Nexus Minerals - Major Intrusive Related Alteration System Identified at Pinnacles
Nexus Minerals (ASX:NXM) has completed a Gradient Array IP Survey over the Pinnacles Project, highlighting coincident gravity and magnetic anomalies within the 'Pinnacles Corridor', a NNW tranding zone covering 2.5km x 600m. Further drilling is planned on priority targets.
- Recently completed IP geophysical program highlights “Pinnacles Corridor” and Pinnacles North anomalies
- Drill ready gold targets identified within “Pinnacles Corridor” and Pinnacles North anomalous areas – planning underway to allow priority drill testing
- Extensive coincident chargeability high and resistivity high anomaly identified over magnetic anomalies within the “Pinnacles Corridor” (GT1)
- The anomaly may be related to areas of disseminated sulphides (chargeability highs) and large zones of silicification (resistivity highs) – frequently associated with gold mineralisation
- The 1.5km x 250m north trending resistivity high and chargeability high anomaly exhibits the signature of a major intrusive related alteration system
- The resistivity high occurs within an extensive broader 2.5km x 600m north - north west trending zone of higher resistivity – prospective alteration
- IP survey also confirms resistivity high centered on Pinnacles North coincident gold / arsenic soil geochemical anomaly (GT2)
- Potential “repeat” of Pinnacles East style mineralisation is observed in a duplicate structural position, 200m south east of the Pinnacles East resource (GT3)
- Narrow north south coincident chargeability & resistivity high possibly representing deformed silicified black shale unit (GT4)
- The survey has highlighted the significant scope for regional gold exploration potential
Eastern Goldfields gold explorer, Nexus Minerals Limited (ASX: NXM) (Nexus or the Company) is pleased to announce the results of the recently completed Gradient Array Induced Polarisation (GAIP) geophysical survey conducted on the Pinnacles JV project in the eastern goldfields of Western Australia.
The GAIP survey, in conjunction with the previous aeromagnetic interpretation, has produced encouraging results highlighting the considerable regional exploration gold potential. The survey identified a broad zone of resistivity highs and in part chargeability highs with the highest coincident anomaly occurring directly over the previously identified aeromagnetic target within the “Pinnacles Corridor”.
Gradient Array IP Survey
The Gradient Array Induced Polarisation (GAIP) method is a geophysical method used in gold exploration and provides two forms of results, being Resistivity and Chargeability. Taking measurements involves use of a transmitter to generate a current, and a receiver to measure the resulting voltages. The Resistivity will use voltage and current measurements to calculate the resistivity of the rocks, while Chargeability will involve measuring the subsurface voltage response of some minerals at certain times after the current supply is switched off.
The method was selected as it allows a large area to be covered where the positions of anomalies are not well known, and also has the potential to identify zones of:
- Resistivity – highs representing potential silica alteration / quartz veining also often associated with gold mineralisation, and;
- Chargeability – highs representing the presence of sulphides (pyrite / arsenopyrite) often associated with gold mineralisation.
The Nexus gradient array IP survey was conducted over a 4km x 1km grid, with 200m spaced lines, tightened to 100m spacing over the Pinnacles East resource area for a total of 23 line kilometres. Recordings were taken at 25, 50 and 100m along the lines. The 100m data provided a reliable data set for this first pass survey, with the 50m and 25m data providing better delineation of structures, alteration and lithological distribution.
The GAIP survey has identified a number of local and regional features(Fig. 1 and 2 – 50m data shown):
- The resistivity data shows a broad north - north west trending 2.5km x 600m zone of increased resistivity, with a number of higher order anomalies within it.
- This broad resistivity zone contains coincident high order resistivity (up to 650 ohm.m) and chargeability (up to 40mV/V) anomalies (GT1 anomaly). Areas where these resistivity and chargeability anomalies coincide are considered excellent targets for gold mineralisation. These highs also coincide with previously identified aeromagnetic highs representing potential high level intrusions.
- Resistivity highs also occur along contact zones of magnetic / non-magnetic rock units, within the previously reported Pinnacles North 1.6km x 300m geochemical coincident gold (>15ppb) arsenic (>50ppm) anomaly, and beyond. These contact zone resistivity highs are interpreted to represent silicification of a black shale unit. This is highly prospective as this rock unit also hosts the Pinnacles East gold mineralisation (GT2 anomaly).
- Pinnacles East gold mineralisation is defined in the GAIP data by a weak but distinct resistivity anomaly co-incident with the current resource. A potential “repeat” of Pinnacles East style mineralisation is observed in a duplicate structural position, 200m south east of the Pinnacles East resource (GT3 anomaly).
- A narrow north south coincident chargeability & resistivity high possibly representing a deformed silicified black shale unit (GT4 anomaly).
- The chargeability high predominantly to the west of the shale/volcaniclastic unit contact (green dashed line on fig. 2) is likely to represent a graphitic black shale lithological unit. The presence of this graphitic unit is important, as with the correct structural and chemical factors it can aid in the deposition of gold.
The GAIP survey, in conjunction with the previous aeromagnetic interpretation, has produced encouraging results highlighting the considerable upside for the regional exploration gold potential - both within the Pinnacles JV tenement and the larger surrounding Pinnacles Regional tenement package.
Nexus is continuing to build up geological, structural and mineralisation information of the region with interpretation models being built and modified as new information is gathered and assessed.
Drill planning is now at an advanced stage for the further testing of the Pinnacles East resource area as well as regional targets recently identified.
Nexus Minerals Managing Director, Andy Tudor, said “This geophysical program, in conjunction with our other exploration activities, has provided very useful information that will assist us in drill targeting. The size and magnitude of the coincident resistivity and chargeability anomaly identified within the broader regional anomaly is very encouraging for the discovery of mineralisation associated with zones of silicification and/or sulphides. Drill planning is currently underway and we plan to test these anomalies as a matter of priority.”