BULGOLD Inc. press release
BULGOLD Discovers Epithermal Quartz Veins at Surface Within the Sinter Field on the Lutila Gold Project and Completes 2024 Drilling Programme
TSXV - TSX Venture Exchange · Gold · Silver · Antimony · Arsenic · Canada
TORONTO, Nov. 14, 2024 (GLOBE NEWSWIRE) -- BULGOLD Inc. (TSXV: ZLTO) (the “Company” or “BULGOLD”) is pleased to announce that it has received all outstanding assay data relating to the Lutila Gold Project (the “Property”). This information has now been validated and incorporated into the Company’s database. The Lutila exploration licence covers an area of 32.2km 2 and is prospective for quartz-adularia epithermal gold mineralisation.
1. Highlights
Drill hole CVDD001, drilled within the North East Block, intersected multiple low-grade gold intervals within rhyolite flow dome rocks; best interval of 18m @ 0.14g/t Au, 1,071g/t As & 167g/t Sb (from 33m).
Drill holes RRDD001 and RRDD002, drilled from the same drill pad within the Sinter Field failed to intersect any significant gold intervals; there were some indications of hydrothermal activity i.e. silicified pyroclastic rocks with disseminated pyrite.
Persistent prospecting activity led to the discovery of epithermal quartz vein material on the highest peak within the Sinter Field; located 2.7km north along Rhyolite Ridge from RRDD001 and RRDD002 and 1.7km south west from CVDD001. This is the first time that epithermal quartz veins have been recognised within the Sinter Field and validate the Company’s exploration model.
Additionally, 500m north east and along strike from the epithermal quartz veins the Company discovered an area of ancient mining located at the end of the ridgeline. A slot has been mined into the ridge face which measures 70m in width and 40m in height with the corresponding waste dump measuring approximately 200m in length and up to 50m wide. The waste dump is defined by an historic antimony soil anomaly. Rocks within the ancient mining area are predominantly strongly silicified ± chalcedonic veins, flow banded rhyolite and likely represent exposure of the upflow zone that the Company has been exploring for within the Lutila Gold Project.
Mapping and assessment of all sinters within the Sinter Field revealed that sinters located on Rhyolite Ridge (at the highest elevations) reflect the highest temperatures of formation and therefore proximity to the “hot springs” or “outflow zones” which continues to support the view that the 5km-long Rhyolite Ridge is one of the primary exploration targets on the Property.
The Company commenced its maiden drilling programme on the Property less than a year after incorporating a local subsidiary (Stredné Slovensko s.r.o.), demonstrating that the Company’s policy of proactive engagement with stakeholders results in a greater understanding of the modern gold exploration process.
The Property is located 5km south, along strike and within the same volcanic depression that hosts the historic quartz-adularia Kremnica gold mine (current JORC (2012) mineral resource estimate of 2.7Moz Au 2 ). Historic gold production is estimated by Finka (1995) to be 1.48Moz 1 .
Exploration target: underground, high-grade gold (Au) ± silver (Ag) quartz veins.
2 This is not a mineral reserve or mineral resource that has been prepared in compliance with the requirements of National Instrument 43-101. Source: Metals Tech Limited, ASX Release, 8th May 2023 ( https://wcsecure.weblink.com.au/pdf/MTC/02663482.pdf)
Quote from the President & CEO, Mr Sean Hasson:
“The discovery of strongly antimony anomalous epithermal quartz veins together with the nearby area of ancient mining represent a pivotal moment in the exploration of the Lutila Gold Project.
The Company has drill tested Rhyolite Ridge 2.7km south of this location and used the occurrence and distribution of outcropping sinters to guide such drilling efforts. It is now clear to the Company that future exploration drilling should take place within this +1,000m portion of Rhyolite Ridge where epithermal quartz veins are found at surface together with ancient mining activity which provide direct evidence for the presence of epithermal veins at depth beneath the ridgeline within the upflow zone.
