Long-term metallogenetic concentration and recycling processes, involving , magmatic/hydrothermal, sedimentary and metamorphic processes, prevalently starting off during the Percambrian with Mn-enriched BIFs. All world-class Mn deposits show such a poly-phase and poly-type enrichment
See , e.g.,
DILL, H.G., PÖLLMANN, H. and TECHMER, A. (2013) 500 Million years of rift- and unconformity-related Mn mineralization in the Middle East: A geodynamic and sequence stratigraphical approach to the recycling of Mn.- Ore Geology Review 53: 112-133.
HGD
Harald Dill, how does Groote Island, northern Australia fit that scenario?
Brian Stevens,I know the Proterozoic McArthur Basin very well especially with regard to their unconformity-related U deposits (Ranger & Co) which have seen sedimentary, metamorphic and magmatic-hydrothermal processes involved in the concentration process. In principle, the elements are also recorded from Groote Eylandt in the Gulf of Carpentaria, Northern Territory, in Arnhem Land. You have shallow marine primary pisolitic and oolitic Mn ore, secondary concretionary Mn ore, and supergene Mn ore. The ore deposit is located in flat lying Cretaceous rocks deposited unconformably on a Paleoproterozoic crystalline to Mesoproterozoic basement (is the time of the BIFs). The main Mn ore enriched in pyrolusite, cryptomelane and manganite is bound apart from lenses to WNW- striking joints intersecting the basement quartzite or directly rests on the basement quartzite.
You have a low-grade metamorphic basement, shallow sedimentary-marine deposits and hydrothermal fluids circulating in the structures cutting the unconformity. And last but not least the supergene black Mn ore which is also common to most Mn deposits elsewhere in the world.
I do not see a great difference to the general scenario on Mn accumulation recorded by me above ?
HGD
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