Gold Fields – 3D Seismic Discovers “Smoking Gun” In The Deep For Prolific Mineral System
Background
St Ives gold mine is situated in the well-endowed, mature region of Eastern Goldfields in Western Australia. Gold Fields mining company were looking to evaluate deeper targets as part of their near-mine exploration strategy. Two of the key targeting criteria is structure and lithology. Significant resource potential remains below current workings but increasing costs with depth required better geological definition for drill targeting.
“This Victory Dome had been recognised. What hadn’t been recognised was this feature immediately below 3.6Moz of gold. We drilled a 1700m hole into this. It turns out it is a bunch of porphyries, intense alteration and sulphide mineralisation. If you were in South America, you would get incredibly excited when you saw this. The 1700m hole – the last 1200m of that hole ran consistently over about 0.22gpt gold. So if ever there was a smoking gun for a system like this, this is it.”
Gary Snow, Vice President Exploration, Gold Fields. 2020 Diggers and Dealers Forum, Kalgoorlie.
Solution
HiSeis completed a 3D seismic survey (30km2) in 2017. Unique hard rock seismic processing and interpretation successfully illuminated geology several km below the mine. HiSeis innovative techniques (ROCK-MOD and SEISOMICS) were later applied to generate even more detail.
Outcomes
3D seismic effectively illuminated large scale geological structures several kilometers into the subsurface. Three main rock units were mapped across the entire dataset (ROCKMOD). A new large intrusive was discovered and a subsequent 1700m drill hole resulted in a 1200m intersection consistently over about 0.22gpt. This new insight has significant implications for the emplacement of gold at St Ives.
SEISOMICS automated geobody modelling was used to provide detailed 3D outline of intrusive bodies and alteration zones.
ROCK-MOD rock property modelling was used to map key lithologies within the St Ives 3D seismic.
