Bourke Gold Project
The Bourke Gold Project is positioned in the Southern Thomson Orogen, in an area that has not received systematic modern exploration techniques, primarily due to the thick cover sequences of the Eromanga Basin. The project area is targeted at the intersection of two major continental scale structures, termed the G3 and G7 lineaments (Figure 1). These lineaments represent continental scale structural corridors and show a broad relationship with major ore deposits as shown in Figure 1.
The Bourke Gold Project covers approximately 2800km2 of tenure and is 100% owned by Nimrod. While the majority of the exploration tenure is covered by a 200-400m thick package of Mesozoic Eromanga Basin sediments, an area of anomalously shallow Paleozoic basement has been identified in the north western sector of the tenement portfolio, where the depth to basement varies between 40-100m over a 30km long corridor (Figure 2).
The Springvale Dome Target is situated at the north eastern sector of this 30km long exploration corridor and is considered prospective for orogenic gold mineralisation based on:
- Nimrod diamond drilling proximal to the Springvale Dome Target has identified narrow zones of elevated gold associated with carbonate veined and deformed basalt – TDH-16: 2m @ 131ppb Au from 460m.
- Detailed aeromagnetic and ground gravity surveys implemented by the Company has identified an area of structural complexity, namely the intersection of a major northeast trending structure termed the Yalambie Fault and a major northwest trending structure termed the Congararra Fault Zone. The Yalambie and Congararra Faults are thought to represent trans-lithospheric faults i.e.: associated with the G3 and G7 lineaments and therefore may act as the necessary conduits for migration of volatiles and gold rich fluids derived from the upper mantle.
- Antiformal culminations recognised in the magnetic stratigraphy and second order structures such as WNW splays are conceptual camp scale sites for gold deposition.
Furthermore, a number of discrete, bullseye magnetic targets have been detected in the recently completed aeromagnetics survey and are spatially coincident with the 30km long exploration corridor (Figure 2). These magnetic targets are comparable to magnetic bullseye features associated with Cobar Style orebodies, such as the Endeavor Deposit (formally the Elura Mine), located 120km south of the project area. The Endeavor Deposit is a massive sulphide orebody with a global resource estimate of 27Mt @ 6.5% Zn, 3.7% Pb, 68g/t Ag and 0.2% Cu. Further work is required to develop these targets to the drill decision.
Given the target areas are under relatively shallow cover, the area is amenable to conventional exploration techniques. Planned exploration will consist of:
- Springvale Dome Target: geochemical drilling such as aircore (AC) drilling with gold, basemetal or pathfinder element anomalies refined with electrical geophysics and tested with deeper drilling such as reverse circulation (RC) or diamond drilling.
- Broader target corridor to be selectively sampled with Ultrafine soils to detect for gold and basemetal anomalism. Targets will be followed up with deeper drilling.
- Bullseye magnetic highs to be screened for conductive massive sulphide orebodies with a high powered ground electromagnetic survey. Conductors will be tested with RC or diamond drilling.