Coming to a prospect like ADL with limited concrete information is a gamble, but then so is all exploration; it depends on the relevant company and their attitude to risk - obviously positive audited data mitigates against the level of risk and also gives a tentative indication of the minimum potential deposit size (many companies operate a 'cut-off' below which they will not operate depending on their business model).
Historically the area has been subject to artisanal mining for gold and copper in particular which indicates some level of mineralisation; but artisanal miners are able to operate at levels that mechanised mining cannot and to a time scale and work schedule all their own. Artisanal miners in Chile are extremely adept at mining the high-grade 'eyes' out of a manto or breccia or stockwork in often dangerous very confined spaces with a minimum of structural support and mechanised equipment; they are almost always halted by the water table or when their workings are become too structurally unsound. Mechanised miners need to work 24/7, produce bulk tonnages and ensure a consistent feed to the mill, so they need a known resource to base their mine planning on. Coming to something like ADL, which is a pure exploration play isn't something I would expect a mid-tier company to do, rather they would wait for a junior to explore first and firm up a resource before they committed time and money to the project.
The LDM may sound good on paper, but the sampling undertaken there is not fit for purpose and would not stand up to scrutiny. Sampling is a complex method of establishing ore tenor to a high level of confidence based on the structure of the deposit, mineralogy, chemistry and statistical behaviour of the metals involved and works by establishing a sphere of influence for each sample point. Sampling at LDM is very coarse (single samples covering several metres) and carries no geological context or explanation. Carbonate and oxide copper species can carry 60-90% copper. Hit a 20cm pod of cuprite in a 5m sample and you may get an assay grade of around 4% copper back; base your tonnage and grade calculations on this and you will get a very large figure, when in reality almost all the copper was in the little pod and the other 4.8m carries next to nothing. Your tonnage is more like poundage in this case. Refer back to some of my earlier posts regarding gold; correct sampling there is even more critical.
With regard to Perez; he was able to identify two porphyry bodies with some attendant alteration and may have felt able (issues with translation?)to infer a connection with the known inca and artisan-worked mineralisation on the plateau; that isn't something that could be done today without firm evidence. Simply having a porphyry, even one with evidence of hydrothermal activity does not mean you have an ore deposit on your hands. The Sillitoe model is just that - a model which illustrates an ideal situation; reality is often far more complex. In any event there are, as yet, no boreholes into these porphyries to quantify any mineralisation if it is present.
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