The Lutila Gold Project is located favourably between two of the largest Au-Ag epithermal systems within the Central Slovakia Volcanic Field, the Kremnica gold deposit and the Banska Štiavnica gold-silver ore field, which, collectively, have produced significant amounts of precious metals over many centuries.
At BULGOLD we believe that the art of discovery is defined by subtlety, and one does not need to be reminded that the Fruta del Norte gold mine was discovered by drilling beneath a surface antimony anomaly to reveal the 300m long high-grade core of the deposit. With that in mind, the Company is evaluating a number of options to progress the discovery process on the Lutila Gold Project.”
2. Exploration Drilling
Three diamond drill holes were completed by the Company as part of its 2024 exploration programme. CVDD001 was drilled within the North East Block to test the Čertov vrch target area and RRDD001 and RRDD002 were subsequently drilled from the same drill pad within the Sinter Field on the western side of Rhyolite Ridge. A total of 1,615.8m was drilled, sampled and assayed; individual drill hole details are outlined below:
| Hole No. | Grid Name | X | Y | Z | Dip | Azimuth | Depth | | CVDD001 | UTM35N | 344666 | 5392610 | 594 | -67.4 | 091 | 515.4 | | RRDD001 | UTM35N | 342611 | 5388686 | 519 | -66.7 | 091 | 600 | | RRDD002 | UTM35N | 342618 | 5388688 | 519 | -50.3 | 126 | 500.4 |
Table 1. Exploration drill hole information.
CVDD001
Gold anomalous intervals from CVDD001, targeting beneath the Čertov vrch prospect area are outlined below:
18m @ 0.14g/t Au, 1,071g/t As, 167g/t Sb (from 33m) *
5m @ 0.13g/t Au, 988g/t As, 96g/t Sb (from 126m) *
6m @ 0.13g/t Au, 300g/t As, 30g/t Sb (from 358m) *
*2m minimum composite length, 2m maximum internal dilution, 0.1g/t Au cut-off; the Company considers this to represent a ‘geological cut-off’ which shows that gold is present in rhyolite volcanic rocks at anomalous values.
Geologically, CVDD001 intersected the following volcanic units:
0 – 23m: Feldspar-phyric rhyolite tuff.
23 – 51m: Rhyolite pyroclastic breccia.
51 – 340m: Flow banded rhyolite with steep, wispy, veinlets of chalcedony (± quartz) + pyrite approximately one per metre from 51 – 305m, after which the veinlets become carbonate + pyrite dominant from 305 – 340m.
340 – 481m: Flow banded feldspar-phyric rhyodacite with steep carbonate + pyrite veinlets dominating on a regular basis; pyrite also replaces hornblende phenocrysts and feldspar phenocrysts are variously altered to yellow/green smectite clays; strong to intense propylitic alteration.
481 – 488m: Rhyolite volcanic breccia, matrix supported with non-flow banded clasts of rhyodacite to dacite; feldspar phenocrysts are altered to green smectite clays and hornblendes have been replaced by pyrite and locally converted to iron oxides with disseminated pyrite within a red fine-grained matrix.
488 – 515.4m: Dacite with >70% feldspar phenocrysts altered to green smectite clays with accessory hornblende ± biotite commonly altered to iron oxides, quartz phenocrysts, when present, generally show corroded rims. Steep carbonate + pyrite veinlets, together with disseminated pyrite in the matrix increase from 502m.
Operationally, core recovery was good and averaged 99%. Drilling rates were reasonable; however, mechanical issues with the drill rig resulted in significant drilling downtime which led to the Company deciding to halt the drill hole at 515.4m rather than continuing drilling and risk losing the HQ drill string. The drill hole could be re-entered at a future date.
