Regional Exploration

Lake Mackay Joint Venture


IGO is in an exploration alliance with ABM Resources NL (ASX: ABU) under which it can earn a 70% interest in a portfolio of tenements in the Lake Mackay region in the Northern Territory.

The Lake Mackay Project is located 400km northwest of Alice Springs, adjacent to the Western Australian border, and includes 7,200 square kilometres of exploration licences and 12,130 square kilometres of exploration licence applications, including recent applications in the DuFaur area. The area includes sparsely explored Proterozoic age metasediments intruded by granitic and mafic rocks beneath varying thickness of aeolian sand cover and is considered prospective for gold, base metals and nickel sulphide mineralisation.

The exploration approach is to initially blanket the project area with systematic high quality, low detection limit surface sampling to identify the geochemical signature potentially caused by large mineralised systems beneath shallow cover.

During FY2015 IGO collected 5,128 first pass reconnaissance samples and 3,505 infill samples, which together with sampling undertaken in FY2014, completes the geochemical coverage of the project area.
In Q3 2015 an AC program comprising 94 holes (3,216m) was completed in the southern part of the project, testing six gold and multi-element surface sample anomalies located within the Du Faur Project area (EL24915) and one gold target (Windermere South) located on EL27780.

This work returned a number of significant precious and base metal intercepts at the Bumblebee Prospect,together with lower order gold intercepts on the Prowl and Springer prospects, all located within EL24915 some 400km west of Alice Springs. 

The Bumblebee Prospect consists of a multi-element soil geochemistry anomaly that strikes east-west for over 1km. The peak of the soil geochemistry anomaly is coincident with a window through the transported sand-dune sediments and it is possible that anomalism extends under aeolian sand cover.

A total of 11 holes (578m) were drilled on nominal 25m spacings on two north-south traverses 200m apart to test the soil geochemical anomaly. Mineralisation was intersected on one drill section which indicates a southerly dipping mineralised zone within an east-west striking structure. Further work is required to establish the extents and geometry of this mineralised zone.

Significant drill results from the program (downhole width) include:

  • 2m @ 1.3g/t Au, 34.6g/t Ag, 7.0% Cu, 1.6% Zn, 1.3% Pb and 0.09% Co from 29m (oxide)
  • 7m @ 3.3g/t Au, 37.7g/t Ag, 3.2% Cu, 1.3% Zn, 0.9% Pb and 0.08% Co from 35m (supergene)
  • 5m @ 2.4g/t Au, 12.4g/t Ag, 1.4% Cu, 1.0% Zn, 0.2% Pb and 0.1% Co from 56m (fresh rock)

The oxide zone mineralogy includes malachite, azurite and chrysocolla (secondary copper oxide minerals) with native copper in the supergene zone. In the fresh rock, minerals observed include chalcopyrite (copper sulphide), pyrite (iron sulphide) and magnetite (iron oxide).

The combination of the multi-element metal association, the high-grade metamorphic rocks and presence of magnetite is similar to distal signatures of Cloncurry-style iron oxide copper gold (IOCG) deposits (e.g Ernest Henry or Osborne copper-gold mines in Queensland). However, further work is required to form a coherent metallogenic model for this region and this interpretation may change.

The next steps at Bumblebee include an aeromagnetic survey to identify prospective structures and iron oxide alteration; additional surface geochemical sampling, ground-based electromagnetic techniques for targeting massive or disseminated sulphide mineralisation; along with detailed mapping and further drilling.

On 22 September, IGO and ABM Resources Ltd (ABM) (as Joint Farminee) entered into a Farm-in and Joint Venture Agreement with Castile Resources Pty Ltd (Castille) over ELA29748, located on the northern and western margin of EL24915.  The agreement gives IGO and ABM the right to earn a 51% interest (divided 70/30 respectively) in ELA29748 by spending a total of $600,000 over a three year period.

Lake Mackay Project - Location Map over Gravity Image


Bryah Basin Joint Venture


IGO is in an exploration alliance with Alchemy Resources Limited (ASX: ALY) under which IGO can earn a 70% - 80% interest (excluding iron ore) in ALY’s Bryah Basin portfolio of tenements. The Bryah Basin JV tenure is situated approximately 40km west along strike from the DeGrussa Cu-Au VMS deposit currently being mined by Sandfire Resources Ltd and covers the same prospective Narracoota Volcanic – Karaluni Formation host stratigraphy. The IGO exploration team has extensive VMS exploration and discovery experience through its Jaguar and Stockman projects and is applying similar exploration techniques developed at these projects to the exploration of the Bryah Basin JV Project.

A full data review has been completed with a specific focus on determining those areas along the prospective contact that had not been fully or effectively tested by past exploration. Following this review, Moving-Loop Electromagnetic (MLEM) and broad spaced AC geochemical programs were completed across priority areas to identify conductors and/ geochemical responses potentially representing buried massive sulphide mineralisation. This work highlighted the Neptune prospect, comprising a strong multi-element (Au-Cu-Ag) geochemical anomaly with semi-coincident MLEM conductors as a high priority for follow-up.

