Magnetic Resources NL (ASX: MAU) has announced a positive update from its Hawks Nest 9 (HN9) project in Mertondale Region, Leonora, WA.
The company reported that an extensive interpretation of a detailed 50m spaced 124-line km ground magnetic survey covering HN9 has defined 20km of subsurface porphyry units.
The Hawks Nest 9 (HN9) project is situated on exploration Licence E38/3127 and has a 2.1km-long mineralised sheared porphyry target. The project is located 15km NW of the Granny Smith Operations owned by Gold Fields Australia Pty Ltd and 10km NE of the Jupiter Operations owned by Dacian Gold Ltd.
The 2.1km target has shallow gold mineralisation within sheared porphyry and porphyry/mafic contacts and lies in a favourable position within the Mt Margaret anticline fold hinge zone.
Ground magnetic survey interpretation
The company announced that an extensive interpretation of a detailed 50m spaced 124-line km ground magnetic survey covering HN9 has defined 20km of subsurface porphyry units.
MAU reported that within the 3km long mineralised gold zone envelope, there are 6km of interpreted porphyry units.
The company said that the area that has the most thickened gold mineralised porphyry, which are up to 70m thick in the southern part of the 3km mineralised zone have a distinct magnetic low signature. These negative magnetic zones are effectively outlining the subsurface thickened porphyries some of which are expected to be mineralised and are high priority targets.
It can also be assumed that the areas within the 3km long gold zone envelope have only been partially tested as the drilling was testing the near surface shallowly dipping porphyries within the first 50m and more than likely have missed other potential thickened porphyries, which can be found down to at least 100m depth.
Deeper drill programme
The company reported that a deeper drill programme of 17 holes totaling 1460m (averaging 85m) is designed to outline and define the strike extent, thickness and width of the thickened porphyry mineralised area where 12 NE trending interpreted porphyry units are located.
MAU said that within this zone, some of the thickened intercepts include 20m at 0.67g/t from 52m in MHNRC582 and 16m at 12.46g/t from 96m in MHNRC582, 28m at 0.645g/t from 4m in hole MHNRC497, 57m at 0.5g/t from 13m and 32m at 0.68g/t from 51m in MHNRC541, and 14m at 0.7 g/t from 25m in MHNRC179.
It may be noted that MHNRC582 had reported exceptional high-grade result of 4m at 49g/t from 108m earlier.
The company said that these thickened mineralised intersections correlate with three of the twelve interpreted units.
Many shallow intersections
The company said that there are many new shallow intersections with a total of 351 intersections (ranging from 1 to 9m) greater than 0.5g/t Au, which includes 162 greater than 1g/t Au, 57 greater than 2g/t Au, 27 greater than 3g/t Au and 21 greater than 4g/t Au. It should be noted that most of the intersections are very shallow and within the first 50m of the surface and are within the 3km gold zone.
Porphyries outside gold zone envelope
MAU reported that there are 14km in strike length of interpreted porphyries outside the 3km long gold zone, which only contains 6km of interpreted porphyries.
The company said that a number of these are planned for drill testing and the drill traces. Some of these interpreted porphyries are within anomalous soil geochemical areas and have not been previously drill tested.
MAU reported that there are 24 holes totaling 1870m (averaging 78m) designed to ascertain the nature and potential extent of any gold mineralisation outside the known gold areas within these interpreted porphyries and their mafic contacts.
Survey extended to Lady Julie area
The company reported that the 50m spaced 124-line km detailed ground magnetic survey that covers HN9 is being extended mainly to the east and will cover the Lady Julie area where an addition 230-line km survey is planned shortly.
This is intended to look for subsurface porphyries especially over areas that already have porphyry units drilled recently within the northern part of the Lady Julie area.
The company said that an additional 200 soil samples will also be taken in areas where previous sampling was too widely spaced in areas where porphyry units have been interpreted outside the 3km gold mineralised zone.
New thickened silicified porphyry
MAU reported that in the southern part of HN9 there is a distinct bend in the 3km long shear zone from SSE to SSW and there is a considerable thickening of the mineralised zone within an altered silicified porphyry.
The company said that this thickened porphyry is so far delineated over a 400m strike length, is open and plunges shallowly to the NNE, and dramatically thickens from commonly 2-5m up to 10-70m.
This thickened silicified porphyry crosscuts the NNW-trending near-surface flat-dipping mineralisation and may represent a blowout zone at the intersection of the NNW shear zone with NE trending porphyries and dolerites, where two separate porphyry shallow dipping zones coalesce and thicken.
The company said that further investigation of the extension to the 3km shear is being investigated to the north and south examining existing geology and ground magnetics carried out in these areas.
Three zones recognised, potential for deeper mineralisation
The company said that there are now three discernable mineralised zones recognised that mostly dip shallowly around 20-30° to the east within the sheared porphyry and sheared mafic/porphyry contacts. Previously there was only one mineralised zone recognised.
MAU said that the newly discovered multiple shallow dipping extensive zones at HN9 are a potential indicator for deeper mineralisation because all the numerous nearby large deposits in the region including Wallaby (7Moz), Sunrise Dam (10Moz) and Jupiter (1.3Moz) have persistent internal shallow-dipping mineralised lodes that are often called shear zones, which are ubiquitous throughout these deposits and have been defined down to 1500m depth at the Wallaby deposit.
In addition, many discoveries in recent times have been made by drilling below 100m because the historical drilling was far too shallow. At HN9 the average hole depth is only 46m providing tremendous scope for upside potential. In addition, the length of the 3km mineralised shear zone is like the length of the large Jupiter, Wallaby and Sunrise Dam Deposits.
The company reported that further deeper drilling will be planned to follow up results from deeper intersections with 41 holes totaling 3,330m at HN9.
MAU said that a 230-line km ground magnetic survey and a 200 soil sampling programme is planned both at HN9 and Lady Julie.
MAU’s Managing Director George Sakalidis commented: “With the Australian gold price at record levels of $2,518 the HN9 Project being only 15km NW of the Granny Smith Operations owned by Gold Fields Australia Pty Ltd and only 10km NE of the Jupiter Operations owned by Dacian Gold Ltd at Laverton, WA, is shaping up and has potential for a large-scale shallow deposit.
This significant 3km mineralised zone is so far defined by 465 RC holes totaling 20,484m is coherent and is not closed off to the north or south or at depth and a new thickened mineralised porphyry zone is also open in both directions and is being drill tested over a 500m length.
The discovery of a thick mineralised porphyry zone up to 70m thick and an outstanding intersection of 16m at 12.5g/t from 96m including 4m at 49g/t from 104m in MHNRC582 augers well for the potential NE extension of this thickened mineralised zone to the NE.
Importantly the recognition that the ground magnetics uniquely defines the thickened mineralised porphyry down to at least 100m depth is a fantastic tool to find other similar zones both within the existing 3km mineralised zone and outside this zone where there are respectively 6km and 14km of subsurface porphyry targets interpreted which are currently being investigated with 41 holes totaling 3,330m.
Also extending the ground magnetic survey over the Lady Julie area will allow the subsurface mapping in areas where there is known mineralised porphyry intersections closer to surface.”