Figure 1. Examples of gold mineralised drill core from CVDD001; (A): hydrothermal breccia containing disseminated marcasite and clasts of quartz vein (upper left), chalcedonic quartz fragments and rhyolite volcanic rock (35.6m); (B): chalcedonic quartz vein with lattice bladed quartz textures (circled in red) within rhyolite rock (36.2m); (C): brecciated rhyolite rock with chalcedonic quartz matrix infill with minor disseminated and blebby marcasite (38.1m); (D): hydrothermal breccia containing chalcedonic quartz fragments with disseminated marcasite in rhyolite volcanic rock (51m).
Figure 2. Schematic geological cross section showing drill hole CVDD001 in relation to the gold mineralised quartz veins believed to be deposited within an upflow zone beneath the ridgeline that the Company was targeting.
RRDD001 & RRDD002
The drill site was selected to test the middle of the 4km long, north-south trending portion of Rhyolite Ridge that is surrounded by sinters, which represent the surface expression of upflow zones. The Company believed that this location was representative in terms of testing the potential of Rhyolite Ridge for mineralised epithermal veins at depth beneath the ridgeline, where we believed they may have been deposited within an upflow zone.
Geologically, RRDD001 intersected the following volcanic units:
0 – 3m: Sinter.
3 – 23m: Epiclastic rocks, coarse volcanic sandstones, fine grained tuff and lithic tuffs with weak bedding and grading together with devitrification textures after volcanic glass.
23 – 45m: Block and ash pyroclastic flow.
45 – 64m: Epiclastic rocks, polymictic volcanic sandstone to conglomerate composed of rhyolite material.
64 – 170.8m: Block and ash pyroclastic flow.
170.8 – 289m: Epiclastic rocks, volcaniclastic conglomerate and sandstone with intercalated tuff bands with spherulitic textures.
289 – 411m: Block and ash pyroclastic flow, matrix supported with clasts of flow and non-flow banded rhyolite; from 370m the ash/glass matrix is altered to yellow/green zeolite and/or smectite clays.
411.5 – 462m: Epiclastic rocks, volcaniclastic conglomerate and coarse sandstone with tuff bands.
462 – 481m: Block and ash pyroclastic flow with minor green zeolite and/or smectite clays.
481 – 485.3m: Silicified block and ash pyroclastic flow with disseminated and blebby marcasite in the matrix.
485.3 – 600m: Lacustrine sedimentary rocks, grey marls, black mudstones, grey, partly calcareous sandstones, green siltstones and lesser coarse sandstone composed of rounded quartz, limestone (marble?) and minor volcanic derived clasts.
Following the completion of RRDD001, the geological model was revised to incorporate the presence of lacustrine sedimentary rocks within the stratigraphy which would likely act as an aquitard within the upflow zone and to reflect the greater thickness of the volcanic pile (rhyolite pyroclastic/epiclastic products). The Company was encouraged by the silicification with associated marcasite of the pyroclastic flow immediately above the contact with the lacustrine sedimentary rocks and also the smectite alteration of the matrix within the pyroclastic flows. As such, it was decided to collar RRDD002 at a shallower angle from the same drill pad so as to cross the ridgeline and confirm (or not) the presence of an upflow zone beneath this portion of Rhyolite Ridge.
8i9
Figure 3. Schematic representation of the Company’s revised geological model for Rhyolite Ridge following the completion of RRDD001.
Geologically, RRDD002 intersected the following volcanic units:
0 – 5.3m: Sinter.
5.3 – 24.5m: Epiclastic rocks, tuff, coarse volcanic sandstone composed of rhyolite rock.
24.5 – 57m: Block and ash pyroclastic flow.
57 – 81.6m: Epiclastic rocks, coarse, polymictic, volcanic sandstone and conglomerate.
81.6 – 206.2m: Block and ash pyroclastic flow.
206.2 – 428.1m: Epiclastic rocks, coarse volcanic sandstone/conglomerate/breccia composed of lithic rhyolite clasts with tuff layers.
428.1 – 500.4m: Block and ash pyroclastic flow.
