Paterson Province 2018 and future, page-2

This post is not so much a collation of data as one that provides the background for the geology of the Paterson Province in broad strokes.  It largely comes from musings about the possible genesis for Telfer mineralisation and what that implies for exploration of the area.

Geochemical evidence for Telfer is not conclusive with both magmatic and sediment sourcing of elements present:

Goellnicht et al. (1989) and Schindler et al. (2016) suggest the high content of major elements (Na, Mg, K, Ca, Fe, Mn, Cu, Zn, Pb, Co, Ni, Ag, Ce, La, Y and Mo),and high homogenisation temperatures in all fluid inclusion assemblages are compatible with involvement of a magmatic hydrothermal fluid. However, Rowins et al. (1997) present C, O, B, Pb and S isotope data from both ore sulphides and alteration minerals (carbonates and tourmaline) they interpret to indicate ore fluid solutes were derived from sedimentary rocks of the Yeneena Supergroup

GEOLOGY

Mostly leaving out the global scale and plate tectonics there are multiple scales to look at the Paterson Province.  While there is a lot of information below it is only the tip of many different icebergs of knowledge each of which can be expanded on and will change as more research is done.

Broad scale:

Courtesy of Greatland Gold:

Porter Geoscienceis a good and valuable source which provides excellent broad to local scale research for Nifty and Telfer among many deposits.

For this post Porter Geoscience (PGC) images (2 and 3 above) show more regional detail and begin to focus in on the Paterson province and Yeneena basin (Image 2) that contains the primary area of interest for AZY/Rio/NCM and many others.

Slightly paraphrased from PGC's Nifty summary is this description of the

Regional SettingNifty/Telfer/Winu etc are... situated within the NNW to NW trending, >1000 km long by 150 to 200 km wide Paterson Orogen which fringes the northeastern margin of the Archean to Paleoproterozoic West Australian Craton, and merges with the Musgrave Orogen to the SE. The Paterson Orogen is composed of two main elements, the Paleo- to early Mesoproterozoic metamorphosed igneous and sedimentary rocks of the Rudall Complex, and the unconformably overlying ~9 to 13 km thick, ~850 to 824 Ma Yeneena Supergroup of the >24 000 km² Neoproterozoic Yeneena Basin.

For non geologists, and even me, to understand this paragraph is not straight forward as it involves so many technical terms and references.

This attempt to "unpack" it is simplistic but let's see how it goes as it could provide a good context for what follows afterwards.

Since the Earth grew from being a collection of dust, maybe some 4500 My ago, there has been a continuing process of change to it.  Early areas that became solid have, in some instances (e.g. Pilbara craton c 3000+My) become the nucleus for later complex zones to accumulate as is shown by the way the Capricorn (~1800Ma) and Paterson (~800Ma) Orogens "stick" to its NE margin (image 1).  

Part of the orogenic process can be the development of mountains and adjacent basins that accumulate vast amounts of sediments from the erosion of the mountain building.  Some intrusives and lots of structure are added during formation and later so not simple environments.....

Such processes are occurring on a world wide basis and lead exploration geologists to check out similar environments in diverse localities.  The age of the Paterson Province is very similar to the Central African copper belt and this provides a model which can be applied in the search for new or serendipitously different mineral deposits.  

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These two images put the age dating into some context.  Geochronology (dating of units, rocks etc.) is very important - much like getting the time line correct to solve a crime - for exploration a major clue as to economic mineral formation.  Sometimes there are multiple "culprits"

Part of this linked post attempted to put some of the economic mineralisation in the NW of WA into a chronological context.

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Telfer (PGC) and Nifty (PG) - mined since 1975 (1971 "discovery") and 1993 (1981 new discovery) respectively and have provided much of the data needed for exploration models in the area.  

A brief comparison:

1. Telfer Cu/Au; Nifty Cu only.
2. Telfer - domes (anticlines), Nifty - basin (syncline).
3. Host lithologies are sediments in both cases though from different formations. 
4. The movement of fluids through sediments and subsequent deposition in chemical and/or structural traps appears to be a common feature at Telfer and Nifty.
5. Intrusives with obvious links to mineralisation appear to be absent at both deposits.  There is a hint that there is an intrusive related heat source that powered some of Telfer mineralisation though the role appears to be minor.
6. An actual age for both is still the subject of debate but somewhere between 600-800 My (e.g Nifty geochronology (2007)) is probable. Individual samples give more accurate dates but  what they mean is open to interpretation.
7. Deep weathering at both - 200m and locally on strong structures to 500m.  This can impact on mining economics and subsequent recoveries.
8. Exploration: Telfer: location of outcropping gossans on distinctive domal feature followed up ultimately by drilling; Nifty: geochemistry combined with Cu stained outcrop and float followed up ultimately by drilling.   Simplified versions which leave out why WMC and the forerunners of NCM were there in the first place.

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Telfer details

Photo pre mining:

The "reef" systems that underlie this and adjacent, domal features reflect the close relationship to stratigraphy that led to early theories of mineralisation forming at the same time as the beds.  Ten plus years of mining produced "subtle" conflicting evidence that overturned that theory into what is now accepted as selective replacement of receptive stratigraphic units and associated structures PLUS numerous cross cutting mineralised features.

The number of "reefs" is probably simplified.  At a depth of 1000m below surface the I30Q reef seems to have been a very significant discovery.

The volume of stockwork and discordant mineralisation is large (hundreds of millions of tons at lower grade - not dissimilar to Calibre??? - but economically challenging on its own without the higher grade reefs perhaps).

Sources Major 2014 NCM NI 43-101 report on Telfer; and PGC Telfer.

Nifty detail

Surface expression includes some gossan outcrops which partially reflect the Nifty syncline and would attract an exploration geo's attention especially if there were some secondary copper minerals (malachite/azurite etc).  Most outcrops like this turn out to be teasers but occasionally are all that is visible at surface.  Most gossans like this have been checked out already so searching under ever deepening cover is main option left.   Source: Structure, alteration, and mineralisation of the nifty copper deposit

Plan and schematic sections

Studies suggest the mineralisation came from fluids circulating in the sediments relatively soon (in geological terms) after they were buried around some 800Ma ago.  

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There are numerous variants of Telfer and Nifty in the Paterson Province.

The Maroochydore Cu deposit is similar to Nifty, but its location and lower grade (and ??) mean it is yet to be exploited even though it is larger.  

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O'Callaghan's is another large undeveloped deposit but is of somewhat different genesis.  Intrusive related skarn.

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Havieron appears to be hosted in sediments that post date Telfer (Which in turn postdates Nifty) so there is a probable wide time frame as well as spatial frame that leads to hopes of further significant discoveries in the broader Paterson Province.  Winu???

The movement of fluids through sediments is important for the genesis of many deposits.  Not limited to these by any means.

• Mt Isa/Broken Hill etc etc 1550-1700Ma
• Zambian/Central African copper c700+-Ma;  Telfer Nifty etc
• MVT's such as Admiral Bay and Cadjebut  - different ages ~450Ma and ~390Ma resp.

Toss in a few intrusives with possible porphyry or IOCG affinities and it is a geos party.  Weird but whatever rocks your boat and adds to the SP when things go bang.

The topic is too large to really do it full justice. 

The above is a shotgun draft of what AZY, Rio have considered in way more detail.  Then it gets down to the chance that the ground one holds contains a decent size deposit.  Hopefully NEAROLOGY doesn't always mean near but actually on AZY ground for one of the bigger ones.