During Q3 2015 IGO completed RC/Diamond drilling at the Neptune Prospect testing a 2.5km long multi-element VMS pathfinder anomalism at the prospective basal contact of the Narracoota Formation and the upper part of underlying Karalundi Formation, interpreted to be the DeGrussa ore horizon. These zones of geochemical anomalism are semi-coincident with several linear electromagnetic (EM) conductors returned from MLEM surveys.

The program of five RC holes and three RC/diamond tail holes, drilled on five sections nominally 500 metres apart, commenced in late June 2015 and was completed in late August 2015. The drilling targeted mineralisation at vertical depths of between 200 and 400m along 2km of strike of the prospective zone. Each of the RC/diamond holes used RC drilling to pre-collar to depths of approximately 150m, and cored to drill-hole completion. One of the RC holes, 15BRRC001DW1, was completed with a diamond drill-hole wedge. The diamond component of the drilling program was funded in part from a grant from the WA Government Exploration Incentive Scheme Co-funded Drilling Initiative.

Bryah Basin joint venture tenure
 Bryah Basin Project - Tenement Location Plan over Geology and Aeromagnetics

Drilling intersected zones of disseminated, blebby and stringer-style, pyrite-dominated sulphide mineralisation at several stratigraphic horizons within the Karalundi sedimentary-dominated sequence close to the contact with the overlying mafic (volcanic-dominated Narracoota sequence).

To date, assays have been received for 4m composite samples taken down each of the RC holes and RC pre-collars of diamond holes.  The results indicate multiple mineralised horizons with strong copper and/or gold anomalism within the prospective Narracoota – Karalundi volcano-sedimentary sequence.

The diamond drilling has provided important stratigraphic and structural information in an area with no previous core-drilling. Follow-up DHEM will also provide constraints on any off-hole EM conductors in the near vicinity.

The size and amplitude of the geochemical and geophysical anomalism is indicative of the marginal zone of a VMS system. The current density of drilling at Neptune (500m between sections), is insufficient to provide a definitive test of the prospect.  Recommendations on further work will be made once all diamond assays have been received and integrated with other data sets from the area.


IGO is earning a 70%-80% interest in the Darlot project located approximately 60km north and along-strike from IGO’s Jaguar Project covering similar volcanic stratigraphy to the Jaguar Project. The Darlot Project has strategic value to IGO as any base metals discoveries are potentially within economically viable trucking distance of its Jaguar processing facility.


The SCJV comprises a series of tenements on the eastern flank of the Tropicana JV that are being explored for magmatic Ni-Cu mineralisation. A combination of exploration techniques including soil geochemistry, MLEM, gravity and AC drilling are being employed according to the target expression and local regolith conditions. Programs were completed at the Rising Dragon, Cobra and Vesper Prospects during the quarter.

Last quarter the first phase of a broad spaced AC geochemical drilling program was completed over 217km2 of the interpreted Salt Creek Complex.  Assays were received early this quarter and highlighted 4 areas anomalous in nickel and copper geochemistry, the largest of which is referred to as the Cobra Prospect.  Subsequent 500m x 200m spaced infill AC drilling confirmed nickel-copper anomalism at the Cobra and Cobra North Prospects. Both prospects have now been earmarked for MLEM surveying in the December 2015 to test for massive sulphide mineralisation.

The Rising Dragon Prospect comprises elevated Ni and Cu geochemistry intercepted by historic Tropicana JV regional AC drilling on the margin of a large interpreted gabbroic intrusive. During the quarter IGO completed three 100m spaced AC traverses over the area of elevated geochemistry.  A series of regional AC holes on 1km centres were also drilled to define the margins of the gabbro.  Holes over the area of elevated geochemistry intersected a zone of disseminated magmatic sulphides approximately 100m wide over a strike of approximately 250m. A MLEM survey covering tested an area of 7.3km2 centred over the mineralised drill holes for evidence of massive sulphide mineralisation.  A series of low conductance plates were identified but there was no response indicative of massive sulphide at shallow depths. The potential of the remainder of the Rising Dragon Gabbro is yet to be tested by MLEM or closer spaced drilling and will be assessed over the coming quarter.

The Vesper prospect is located to the far east of the SCJV within the Fraser Range geological province, the same mafic-ultramafc intrusive dominated geological domain that is host to the Nova-Bollinger orebody. A MLEM survey was undertaken over a linear aeromagnetic feature, interpreted to be a discrete mafic/ultramafic intrusion, to test for conductors indicative of massive sulphides that could be tested with RC drilling. The survey identified a shallow conductor, interpreted to represent deeper weathering of the intrusion but did not locate any conductors consistent with massive sulphides.

Salt Creek Joint Venture - Tenement Location Plan over Aeromagnetic Image

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