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ASX Announcement | ABN 91 124 752 745 |
2 February 2022
only | Significant Resource Upgrade at Twin Hills Project |
HIGHLIGHTS | |
use | Updated JORC 2012 Mineral Resource estimate for The Twin Hills deposits (Lone Sister and 309) of 12.9 |
million tonnes at 1.8 g/t Au for 760,700 ounces (previously 633,000 ounces) of contained gold on | |
granted mining leases (see Table 1). | |
Combined gold resources under GBM's ownership in the Drummond Basin now total approximately | |
1.6 Moz across the Yandan, Mt Coolon and Twin Hills assets (see Figure 1). All are located within 70 km of | |
GBM's proposed "Drummond Basin Processing Hub" centred on the Yandan ML's, which has significant | |
infrastructure (i.e. water storage dams, tailings facilities, airstrip, leach pads and grid power). | |
Drummond Basin, QLD Total - 41 million tonnes at 1.2 g/t Au for 1,612,200 ounces | |
personal | Twin Hills is considered highly prospective for the discovery of additional mineralisation, with |
deposit to evaluate opportunities to deepen the pit below the 1050 RL used in this resource update. | |
preliminary analysis suggesting high grade gold shoots at 309 and Lone Sister may be open at depth. GBM | |
is now aiming to commence drilling in the coming weeks at Twin Hills to test these targets. | |
GBM's analysis of the deposit geometry and grade distribution suggests that the 309 and Lone Sister | |
resources maybe be successfully mined via a combination of bulk minable open pit and bulk | |
underground mining methods. | |
Resource upgrade work will continue with new pit optimisation work commencing soon on the 309 | |
GBM Managing Director and CEO, Peter Rohner, commented:
"GBM's geological and mining team is rapidly gaining further knowledge of the Twin Hills deposits to improve the resource model and evaluate mining scenarios which will assist in focusing drilling activities which will commence shortly. The planned drilling programs will focus on increasing the confidence of the resource, improving resource knowledge in the shallower likely open pit resources and extending the resources at depth. This transformational acquisition represents a significant step in the execution of our 'processing halo' strategy
Forto build over two million ounces under ownership within the Drummond Basin, providing an entry into the development of a genuine mid-tier Australian gold company."
Twin Hills Resource Summary
The 309 and Lone Sister deposits are low sulphidation, epithermal gold deposits hosted within the western arm of the Drummond Basin in Queensland. The Drummond Basin is host to a number of significant gold deposits and is considered by GBM to hold potential for further discoveries.
The 309 and Lone Sister gold deposits are located 7 kilometres apart and linked by a major north-south structural lineament. Both deposits have previously been interpreted as intrusion related, high gold fineness, low sulphidation epithermal gold deposits, sometimes exhibiting bonanza gold grades (as evidenced by the peak gold value in the 309 deposit of 2,940 g/t Au, with 300 individual metre samples exceeding 30 g/t Au, and a peak gold value of 939 g/t Au at Lone Sister). Refer ASX: GBZ release 18 January 2019.
GBM considers that potential depth extensions and strike repetition of both the 309 and Lone Sister deposits have not been adequately tested.
No changes were made to the 2019 resource model, however metallurgical and mining costs were reviewed and as a result of the increase in the gold price the cut-off grade was reduced from 1.0 g/t Au to 0.4 g/t Au for the open pit resources.
onlyThe 309 Deposit has been re-estimated to comprise 10.8 Mt averaging 1.4 g/t Au containing 500,600 ounces of gold
and 783,100 ounces of silver (assuming open pit mining to 1050 RL, or a depth of approximately 200 m, and underground mining below 1050 RL).
The Lone Sister Deposit is re-estimated at 2.0 Mt at an average grade of 4.0 g/t Au containing 260,100 ounces of gold and 604,800 ounces of silver (refer Table 1).
Table 1: Twin Hills Resource Summary for the 309 and Lone Sister Gold Deposits (rounded for reporting '000
tonnes, '00 ounces, 0.0 grade). See previous release ASX GBM 18 January 2019 'Mount Coolon and Twin Hills Combined useR source Base Approaches 1 Million Ounces' also.
