The Central Group has had variable degrees of exploration, with a number of areas requiring follow up work.
To date, the Central area contains a number of deposits including Nambi, Redcliffe and Westlode. All of these remain open at depth.
The Central area can be split into two halves:
In the northern part, the regolith profile is stripped with abundant outcrop. This allowed the early prospectors of the early 1900s to find the gold occurrences that culminated in the modern day Redcliffe, Nambi and Mesa open pits.
The southern half lies under transported and lateritic cover to depths of 10-15m in places. This has obscured the underlying rocks limiting effective exploration.
The level of exploration also varies from north to south. Extensive shallow RAB drilling in the northern portion around the Nambi, Redcliffe and Mesa open pits (mined in the early 1990s) has broadly outlined several mineralised trends which require follow-up drilling (Redcliffe East, Redcliffe South, Mesa West and Infinity).
Depth and strike extensions to high grade lodes at the Nambi, Redcliffe, Westlode and Mesa deposits are also priority targets.
The Mertondale Shear Zone can be 1-1.5km wide and is bounded by two mineralised shears, the Great Western and Mertondale Faults. Gold mineralisation discovered to date associated with the west bounding Great Western Fault is hosted within intermediate schists, felsic schists and black shales (eg. Redcliffe) whereas mineralisation along the eastern Mertondale Fault is associated with mafic schists and felsic porphyries.
In the south, wider spaced RAB drilling completed in the 1990s has identified a similar geological sequence of mafic, felsic and sedimentary rocks generally under cover. Depth of weathering is far greater than in the north, to depths of 70m. Some depletion has also occurred within the regolith profile to depths of 40-50m, suggesting that a lot of the earlier shallow RAB drilling to depths of 30-50m were ineffective. Some deeper holes at prospects like the ‘Hub’ did intersect anomalous gold in RAB drilling and require further work.
Interpretation of regional airborne magnetics shows the Mertondale Shear Zone within the Central area to be structurally complex with orientation changes in the greenstone belt together with swarms of late dolerite dykes. This structural signature is a prime region for gold mineralisation to form.
Central Zone
