I thought I'd start a thread for people interested in discussing ore genesis models for the Veovaca deposit, Rupice,
Jurasevac-Brestic prospects and the broader Vares mineral field.
Understanding the ore genesis and deposit types can help with understanding the prospectivity and potentials for deposit size.
I thought I'd start by just providing some information from the ADT March prospectus, a copy of which you can find at the link below.
http://www.adriaticmetals.com/wp-content/uploads/2018/03/20180308_Adriatic-Prospectus_screen.pdf
The independent geological report completed by CSA global forming part of the prospectus says that
"polymetallic mineralisaton in the Vares District is associated with Middle Triassic rifting.
Mineralisation is predominately hosted in the matrix of a polymictic breccia of banded shale, siltstone or
sandstone clasts, both overlain and underlain by a succession of sandstone, siltstone, shale or limestone.
Mineralisation has also been observed by Adriatic geologists as semi-conformable with the lithology,
though limited in extent, Figure 10 shows the location of the Veovaca and Rupice Concession.
The Vares District hosts several varieties of zinc-lead polymetallic mineralisation:
• Irregular breccia hosted with moderate grade zinc, lead, barite, and silver (Veovacha and Orti)
• Massive barite with high grade zinc-lead-copper sulphides containing silver and gold (Rupice)
• Massive zinc-lead-copper-silver sulphide mineralisation in faults (Jurasevac, Brestic and Mekusa)
• Siderite breccia with medium grade zinc-lead sulphides with silver (Droshkovac and Smreka)
• Barite concentrations with zinc-lead sulphides (Brezik, Smailova Suma).
Mineralogy across the various mineral occurrences includes: sphalerite, galena, chalcopyrite, barite,
minor tetrahedrite, and pyrite; with associated silver and gold. There are also rare occurrences of stibnite
and cinnabar."
On page 13 of the CSA Global report it is noted that
"The mineralisation style at Veovaca and Rupice is considered by the Geological Institute in Bosnia to be of
sedimentary exhalative (SedEx) origin. However, there is limited information to confirm the presence of
finely laminated or bedded sulphide ore that characterise this deposit type........ Furthermore, the
presence of chalcopyrite and gold mineralisation particularly at Rupice and extensive breccia-hosted
mineralisation precludes the SedEx model......A possible model for the Vares mineral field is a hybrid SedEx-volcanogenic massive sulphide (VMS) deposit style known as Besshi-style VMS, whereby hydrothermal fluids of volcanic affinity deposit associated metals into the sedimentary environment in a similar way to SedEx mineralisation but driven by volcanic processes rather than sedimentary processes and on a smaller scale. In the Besshi model, there are many common features including syn-deposition of mineralisation and presence of barite;
however, the mineralogy and breccia textures are substantially different to those in a SedEx model
(Andrews, 2014).
The Besshi model accounts for the presence of chalcopyrite, barite and gold which are not normally
associated with SedEx deposits. It would also explain the relatively modest footprint of mineralisation
compared to the large scale SedEx deposits.
Subsequent brecciation and remobilisation of mineralisation during deformation of the sedimentary
package may have remobilised mineralisation into faults and fractures. Besshi deposits form in clusters
along stratigraphic horizons and can be restricted in aerial extent. A typical Besshi model is shown in
Figure 14 below. This would be appropriate given the geometry of the Dumitor Nappe and associated
geology shown in Figure 7."
The author of Figure 14 above, Franco Pirajno, is an Italian volcanologist and personal friend of mine who coincidentally is also the lead authored of this paper on Besshi deposits of the Bryah basin from which Fig14 has been taken. You can download the PDF of this paper at researchgate here
https://www.researchgate.net/public...for_tectonic_setting_and_geodynamic_evolution
Given that Franco in this paper classifies SFR's Degrussa deposit as Besshi style
" The VMS mineral systems occur near the north-east trending Jenkin Fault and comprise the giant and world-class DeGrussa and the Red Bore deposits. The nature of these deposits and their intimate association with terrigenous clastic rocks and dominantly marine mafic volcanic and subvolcanic rocks, as well as the common development of peperitic margins, are considered indicative of a Besshi-type environment, similar to that of present-day Gulf of California
its not hard to understand SFR's early motivation and involvement, taking up 7.7% of the ADT's issued capital in the IPO.
Just a note of clarification however for non-geologists out there. The DeGrussa geological setting although similar in some ways is 2,012 million years old (plus or minus 48 Ma) and the geology of the Veovaca deposit, Rupice and
Jurasevac-Brestic prospects date from the Lower Triassic, Middle Triassic and undifferentiated Jurassic-Cretaceous periods or from about 251.9 million years ago to 145.5 million years. This was the age when dinosaurs roamed the earth and the first true mammals came into being (lets hope ADT don't find too many rare fossils on the prospects). When DeGrussa was formed there were only microbial forms of multicellular life on earth (Eukaryotes). Surprisingly enough Eukaryotes were capable of both asexual and sexual reproduction. Just goes to prove you are never to young to start. Esh
(20min delay)