RRDD002 failed to show evidence of an upflow zone below this portion of Rhyolite Ridge.
3. Epithermal Quartz Veins within the Sinter Field
Persistent prospecting following the completion of exploration drilling led to the discovery of epithermal quartz veins on and just below the equal highest peak (687mRL) within the Sinter Field. The quartz vein material is located 60m vertically above and 1km north east from the nearest outcropping sinter. Sinters form at the paleo-water table, while epithermal quartz veins form beneath the paleo-water table.
Figure 4. Field images of the epithermal quartz vein pieces located at the equal highest peak within the Sinter Field.
The epithermal quartz vein fragments represent the high-level expression of an upflow zone located beneath this +1,000m portion of Rhyolite Ridge, where the overall strike of the ridge abruptly changes from a north-south to a north-east orientation. The vein pieces are dominated by low temperature, low fluid-flux textures and are commonly coarsely banded chalcedonic quartz with zones of quartz lattice bladed textures which indicate that boiling has occurred. Minor included fragments of rhyolite rock within the vein pieces clearly indicates that the veins formed within rhyolite rock. They are strongly anomalous for antimony (average of 228g/t Sb) with very low levels of Au, Ag and As and correlate well with the historic Sb soil geochemistry.
Additionally, 500m north east and along strike from the epithermal quartz veins the Company discovered an area of ancient mining located at the end of the ridgeline. A slot has been mined into the ridge face which measures 70m in width and 40m in height with the corresponding waste dump measuring approximately 200m in length and up to 50m wide. The waste dump is defined by a historic antimony soil anomaly. Rocks within the ancient mining area are predominantly strongly silicified ± chalcedonic veins, flow banded rhyolite and likely represent exposure of the upflow zone that the Company has been exploring for within the Lutila Gold Project (Figure 6).
Historic gold exploration within the Lutila Gold Project has been ongoing for centuries given its location immediately south and along strike from the Kremnica gold deposit, which has been mined for approximately 1,000 years, and in that time, this is the first recorded occurrence of epithermal quartz veins within the Sinter Field. The Company has drill tested Rhyolite Ridge 2.7km south of this location and used the occurrence and distribution of outcropping sinters to guide such drilling efforts. It is now clear to the Company that future exploration drilling should take place within this +1,000m portion of Rhyolite Ridge where epithermal quartz veins are found at surface together with ancient mining activity which provide direct evidence for the presence of epithermal veins at depth beneath the ridgeline where they may have been deposited within an upflow zone (Figure 13, Figure 14 & Figure 17).
Figure 5. Slabbed examples of epithermal quartz veins from the north east trending, +1,000m long portion of Rhyolite Ridge. (A) Coarse chalcedonic banding with minor quartz lattice bladed bands; (B) quartz lattice bladed textures after carbonate indicating that boiling has taken place; (C) Coarse chalcedonic banding with minor quartz lattice bladed bands; (D) Coarse chalcedonic banding with minor quartz lattice bladed bands circled in red (centre left) together with an included fragment of rhyolite circled in red (centre); (E) & (F) Typical low temperature textures reflecting a low fluid-flux environment of formation within upper levels of the upflow zone.
Figure 6. Location of the area of ancient mining in relation to the area of epithermal quartz veins (purple circles). Green squares are locations of chalcedonic veinlets in rhyolite flow dome complexes, green outlines are bentonite open pits, solid black circles are the nearest outcropping sinters overlain on historic Sb soil geochemistry; 2m contours derived from LIDAR.
4. Chalcedonic Veinlets in Rhyolite Flow Dome Complexes
Prospecting by the BULGOLD exploration team also revealed the presence of chalcedonic veins/veinlets within rhyolite flow dome complexes located at higher elevations, principally on Rhyolite Ridge, but also found throughout the property. Only within the area of epithermal quartz veins are the two types of veins found together. They are moderately anomalous for antimony (average of 85g/t Sb) with very low levels of Au, Ag and As and correlate well with the historic Sb soil geochemistry. Their significance is poorly understood at this stage (Figure 16).