Open Pit Resources (above 1050 RL) stated at 0.4 g/t Au cut-off and Underground Resources (below 1,050 RL) stated at 2.0 g/t Au cut-off.
Category | Cut-off | Tonnage | Grade | Contained Metal | |||||||||
Au (g/t) | (t) | Au (g/t) | Ag (g/t) | Au (oz) | Ag (oz) | ||||||||
personal | 309 Deposit | ||||||||||||
Open Pit (above 1050RL) | |||||||||||||
Measured | 0.4 | 586.000 | 2.7 | 4.8 | 50,300 | 85,500 | |||||||
Indicated | 0.4 | 5,470,000 | 1.4 | 2.6 | 253,200 | 457,500 | |||||||
Inferred | 0.4 | 4,165,000 | 0.9 | 1.5 | 120,200 | 199,400 | |||||||
Total open pit | 0.4 | 10,220,000 | 1.3 | 2.3 | 423,500 | 742,400 | |||||||
Underground (below 1050 RL) | |||||||||||||
Measured | 2.0 | ||||||||||||
Indicated | 2.0 | 110,000 | 4.8 | 3.4 | 16,800 | 11,900 | |||||||
Inferred | 2.0 | 510,000 | 3.7 | 1.8 | 60,100 | 28,800 | |||||||
Total underground | 2.0 | 620,000 | 3.9 | 2.0 | 76,900 | 40,700 | |||||||
Total 309 Deposit | |||||||||||||
Measured | 0.4 / 2.0 | 586,000 | 2.7 | 4.8 | 50,300 | 85,500 | |||||||
Indicated | 0.4 / 2.0 | 5,580,000 | 1.5 | 2.6 | 270,000 | 469,400 | |||||||
Inferred | 0.4 / 2.0 | 4,675,000 | 1.2 | 1.5 | 180,300 | 228,200 | |||||||
For | TOTAL | 0.4 / 2.0 | 10,841,000 | 1.4 | 2.2 | 500,600 | 763,100 | ||||||
Lone Sister Deposit | |||||||||||||
Measured | 2.0 | ||||||||||||
Indicated | 2.0 | ||||||||||||
Inferred | 2.0 | 2,010,000 | 4.0 | 9.4 | 260,100 | 604,800 | |||||||
Total | 2.0 | 2,010,000 | 4.0 | 9.4 | 260,100 | 604,800 | |||||||
Total Twin Hills | |||||||||||||
Measured | 0.4 / 2.0 | 586,000 | 2.7 | 4.5 | 50,300 | 85,500 | |||||||
Indicated | 0.4 / 2.0 | 5,580,000 | 1.5 | 2.6 | 270,000 | 469,400 | |||||||
Inferred | 0.4 / 2.0 | 6,685,000 | 2.0 | 3.9 | 440,400 | 833,000 | |||||||
TOTAL | 0.4 / 2.0 | 12,851,000 | 1.8 | 3.4 | 760,700 | 1,387,900 | |||||||
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Drummond Basin Consolidation and Processing Halo Strategy - now at ~1.6 Moz
Figure 1: Drummond Basin Processing Halo and Resource Consolidation Summary
only | |||||||||||||||||
Mt Coolon Project | |||||||||||||||||
use | 100% GBM | ||||||||||||||||
Resource: 330 koz Au1,2 | |||||||||||||||||
Conway | |||||||||||||||||
Legend | |||||||||||||||||
Clewitts | Bimurra | GBM EPM granted | |||||||||||||||
Yandan Project | GBM EPM application | ||||||||||||||||
100% GBM | (submitted) | ||||||||||||||||
Resource: 521 koz Au6 | North East | ||||||||||||||||
personal | |||||||||||||||||
Ridge | Project Size | ||||||||||||||||
Yandan | Eugenia | ||||||||||||||||
Large | |||||||||||||||||
1.75 to 4.1 Moz | |||||||||||||||||
Illamahta | Glen Eva | Medium | |||||||||||||||
Eastern | 0.15 to 1.75 Moz | ||||||||||||||||
Koala | Siliceous | Small | |||||||||||||||
Verbena | <0.15 Moz | ||||||||||||||||
Epithermal | |||||||||||||||||
Sinter | prospect | ||||||||||||||||
Regional Geology | |||||||||||||||||
Other Post Mineral | |||||||||||||||||
Cover | |||||||||||||||||
Quaternary to Mid. | |||||||||||||||||
Carboniferous Cover | |||||||||||||||||
Late Devonian - Early | |||||||||||||||||
309 | Carboniferous | ||||||||||||||||
Sediments | |||||||||||||||||
Twin Hills Gold Project | Lone Sister | Late Devonian - Early | |||||||||||||||
100% GBM | Carboniferous | ||||||||||||||||
309 + Lone Sister | Volcano-Sedimentary | ||||||||||||||||
Resource: 761 koz Au1 | |||||||||||||||||
Pre-Mineral | |||||||||||||||||
20 km | Basement | ||||||||||||||||
