Legend Mining Limited (ASX:LEG) will undertake reverse circulation (RC) drilling to test gravity and geochemistry targets identified in surveys that extended the footprint at Mawson prospect within the Rockford Project on WA’s Fraser Range.
A recently completed gravity survey has identified three high gravity anomalies with anomalous nickel-copper aircore geochemistry straddling these anomalies.
RC campaign scheduled
An RC drill campaign has been designed and scheduled by Legend to test a combination of these gravity and aircore geochemical targets.
Legend managing director Mark Wilson said: “The size, strength and location of these gravity highs between the two geochem anomalies makes this a very exciting feature of the Mawson story.
“The footprint that has now been interpreted, demonstrates the current extent of the large mineralised Mawson system.
“We have scheduled an RC drill program to commence as soon as possible, which is designed to provide the geology to help identify the source of the massive sulphide mineralisation which we have already discovered.”
Prospect locations at the Rockford Project.
Gravity survey completed
The Mawson gravity survey comprising 2,325 stations at 50 x 50-metre and 100 x 100-metre spacings covering 10.8 square kilometres has been completed and the data processed.
This was aimed at providing high-resolution data to better define the main 4mgal gravity high and to be used in conjunction with aircore drilling to assist deep drill targeting.
There are three discrete gravity highs within a larger 3-kilometre-long arcuate feature with elevated gravity response.
Gravity highs identified
A main southern gravity high has a N-S trend and is about 300 metres east of the nickel-copper sulphide mineralisation intersected in diamond drilling.
The two other gravity highs trend NE-SW and lie 650 metres and 1,100 metres respectively NE of the mineralisation.
Mawson gravity image with anomalous aircore drill holes.
2D gravity modelling of the three gravity highs indicates densities associated with mafic and ultramafic lithologies as the likely source and represent highly favourable nickel-copper host rocks.
Recent and historic aircore drilling at Mawson has defined two coherent nickel-copper anomalies which straddle these gravity highs.
The western anomaly relates directly to the sulphide mineralisation identified in diamond drilling, while the larger 1,100 metres x 200 metres eastern anomaly, which is open to the east, lies on the eastern and southeastern margin of the main gravity trend.
Legend expects that the deeper RC drilling through the metasediments/granulite into the gravity high will intersect prospective mafic/ultramafic intrusives.
Schematic section showing relationship between anomalous aircore drill holes, mafic/ultramafic intrusives and barren metasediments/granulite 'blanketing' the gravity high.
It is possible that this gravity high may represent the primary source of mineralisation identified in the Mawson diamond drilling to date.
Future programs
Apart from the RC drilling, other planned work at Mawson includes:
- Diamond drill testing Northeast Mawson conductors D13 and D15;
- Complete 200 x 200-metre aircore drilling program;
- LF-FLTEM surveys over Mawson D1 conductor following up offhole feature; and
- Ongoing regional MLTEM survey at South Mawson.