GSR (ASX) Ann: Correction to previous announcement dated 1 Sept 2022

Originally posted by OldGeo: ↑

Hi aubin,
Great contribution and very informative. Would you be able could add the rock types for hole 1 (MTJV001) alongside your disseminated sulphide distribution column and repost for completeness; no worries if you do not have time .

On the heavily disseminated sulphides in the black shale or black shale/chert, my main question would be how to extract the metals economically/ efficiently. As we know, several GAL holes where heavily disseminated sulphides have been logged, also occur in the black shales/chert. Increased metal contents in most black shales relate to increasing organic carbon content, decreased sedimentation rate and the type of organic matter present where the metals are scavenged from the overlying column of seawater during sedimentation. The two most likely genetic models for shale-hosted Ni–Cu–PGE mineralisation are derivation from hydrothermal fluids associated with Volcanogenic Massive Sulphide (VMS) or Sedimentary Exhalative (SEDEX) systems, or synsedimentary formation.

However Mt Thirsty has ultramafics and intrusive sills. Some of the principal observations that relate to many, but not all, major Ni sulphide deposits include such features as available source of metals (mafic and ultramafic magmas), a source of S (sulphur) to saturate the magma (e.g., sulphidic black shales), gravitational segregation of dense immiscible sulphide liquid, and concentration of the sulphides into physical traps at the base of intrusions or within conduits (hydrothermal?). This is closer a Mt Thirsty-type origin.........link below.

http://www.dmec.ca/ex07-dvd/E07/pdfs/44.pdf

In the MTJV001 hole, the JV reported 19m of heavily disseminated fluid-altered ultramafics which some may link to a hydrothermal mineral system being present in the Mount Thirsty area.

Kind regards OldGeo

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You may be right Oldgeo that one explanation is the SEDEX model in synsedimentary formation. I'm probably a little biased to epigenetic formation in often looking at gold mineralisation from hydrothermal pulses often precipitating in carbonaceous sediments. Some evidence of the fluid altered ultramafics may point more to the VMS model. It could be both!