2O-CO2 ore fluids at crustal depths from 2 to 15, and arguably up to 20 kilometres, as summarized by Goldfarb and Groves (2015).
note: since, Groves has modified his definition to include Cu, Ag, Mo, as well
(Source: David I. Groves (2019) Orogenic gold deposits: part of a global dynamic conjunction between subduction and gold, ASEG Extended Abstracts, 2019:1, 1-3)
D.R. Cooke, ... R.M. Tosdal, in
Treatise on Geochemistry (Second Edition), 2014
13.14.1 Introduction
Porphyry ore deposits are the Earth's major resources of copper, molybdenum, and rhenium (Sillitoe, 2010) and also provide significant amounts of gold, silver, and other metals. Mineralization styles include stockwork veins, hydrothermal breccias, and wall-rock replacements.
Porphyry deposits form at depths of approximately 1–6 km below the paleosurface due to magmatic–hydrothermal phenomena associated with the emplacement of intermediate to felsic intrusive complexes (Seedorff et al., 2005).
Most porphyry deposits have a spatial, temporal, and genetic association with geodynamic processes at convergent plate margins where hydrous melts are generated in the subarc mantle. These oxidized melts transport metals and volatiles to magma chambers located in the mid to upper crust, where fractional crystallization and volatile exsolution result in porphyry ore formation.
Porphyry deposits are typically classified on the basis of their economic metal endowment (Kesler, 1973). Subtypes include porphyry Cu, Au, Mo, Cu–Mo, Cu–Au, and Cu–Au–Mo. There are also examples of porphyry Sn and porphyry W deposits (Seedorff et al., 2005).
GeoDynamics - the general term for models of the large-scale behavior of the Earth. Some key (but generalized) aspects of geodynamic models are: - gravity couples to density contrasts to give rise to stress; - rock rheology (relationship between imposed stress and consequent deformation of solid rock); and - temperature as a function of heat generation, conduction, and movement of material (advection). One point not mentioned at this point is change -ability in relation to magnetic resistivity
High Chargeability elements include Cu, Au, Ag
High resistivity indicates pyrite.
Current data from Casino at depths indicates high chargeability and low resistivity which means Cu, Au, Ag type minerals Theoretically, all data at this point demonstrates a very high grade deposit that gets richer in minerals the deeper we go. IMHO, it is 99% certain we are a hit. But Rio probably does not want to take a chance that we fall into the 1% dud category. The data from this drill for once and all prove that we are not a dud.
A few months ago, Paul spoke with the Rio geologist Chris and said “you know, the best deal Rio is going to get is pay the cash now or else they will pay a lot more in the future”. Chris responded by saying “yes, I know, but these majors move very slowly”. Possible scenarios moving forward: - The drill results are a hit on spec (Rio geologists are overseeing the campaign so they will know) and negotiate a deal quickly to avoid a bidding war - Wait until the drill results are officially in which is not really necessary - Wait another year for the FS at which time there will be a bidding war Rio’s choice. But at this moment, we hold the prize.