RE: GEOCHRONOLOGY OF THE RUDALL PROVINCE5 Jul 2020 01:52
Ok little follow up. It's a long publication by the GSWA but i've skim read a few bits. So the authors are tentatively suggesting that there is potential for porphyry Cu-Au mineralization within the Rudall in the Krackatinny Supersuite. This hypothesis relies on the timing of a specific orogenic event called the Yapungku orogeny which joined N and W Australian cratons together. The authors interpret this event to be much younger than traditionally thought of at around 1.76 billion years ago. If this event happened later than 1.76Ga, then there is more of a chance of porphyry style mineralization as that particular piece of land remained on a plate margin for a longer period of time. Before any continental collision happens, we have a subduction zone and later we get full continental collision according to plate tectonic theory.
Without getting really technical and because I haven't read the full document (104 pages!), there is evidence that supports the Krackatinny supersuite being emplaced in an arc setting and that these magma's were hydrous. A key observation is that some of the granites are Sr/Y enriched which is a geochemical parameter that is observed in other porphyry intrusions worldwide. So if present in the Rudall licence, these rocks might be mineralized.
I have had some ideas regarding if the basement is pre-enriched in metals. This suggests that might be the case. The granites within the Paterson Orogen surrounding Telfer etc must have been sourced from somewhere i.e something must have melted. If the granites are sourced from melting the Rudall complex and if the Rudall complex was pre-mineralized, we will remobilize those metals within the Rudall basement. If one of the sources of metals is indeed the Rudall complex, more deposits will be likely because the Rudall underlies the orogen. So any localized remobilization and then concentration of those metals may produce an ore deposit.
It's going to be interesting to see what results come out of the Rudall licence in terms of grade, metal tenor and rock types.
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