Figure 7. Examples of chalcedonic veins within rhyolite rock located throughout the property. (A) Float sample in field; (B), (C) & (D) Crudely banded chalcedonic veins in rhyolite rock; (E) & (F) Brecciated rhyolite rock with chalcedony matrix infill.
5. Alteration & Mineralisation within the North East Block
At surface, the North East Block is dominated by rhyolite ‘shingle’ float due to the abundance of flow banding within the rhyolite rocks in this area, however, below the 600mRL and more commonly around the 500mRL, altered and mineralised rhyolite rocks can be found as float in many areas. Figure 8 shows some examples of the float rock which represents a composite ‘stratigraphy’ from across the North East Block from low temperature alteration to low temperature gold mineralisation; these rocks are responsible for the extensive arsenic and antinomy anomalism as defined by historic soil sampling.
Figure 8. (A) Brecciated rhyolite with chalcedony matrix infill often found at higher elevations (0.12% As, 179g/t Sb); (B) Silicified epiclastic volcanic breccia dominated by various rhyolite clasts (81.3g/t As, 35.6g/t Sb); (C) Silicified rhyolite rock with disseminated pyrite (381g/t As, 73.4g/t Sb); (D) Weakly developed chalcedonic quartz vein in rhyolite rock with pseudo moss textures and a radiating fabric (37.7g/t As, 961g/t Sb); (E) Coarsely banded chalcedonic quartz vein with quartz lattice bladed textures circled in red (0.81g/t Au, 5g/t Ag, 74.8g/t As, 26.6g/t Sb); (F) Chalcedonic quartz vein with coarse banding and minor quartz lattice bladed textures (0.58g/t Au, 5.9g/t Ag, 38.5g/t As, 44g/t Sb).
6. Sinters
All sinters within the Sinter Field were mapped at 1:10,000 scale. The key finding from this exercise was that there is no preferred topographic level for the formation of sinters and they occur/outcrop at all topographic levels and are commonly ‘stacked’ in that they form significant sinter terraces, separated by tuff layers, across the property. The sinters show a strong correlation with antimony in the historic soil geochemistry (Table 2).
Figure 9. Stacked sinters within the southern pit wall of the Jelsovy potok bentonite open pit separated by tuff layers. The yellow dashed line outlines the base of each sinter horizon.
Additionally, 69 samples were collected from the sinter outcrops ± minor float across the western side of Rhyolite Ridge. These samples were then slabbed in the Lutila core shed and a detailed hand specimen review was completed based on textural characteristics using the Atlas of Siliceous Hot Spring Deposits (Sinter) and Other Silicified Surface Manifestations in Epithermal Environments (Hamilton et al, 2019) as a guide to determine the likely temperatures of sinter formation (Figure 15).
This study revealed that sinters located on Rhyolite Ridge (at the highest elevations) reflect the highest temperatures of formation and therefore proximity to the “hot springs” or “outflow zones”, which continues to support the view that the 5km-long Rhyolite Ridge is one of the primary exploration targets on the Property. Additionally, a review of historic bentonite exploration drilling revealed many sinters which do not outcrop and occur subsurface (Figure 16).
7. Discussion
The Lutila Gold Project is located favourably between two of the largest Au-Ag epithermal systems within the Central Slovakia Volcanic Field, the Kremnica gold deposit and the Banska Štiavnica gold-silver ore field, which collectively, have produced significant amounts of precious metals over many centuries. According to Kodera (2005) the Banska Štiavnica ore field has produced 2.6Moz Au and 129Moz Ag from the early middle ages until the twentieth century. The fact that low to intermediate sulfidation Au-Ag epithermal veins are intimately associated with rhyolite volcanism during the period 12.4 – 11.2Ma underpins the Company’s exploration model.