Butcherbird Shear/Premium Lode
Background
The Butcherbird Shear is located 50-70m to the east of existing underground mine development on the Cascade Lode. The Swan Premium Lode is a mineralised, north-striking, steeply east dipping (60-70 degrees) conjugate vein set emanating from a broader, north-striking, steeply west dipping shear structure (Butcherbird Shear).
The Butcherbird Shear and Swan Premium Lode are not well-defined structures with sharp margins. Rather, they are zones of silica (quartz) flooding along ill-defined, pre-existing structures. Variability in both quartz flooding and gold grade within these zones is high. This observation is consistent with historical accounts of underground exploration and mining at Swan Bitter and Butcherbird.
High-grade underground Mineral Resources at the Swan Premium Lode deposit currently total 85,800oz of gold. In early 2018, the Company undertook a reinterpretation of the geological controls on high-grade mineralisation in the Swan Premium Lode and Butcherbird Shear at the north end of the Swan system, which indicated the potential to significantly increase the underground Mineral Resources in this area with additional drilling.
Highlights
- Assay results undertaken during the September 2018 Quarter first-pass drill program to test the Butcherbird Shear and Premium Lode included:
- 8.0m @ 19.7g/t Au from 297.0m in SBDD080 (previously reported);
- 6.6m @ 10.9g/t Au from 265.9m in SBDD076 (previously reported);
- 5.0m @ 10.6g/t Au from 257.0m in SBDD073 (previously reported);
- 6.0m @ 7.9g/t Au from 134.0m in SBDD076 (previously reported);
- 2.2m @ 9.6g/t Au from 128.55m in SBDD077 (previously reported);
- 3.0m @ 9.8g/t Au from 148.9m in SBDD080 (previously reported);
- 1.7m @ 9.7g/t Au from 122.0m in SBDD079 (new result); and
- 1.0m @ 12.6g/t Au from 232.0m in SBDD079 (new result).
- Follow-up drilling to test the extent and continuity of the thick, high-grade gold results on the Butcherbird Shear intersected in holes SBDD073, SBDD076 and SBDD080 is planned
As reported in the Company’s Announcement dated 7 July 2018, Horizon undertook a reinterpretation of the geological controls on high-grade gold mineralisation in the Premium Lode and Butcherbird Shear at the northern end of the Swan system. This reinterpretation highlighted the potential to significantly increase the underground Mineral Resources in this area with additional exploration drilling.
Following the geological reinterpretation, the Company estimated Exploration Targets of between 30,000oz to 100,000oz contained gold for the Premium Lode and 270,000oz to 800,000oz contained gold for the Butcherbird Shear.
An initial diamond drill program of 12 holes totalling 4,897 drill metres on the Premium Lode and Butcherbird Shear Exploration Targets commenced in late June 2018 and was completed on 22 August 2018. The aim of the program was to assess the validity of the Exploration Targets by drilling a broad spread of holes to test and support the predicted thickness and grade of the models in those areas.
Figure 1: Long section looking west showing historical and new drill hole pierce points testing the Butcherbird Shear and Premium Lode.
Figure 2: Cross section 6983780N looking north showing historical and new drilling intercepts on the Butcherbird Shear and Premium Lode
Zones of quartz flooding with minor sulphide mineralisation were intersected at the anticipated target depth in most holes. True widths of the quartz flood zones intersected in the current program are estimated to be up to 5 metres.
In addition to the intercepts interpreted to be on the Butcherbird Shear, several other unexpected quartz-sulphide structures were intersected. At this stage the Company is unable to correlate these structures with the known lodes and is therefore uncertain of their economic significance.
Gold assay results were received for holes SBDD075, 076, 077, 078 and 080. Significant assay results interpreted to reflect the Butcherbird Shear include:
- 8.0m @ 19.7g/t Au from 297.0m in SBDD080;
- 6.6m @ 10.9g/t Au from 265.9m in SBDD076; and
- 5.0m @ 10.6g/t Au from 257.0m in SBDD073.
In addition to these interpreted Butcherbird Shear intercepts, several other unexpected quartz-sulphide structures were intersected, including:
- 0.8m @ 17.4g/t Au from 132.0m in SBDD075;
- 6.0m @ 7.9g/t Au from 134.0m in SBDD076;
- 2.2m @ 9.6g/t Au from 128.55m in SBDD077; and
- 3.0m @ 9.8g/t Au from 148.9m in SBDD080.
Photograph of mineralisation in hole SBDD073 with individual 1 metre gold assays shown in red.
Discussion of Results
Zones of quartz flooding with minor sulphide mineralisation were intersected at the anticipated target depths in most holes. True widths of the quartz flood zones intersected in the current program are estimated to be up to 5 metres. Together with the assays received so far, the results are interpreted to be supportive of the modelled Exploration Targets.
For holes SBDD073, SBDD076 and SBDD080, intersected thicknesses and gold grades exceed the parameters used to estimate the Butcherbird Shear Exploration Target.
The Company notes that the gold mineralisation in the Swan system is highly variable and that correlation of high gold grades, even between closely-spaced drill holes, can be difficult. For this reason, the Company urges caution when considering the economic significance of the results obtained to date.
Follow Up Work Program
The Company is highly encouraged by the results of the initial program. As is apparent from the long section in Figure 3, there are very few drill holes in the vicinity of holes SBDD076 and SBDD080. Diamond drilling to infill this area is planned as a priority once all results of the current program have been received and a new and more comprehensive evaluation of the economic significance of the results is completed.
It is important to note that in addition to the interpreted Butcherbird Shear intercepts, several other unexpected quartz-sulphide structures were intersected. At this early stage and until all assay results have been received, the Company is unable to correlate these structures with the known lodes and is therefore uncertain of their economic significance.
The Company plans to provide a further update including a discussion of any material changes to the potential scale or quality of the Exploration Targets resulting from the initial exploration drilling program.
Figure 3: Long section looking west showing historical and new drill hole pierce points testing
the Butcherbird Shear and Premium Lode
