Highlights:
- On 16 July 2018 ASD-1 was at a depth of 1225.5 metres and within an intermediate-felsic intrusive (diorite – granodiorite) (Figure 1).
- The diorite-granodiorite was entered into at a depth 644.4 metres and the change in geology from Hardey Formation at such a shallow depth was unexpected, with alteration, bleaching and a number of quartz and pegmatitic veins now being observed.
- The intersection of the granodiorite at a downhole depth of 644.5 metres and the resulting relative level above sea level, means that Artemisis ~180m higher than at Munni Munni as observed in MMD178 (Figure 1).
- This means that the interpreted basin deepening to the south of Munni Munni gabbro is incorrect and it is possible that the Fortescue Basin topography (when sediments were emplaced) is undulating and therefore ia fertile for trap sites and areas where mafic rich conglomerates can accumulate with detrital gold.
- Further analysis of the Felsic Intrusive (diorite-granodiorite) will be ongoing with work by GSWA and CSIRO.
ASD-1 is planned for a vertical depth of +3,300m and designed to test the many rock sequences in the Pilbara Basin from surface and deep into the basement’s geology. These deeper rock sequences were interpreted or inferred to exist, based on very sparse data. This surface and shallow data does not explain observed surface mineralisation of diamonds, cobalt, zinc, lead and gold.
What Artemis has defined at this early stage is very valuable as it shows the basement (hard rock geology) is undulating and actually dips to the north from ASD-1. The sediments (now rock) have filled in the topography that existed, which would have been hills, valleys, crevices. This means there are trap sites for mafic conglomerates in a multitude of possible locations, like between ASD-1 and Munni Munni (Figure 2).
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