Jupiter is a conceptual copper-gold target with independent corroborative indicators from regional gravity, aeromagnetic and MT geophysical surveys.
Experienced geophysical contractor Haines Surveys has been engaged to carry out the survey, which will be completed within the next two months, subject to crew availability.
To assist with drill targeting
The survey work is expected to assist drill targeting at the prospect, which is southeast of the major Olympic Dam operations of BHP Group Ltd (ASX:BHP) and northwest of Broken Hill.
Havilah’s technical director Dr Chris Giles said, “Jupiter is an exciting copper-gold conceptual exploration play in a prospective geological setting with plenty of evidence for major fault or fracture systems from aeromagnetic data.
“Three independent geophysical indicators all point to roughly coincident features of interest in the vicinity of Jupiter.”
Havilah's projects and prospects in South Australia's northeast.
Circular gravity feature
During evaluation of publicly available data, a circular gravity feature was noted in some detailed SARIG data about 5 kilometres south of the MT survey line.
This positive gravity residual anomaly lies on a prominent NNW trending magnetic lineament, which may be indicative of a major fault structure.
Gravity measurements are influenced by the density of underlying rocks in relation to the Earth’s surface.
Hence at a given depth denser rocks, which can include metalliferous deposits or their host rocks, will generate a positive gravity anomaly or gravity high at surface.
Circular gravity features can sometimes indicate intrusive igneous rocks or a pipe-like alteration zone that can be host to mineralisation.
Useful targeting tool
While the source of this gravity feature is unknown at this stage, it does indicate the potential usefulness of gravity as a targeting tool in this region.
Accordingly, as an exploration objective, Havilah has decided to extend the detailed gravity survey northwards to beyond the MT survey line.
The aim is to determine whether the subtle gravity ridge detected in the public data continues to the north.
Area of planned detailed gravity survey over the Jupiter MT anomaly. Interpretation of earlier publicly available gravity data to the south of Jupiter revealed a circular gravity feature.
Giles added, “Our challenge is to refine those geophysical indicators down to a drilling target scale if possible, and the planned gravity survey will be important in helping us to achieve that.”
Jupiter was identified by Professor Graham Heinson and his team from the University of Adelaide during 2017 following collection and analysis of 2 kilometre-spaced MT readings.
Olympic Dam similarities
Notably, the volcanic rocks and associated granites in this part of the Curnamona Craton are almost identical in age and origin to those in the Gawler Craton that host the Olympic Dam deposit.
This point encouraged previous explorers like MMG and Newcrest in their quest for iron oxide copper gold (IOCG) deposits in this region.
MT is a geophysical method that relies on measuring the very small natural time variations of the Earth’s magnetic and electric fields to determine the electrical resistivity in the subsurface.
The method is able to distinguish zones of varying electrical conductivity in the earth’s crust to depths of more than 20 kilometres.
It is a powerful technique because it can potentially identify major conductive zones in the earth’s crust that could represent the feeder zones to large metal accumulations.