Weolyu Gold & Silver Project

Introduction

The Weolyu Project is an historic underground mine that exploited epithermal style gold-silver (+germanium) mineralisation on several structures. The bulk of historical mining occurred on the north side of the river, referred to as Weolyu North. The south side of the river is referred to as Weolyu South and is some 200m+ higher in elevation than Weolyu North.

Recent Exploration

Very little previous work had been undertaken at the Weolyu Project prior to SAU’s acquisition of the project. SAU undertook two programs of surface mapping and sampling in 2017 which highlighted the prospectivity of the area (Figure 1).

Initial scout drilling was undertaken in December 2017. The drilling program successfully intersected high-grade gold and silver bearing, banded, low-sulfidation, epithermal quartz veins at the Surprise, Moonlight and Summit vein systems (Table 1).Unfortunately this drilling was conducted in steep, difficult-to-access terrain with the topography limiting optimal drill targeting of veins and resulting in acute drill traces to the targets.

Table 1: Weolyu Diamond drill program best intercepts on Summit and Moonlight veins.

Hole ID

From

(m)

Interval

(m)

Au

(g/t)

Ag

(g/t)

Au.eq

(g/t) #

Target

WUDD005

169.94

8.54

0.22

3.57

0.27

Summit Vein Zone

WUDD006

222.40

2.47

2.36

37.64

2.90

Summit Vein Zone

including:

222.40

0.70

3.19

64.60

4.11

Summit Vein Zone


231.40

0.30

21.10

49.10

21.80

Summit Vein Zone

WUDD007

152.90

3.58

4.80

129.10

6.64

Moonlight Vein Zone


165.70

0.92

13.55

447.38

19.94

Moonlight Vein Zone

including:

166.10

0.30

35.00

1,110.00

50.86

Moonlight Vein Zone

All interval widths are downhole widths, unless otherwise stated.

Figure 1: Weolyu South project geology and surface sampling.

A second phase of systematic underground channel sampling at its Weolyu was completed in September 2018 (Figure 2).

The sampling was conducted to infill and extended previous sample lines and also as part of a QAQC program checking on assaying protocols.  The initial underground sampling results are presented in ASX Report on 20th December 2017 “High grade gold and silver results from new work on historic South Korean mine”.

A total of 18 new channel sample lines were taken as infill or extensional lines and a further 29 lines were re-assayed for 34 samples, from coarse rejects retained from the first round. New samples were collected from three horizons along the historical drives (Figure 2).

The results from the new channel lines are highlight in Table 2. The results of the new sampling have continued to produce excellent high gold and silver results associated with the three currently defined pods.

Table 2. Weolyu top ten significant channel sample results.

Line ID

Max Width (m)

Interval (m)

Au (g/t)

Ag (g/t)

Au (gm)

FS330N_014

1.35

0.4

32.80

764.0

13.1

FS330N_013

1.1

0.45

30.00

1,280.0

13.5

FS330S_006

1.05

0.55

28.90

1,350.0

15.9

FS310N_002

1.5

0.7

21.80

469.0

15.3

FS310N_019

1.62

0.34

15.07

272.6

5.1

FS330N_001

1.8

0.5

10.85

503.0

5.4

FS310N_001

1.6

0.55

9.94

181.0

5.5

FS330S_001

0.9

0.6

8.84

501.5

5.3

FS310S_001

1.6

1.12

8.70

222.4

9.7

FS310N_029

1.45

0.46

8.40

197.0

3.9


Future Plans

Southern Gold is highly encouraged by the results that have been achieved at Weolyu. Significant depth and strike potential on high grade epithermal veins of meter scale widths is significant and this style of mineralisation is typically amenable to selective underground mining.

Figure 2: Stylised long section of Weolyu South old workings and sampling with interpreted plunging mineralised shoots open at depth.

A program of underground drilling is scheduled for the first half of 2020 to test for up-dip and down-dip extensions of mineralisation within the three main ore shoots at Cavers adit (Figure 2). The Weolyu Project preparation is well underway with improved road access to allow mobilisation of drilling equipment and contractor.

The initial drilling will be undertaken using a MetreEater pneumatic drill rig coring with conventional LTK60 rods that will produce core with a 44mm diameter (compared with nominal NQ size of 47mm).  The MetreEater diamond rig was selected due to its portability, pneumatic powered and ability to fit into the small profile historic old workings.  The aim of this initial program is to provide ’proof of concept’ of drilling by firstly targeting the Weolyu Surprise vein from surface, adjacent to the 330 East Adit, then from within the old workings on the 330 Level development, targeting the Mystery vein (Figure 3).


Figure 3: Proposed drilling program for the initial MetreEater program at Weolyu.  The surface location at ‘Lunchbox Pad’ was determined to allow drilling operations to be field tested for operating at other project locations

Technical Description

The primary aim of the Weolyu exploration programme was to develop a fuller understanding of the geological and structural controls that govern the distribution and extent of quartz vein-hosted Intermediate- to Low-Sulfidation (IS to LS) epithermal gold-silver mineralisation at Weolyu. This has successfully allowed the team to successfully predict or identify vein extensions, new vein zones and prospective trends through mapping out of exposed vein zones, host lithological unit contacts, important controlling faults, and alteration envelopes. The sampling programme has provided critical quartz vein textural information and data relating to gold-silver mineralisation tenor, depth of erosion and therefore down-dip exploration potential.

The veins identified at Weolyu South are characterised by polyphasal quartz-sulfide textures, typified by complex colloform quartz-adularia-sulfide-silver sulfosalt banding and quartz sulfide re-healed hydraulic brecciation, with common quartz pseudomorphs after bladed calcite (Figure 4). This is indicative of extensive boiling and confirms Weolyu South as an excellent target for potentially economic gold-silver mineralisation, possibly commencing at or near surface. 

Figure 4: Examples of vein textures from the Weolyu mapping and sampling programs in 2017.

The potential exists for significantly elevated grades at lower relative elevations, and the amount of vertical relief (Figure 2) indicates the degree of erosion is muted at Weolyu South compared to the north. This implies significant potential exists to discover elevated gold and silver grades at depth at the critical boiling zones.

Mineralised systems

Au and Ag mineralisation recorded in drilling was within LS epithermal veining. These multiphase systems had been variably reactivated and erratically overprinted by multiphase silicified breccias and veining. Below (Figure 5) are three examples of the characteristic mineralised vein systems found within the Weolyu mine to date.

Multiphase Epithermal colloform and late fluorite veins


Sulphidic Leader Veins
Hydrothermal rehealed breccias

Figure 5: Details of mineralised vein types from 2017 drilling.

Alteration

The surrounding vein-wall rock and footwall alteration is characterised by quartz + sericite + illite + chlorite +/- carbonate zone. These appear to be laterally zoned from structures and veins. When identified should be logged in detail in future drilling/mapping, as they are a usually a vector towards mineralisation (Figure 6).

Figure 6: Note the pale second half of core showing a surrounding pale sericite + illite alteration to veining. This is a typical alteration scenario found proximal to epithermal veining at Weolyu.