1. GBM ASX Announcement, 18 January. 2019, Mt Coolon and Twin Hills Combined Resource Base Approaches 1 Million Ounces and 2 February 2022 | |||||||||||||||||
2. GBM ASX Announcement, 4 Dec. 2017, Mt Coolon Gold Project Scoping Study *Including Tailings | |||||||||||||||||
For3. Evolution Mining. Pajingo-Fact-Sheet_March-2016_web-1.pdf | |||||||||||||||||
4. Osborne & Chambers. (2017). Pajingo Gold deposit. In Philips (ed), Australian Ore Deposits. AusIMM. Monograph 23. | |||||||||||||||||
5. Drummond Gold Limited , 24 Oct 2014, Mining 2014 Presentation, October Brisbane | |||||||||||||||||
6. GBM ASX Announcement, 23 Dec 2020, Mt Coolon and Yandan Combined Resources Total 852,000 oz following completion of Yandan acquisition | |||||||||||||||||
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Twin Hills Geology and Exploration Potential - High Grade Shoots Open to Depth
Twin Hills is hosted by a sedimentary-volcanic package interpreted to have been deposited in a late Devonian age, structurally controlled, pull apart basin that formed along the margin of a Cambro-Ordovician age metamorphic basement high, the Anakie metamorphic inlier (refer Figure 2).
onlyFigure 2: Geological setting of 309 and Lone Sister Deposits
For usepersonal
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Gold-silver mineralisation is temporally and probably genetically linked to subvolcanic to volcanic felsic domes and related breccia pipes. The age of mineralisation at Lone Sister and by association the related domes has been shown to be early Carboniferous (341 to 346 ma).
Mineralisation at the Twin Hills project, 309 and Lone Sister deposits (Figure 2) belongs to the felsic dome
related, high gold fineness, low sulphidation quartz sulphide class of mineralisation that has produced a number
onlyz ne that is hosted within a rhyolite feeder dyke to a flow dome and the adjacent wall rock sediments. Better g ld mineralisation in these deposits is strongly associated with epithermal quartz breccia matrix fill and cross
of notable high value gold deposits including the high-grade Sleeper deposit and large bulk minable style
deposits like Round Mountain in Nevada. This class of deposit usually develops an early phase of quartz-
su phide gold mineralisation followed by later stages of very high-grade often free gold quartz and or gold electrum chalcedony events, as is seen at Twin Hills, that are important to the deposit economics.
GBM's preliminary interpretation shows that the Twin Hills deposits are characterised by the 309
(phreatomagmatic to phreato-hydrothermal) milled matrix breccia body and the Lone Sister breccia and veinlet
cutting quartz fracture veinlet networks, forming discontinuous veinlet corridors that crosscut the host rock. GBM believes that the 309 and Lone Sister deposit characteristics are better suited to open pit or underground bulk mining approach compared to the selective underground mining previously used at Twin Hills.
For personal use | |
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Figure 3: Plan view of the Twin Hills 309 gold deposits. These show ore blocks in various grade ranges and previous underground development.
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GBM Resources Limited published this content on 02 February 2022 and is solely responsible for the information contained therein. Distributed by Public, unedited and unaltered, on 02 February 2022 01:18:00 UTC.