Legend Mining Limited (ASX:LEG) has identified multiple new fertile intrusions in a regional aircore and EM programmes as it prepares for an upcoming Octagonal seismic survey at the Rockford Project, Fraser Range, Western Australia.
The latest results from our 2022 regional programmes and interpretations detailed in the body of this announcement speaks to the prospectivity and untapped potential of the entire Rockford Project area,” Managing Director, Mr Mark Wilson, said.
“This potential is further enhanced by the fact that two of the four publicly disclosed occurrences of massive nickel-copper in the Fraser Range, being Mawson and Octagonal, are within the Rockford project.
“Our technical team and consultants are currently reviewing results as they come to hand from this years’ diamond drilling at Mawson, which will ultimately lead to a new interpretation of the Mawson seismic data. The new Mawson model and the first seismic model from Octagonal promise exciting diamond drill targets at both locations in 2023.”
Exploration activity continues across the Rockford Project with aircore drilling identifying new fertile NiCu intrusions, while innovative EM continues to identify new bedrock conductors.
Five of these areas have been identified through a combination of reconnaissance aircore drilling and innovative MLTEM. In addition, site preparations for the 3D seismic survey at Octagonal are underway, with the data collection phase scheduled for October 2022.
Aircore Drilling
A total of 161 aircore holes (RKAC1480-1640) for 13,047m have been completed year to date over selected areas within the greater Rockford Project.
This drilling is part of an extensive 30,000m regional aircore programme planned across the greater Rockford Project. The completed drilling was targeting a combination of aeromagnetic and gravity features interpreted to represent ultramafic and mafic intrusives within the same structural domain as Mawson.
This domain is characterised by an elevated gravity and low magnetic response which extends southwest and northeast of Mawson and has only been tested with limited aircore drilling to date. Newly identified Areas W, X, and Y are detailed below.
Area W
Area W was selected for first pass aircore drilling targeting a folded “eye” like feature in aeromagnetic data.
The drilling intersected anomalous nickel and copper associated with olivine bearing websterite in multiple drillholes, within a regional metasedimentary package. The assay result from RKAC1566 of 12m @ 0.1% Ni and 0.09% Cu from 58m in a favourable ultramafic host rock is an encouraging first pass result.
Geochemically, three wide-spaced aircore drillholes across Area W display the key indicator elements associated with fertile Ni-Cu intrusions when plotted against the fertile intrusion datasets of the Fraser Range including Nova, Mawson, and Octagonal.
Innovative high power MLTEM surveying over the area identified a deep, poorly constrained conductor located west south-west of the anomalous aircore holes. Follow up FLTEM surveying to better define the feature identified a conductor plate with modelled parameters of ~300m x 300m in size, with a conductance of 2,500-4,500S at a depth of 600-650m.
Further evaluation of this conductor and anomalous aircore geochemistry is planned.
Area X and Area Y
First pass aircore drilling was completed over Area X and Area Y, located five to 10km directly south-west of Mawson, targeting a combination of aeromagnetic and gravity features.
The drilling has intersected extensive ultramafic and mafic intrusives including olivine websterite and gabbronorite, visually similar to those which host Ni-Cu mineralisation at Mawson. Geochemistry supports the visual assessment that these identified intrusions plot on or proximal to prospective trends.
Given the wide-spaced nature of first pass aircore, these results are encouraging as early indications suggest a potential cluster of newly identified fertile NiCu intrusions. Infill aircore and high-power moving loop electromagnetic surveying is planned to further evaluate the Areas W, X, and Y.
EM Surveying
Following a review of regional aeromagnetic and gravity datasets, previous aircore drilling, and lithological domain mapping, 12 areas were selected for follow up with innovative high power electromagnetic surveying. Four of the 12 areas have been completed to date, with surveying currently underway at the fifth area.
Conductors have been identified at all four areas surveyed (see Table 2). This technique has proven successful in detecting conductive bodies beneath thick, conductive transported cover for Legend across the Rockford Project.
Conductors C and D
MLTEM follow up of elevated 2021 aircore geochemistry was completed over two areas in the north of the Rockford Project.
Conductors were identified at both areas and modelled as large, moderate strength features. These conductors, along with previously reported Conductors A and B, parallel the regional stratigraphic trend and are considered low priority areas for follow up work.
3D Seismic Survey
Planning of the 24km2 Octagonal 3D seismic survey continues, with Programme of Work approvals from DMIRS received and line clearing underway at time of writing.
The acquisition phase of the seismic survey is due to commence in October 2022.
Future Programmes
- Aircore drilling over selected areas ongoing
- Data analysis ongoing identifying new and advancing existing areas
- Octagonal 3D Seismic data acquisition scheduled for October 2022.
