PNX’s Yorke Peninsula tenement holding of approximately 1,200 square kilometres over 4 tenements (EL4031 Minlaton, EL5491 Koolywurtie, EL5196 Coonarie, and EL4983 Weaver Hill) is located on the eastern edge of the Gawler Craton within the ‘Olympic Domain’, a world class copper/gold province.

The Olympic Domain extends from the Yorke Peninsula in the south, to Prominent Hill in the north, and hosts the Hillside (337 Mt at 0.6% Cu, 0.14g/t Au), Moonta-Wallaroo (past production of >355,000t of Cu and 3.5t of Au ), Carapateena (800Mt at 0.8% Cu, 0.3g/t Au), Prominent Hill (178 Mt at 1.1% Cu, 0.7 g/t Au) and the giant Olympic Dam, (9570 Mt at 0.82% Cu, 0.26 kg/tU3O8, 0.31 g/t Au, 1.0 g/t Ag1) deposits (see below).


Figure 1 – Olympic Domain and PNX’s Yorke Peninsula tenure

The Company continues to seek a partner to assist in carrying out a comprehensive exploration over the Yorke Peninsula, following up on work done by the Company to date and the multiplicity of excellent targets that have been identified.

Exploration 2011-2014

In late 2011, the Company flew a VTEM (Versatile Time Domain Electromagnetic) survey over the northern portion of the Minlaton and Koolywurtie tenements.  In 2012 a ground gravity survey, conducted on a 100m x 50m east west grid configuration totaling approximately 4,500 stations, was conducted over selected areas on the same tenements.

This data was used to identify drill targets, of which 3 were selected with coincidental magnetic/gravity anomalies.

An initial drill program was completed in early 2012 where 6 diamond holes were drilled with encouraging results. This prompted a follow up drilling program in 2013.

2012 Drilling Program 

During the June 2012 quarter, the Company completed its first diamond drilling exploration program on the Yorke Peninsula, comprised of six holes totaling 1,331m. These holes were primarily designed to test three ‘stand out’ VTEM anomalies, whilst identifying possible favourable host lithologies and alteration assemblages that could vector future exploration toward copper-gold mineralisation.

Anomalous copper intervals over 400ppm are listed below in Table 1 and anomalous gold values over 0.1g/t are listed in Table 1b.

Table 1: Copper values greater than 400ppm (0.04%) with 100ppm cutoff

Hole ID From To Interval (m) Cu (ppm)*
PYD001 129.00 130.6 1.60 532
including 129.0 130.00 1.00 685
PYD001 151.0 153.00 2.00 430
including 151.0 152.00 1.00 513
PYD001 212.00 213.7 1.70 460
including 213.00 213.7 0.70 936
PYD002 No copper values greater than 400ppm
PYD003 100.90 101.4 0.50 469
PYD004 124.2 124.8 0.60 520
PYD005 114.1 114.3 0.2 759
PYD006 No copper values greater than 400ppm

*Copper determined by four acid digest followed by ICP-OES finish. QA/QC samples indicated acceptable analytical quality. Intersections are down hole lengths. True widths unknown. Based on drillholes samples background copper is approximately 79ppm.

Table 1b: Gold Values above 0.1g/t

Hole ID From To Interval (m) Au g/t*
PYD006 94.6 95.6 1.0 0.13

*Gold determined by aqua regia digestion followed by AA finish. QA/QC samples indicated acceptable analytical quality. Intersections are down hole lengths. True widths unknown.

The lithologies, style and intensity of alteration, and levels of sulphides intersected throughout all six drillholes confirmed the Company’s geological models and provided increased exploration confidence for vectoring to copper-gold mineralisation within PNX”s tenure.

From the three targets drilled (SGVT1, SGVT9, and NGVT56), three discrete geological and structural settings were recognised, each with the potential to host significant copper mineralisation. Each area hosted a different stratigraphic unit: Hiltaba Suite (SGVT9 PYD003-PYD004), Wallaroo Group (NGVT56 PYD005-PYD006) and possible Lincoln Complex (SGVT1 PYD001-PYD002), each with varying styles and intensity of alteration assemblages.

Discussion of Drill Results

The 6 holes drilled under this initial diamond drilling program covered only a very small area within the Company’s large highly prospective tenure on the Yorke Peninsula. They were the first diamond holes drilled since 1955 when 2 holes were drilled at Balgowan. Further, the program only tested 3 of the 29 VTEM and 13 3D magnetic and gravity targets.

The prospectivity of each of the three drill targets is confirmed by the intersection in all six diamond drillholes of the following positive ingredients for IOCG mineralisation:

  • favourable lithologies (Wallaroo Group and Hiltaba Suite intrusives);
  • anomalous copper values indicating copper in the system;
  • style and intensity of alteration (albite – haematite, biotite-magnetite pyrite-chalcopyrite, chlorite-quartz-haematite-k feldspar-pyrite – chalcopyrite);
  • brecciation; and
  • levels of sulphides (PYD005: pervasive disseminated pyrite 1-10% over 140m down hole length (visible estimates from 93.2m – 233.6m).

2013 Drilling Program

New targets at the Balgowan and Cross prospects were tested during a 3,074m, 100 hole aircore (AC) and slimline reverse circulation (RC) drilling program conducted in February/March 2013. Both areas are characterised by coincident geophysical anomalies consistent with the signature of IOCG mineralisation. Depth of cover above the prospective basement host rock ranged from 10m-30m allowing a significant number of holes to be drilled over a large area. The initial phase of drilling aimed to identify shallow secondary geochemical dispersion patterns associated with primary mineralisation, to confirm the source of the coincident geophysical anomalies, and to gain a greater understanding of the geochemistry in this environment.


Figure 2: Balgowan prospect: a) drillhole locations over gravity image; b) Copper assay grid c) Iron assay grid. White rings are geochemical and geophysical highs.


Anomalous copper was observed in all areas tested with the best results coming from the Cross Prospect. Here drilling defined elevated copper at the basement interface coincident with gravity and magnetic anomalies that may indicate primary mineralisation at depth (Figure 3).

The Balgowan prospect was drilled to delineate the lateral extend of the IOCG mineralisation intercepted in historic diamond drill holes DDH1 and DDH2 completed in 1955.  The recent drilling intercepted anomalous geochemistry in prospective rocks, including massively altered magnetite, biotite, calcsilicate metasomatitic rocks (containing high percentages of iron over a large area) which are possibly associated with a regional mineralising event (Figure 2). The alteration system identified is still untested at depth as the deepest drillhole (PYAC0039) was still within massive magnetite mineralisation at 100m downhole depth.

Overall, the results from this shallow drilling program were encouraging.  Prospective geology and geochemistry within a significant alteration system was identified together with a new area that has the potential for mineralisation at depth.