ASX ANNOUNCEMENT 22 October 2020
Exploration Update - Eidsvold drilling to commence and 8 Mile drilling completed
Five coincident, independent datasets compiled - all strongly support the existence of a very large Intrusion related gold system at the Great Eastern Target, Eidsvold Project
Maiden drilling program at the Great Eastern Target to commence
11 drill hole program at 8 Mile Project completed, assays awaited
Metal Bank Limited (ASX:MBK) ('Metal Bank', 'MBK' or the 'Company') is pleased to provide an update on the exploration programs at its 8 Mile and Eidsvold intrusion related gold projects in Southeast Queensland.
At the Eidsvold Project, additional IP geophysics and surface soil programs at the Great Eastern and Forty Horse Targets have been completed.
The Company has now compiled five independent datasets which all support the existence of a very large intrusion related gold system at the Great Eastern Target. The target is interpreted to lie 50 - 80m beneath overlying post mineral sediments (refer to Figure 1 and Figure 2). The datasets include:
new pathfinder soil geochemistry,
new pH soil geochemistry,
new pole-dipole IP geophysics,
all combined with
existing airborne magnetic and
airborne electro-magnetic (EM) geophysics modelling1.
All of the five datasets have now been combined into a robust intrusion related exploration model to refine the upcoming drill program design.
The maiden Great Eastern Target drill program is anticipated to commence within seven days and includes two fully funded drill holes to 250m depth each as part of the Queensland government (CEI) Collaborative Exploration Initiative.
At the 8 Mile Project, an 11 hole drill program has been completed targeting step out and infill drilling and step back drilling to directly test for a bulk tonnage intrusion related system. All results are awaited.
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P a g e | 1 Metal Bank Limited ABN 51 127 297 170 Suite 506 Level 5 50 Clarence Street Sydney NSW 2000
Commenting on the commencement of drilling at the Great Eastern Target, Metal Bank's Chair, Inés Scotland said:
"While we eagerly await the results of the 8 Mile drill program, we are very excited to commence the first ever drilling program at Eidsvold's Great Eastern Target. It is very rare to have five different exploration datasets all supporting the existence of a large intrusion related gold system and we look forward to the opportunity of being the first to explore this very large target with our upcoming drill program."
The Great Eastern Target is located within the Eidsvold intrusive complex, 6 km northeast of the 100K oz Au historical production Eidsvold goldfield. The target is completely overlain by post mineralisation sediments.
Exploration to date at the Great Eastern Target has focused on building robust technical support for the existence of a large intrusion related gold system prior to drilling. MBK has now completed five different studies, including using a variety of geophysical and surface geochemistry techniques, (refer to Figure 1 and Figure 2), which all support the existence of a very large-scale intrusion related gold system beneath the post mineral sediment at the Great Eastern Target.
Geophysical Support for the Great Eastern Target IRG system
The Great Eastern Target was initially identified based on a strong negatively polarized air magnetics bullseye anomaly with a peripheral magnetic ring, as shown in the middle image in Figure 1. The negatively polarized anomaly was 3D modelled and interpreted to most likely represent a deep remnant polarized core at approximately 800 m depth with striking similarities to the core of the 3M oz Au Mt Leyshon deposit. At the Mt Brady target, 6 km to the northwest and within a rare area of outcropping intrusive rocks, peripheral magnetic ring zones have been shown to be directly related to hornfelsing, which is the heating up of cooler host rocks adjacent to the emplacement of a hot intrusion. The extent of the intrusive target at the Great Eastern Target was therefore established on the basis of the hornfelsed ring, with a target size estimated at 3.5 x 2 km. A zone of washed out magnetism is evident between the inner core and hornfelsing. This zone is interpreted to reflect hydrothermal destruction of magnetite typical of phyllic alteration, which is the style of alteration commonly associated with Au mineralization surrounding the core of IRG systems.
Airborne Electro-Magnetics (EM)
Airborne EM was flown over the Eidsvold Project in 2018. A marked drop in resistivity was identified and 3D modelling showed this resistivity anomaly surrounding and well above the inner core identified from the airborne magnetics2. Refer to the upper image in Figure 1 for the outline of the 3D resistivity model. This drop in resistivity is typical of the phyllic alteration zone within IRG systems. Spatially, it matches nearly perfectly with the zone of magnetite destruction and is
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therefore interpreted to represent a second data set in support of a large alteration halo above and surrounding the inner core identified from the air magnetics. This area is interpreted as being the most prospective area for gold mineralization within the IRG system.
Figure 1: Great Eastern Target airborne magnetic, airborne EM and IP geophysics all showing strong support for a large IRG system
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Induced Polarization (IP)
MBK has completed one 2.5 km north-southpole-dipole induced polarisation (IP) geophysics line to better refine drill targets, which runs through the middle of the target area. The IP models highlight three very distinct anomalies within the Great Eastern Target, in the order of 500 m wide each. These IP anomalies are shown in the lower two images in Figure 1. The resistivity levels in the anomalies are those expected for silica-sericite (phyllic) alteration when taking into account the attenuative effects of post mineral sedimentary cover. The presence of elevated chargeability within the anomalies relative to background, directly reflects the presence of sulphides. Accordingly, the IP geophysics modelling strongly supports a sulphide rich phyllic alteration zone above and surrounding the core zone of an IRG system.
Geochemical Support for the Great Eastern Target IRG system
Ultra-Trace soil geochemistry
MBK has completed soil sampling over a 200 m x 200 m grid within the overlying sediments at the Great Eastern Target. The sample locations are shown in Figure 2. Samples were assayed using trace level detection to identify dispersion of metals within the sediment overlying the target area intrusion. After normalising the data against the effects of Fe scavenging, which can lead to false positive anomalies at these low detection levels, an exceptionally coherent metal zonation is recognised, which is typical of the metal assemblages of other large IRGS systems in Eastern Queensland.
The zoning comprises a well-defined central Mo-Pb-As-(Te-Bi) zone. This assemblage is indicative of the high temperature part of the system as shown in the upper image in Figure 2. This central high temperature zone is situated directly over the interpreted inner core zone defined in airborne magnetics and the central IP anomaly. An outer lower temperature Au-As-Cu-Zn-Sb zone surrounds the high temperature zone and is coincident with the phyllic outer zone identified in geophysics. This dataset therefore provides quantitative support for, and typical of, the geochemical zonation expected in an IRG system.
Acidity analysis of the same soil samples has also been completed, with results shown in the lower image in Figure 2. Any sulphides present from either alteration or mineralisation within the underlying intrusive, when subject to weathering at the contact with overlying sediment, will oxidise and therefore produce low levels of sulphuric acid. The acidity of ground water therefore increases and can be reflected at surface from groundwater dispersion. At the Great Eastern Target, a very coherent increase in acidity has been defined over an area which is coincident with the overall multi- element geochemistry zonation, IP chargeability anomalism, resistivity EM anomalism and airborne magnetics anomalism. This strongly supports the presence of sulphides within the underlying intrusive and the interpretation is that this increase in sulphides is directly related to alteration and/or mineralisation of an IRG system.
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Metal Bank Limited published this content on 22 October 2020 and is solely responsible for the information contained therein. Distributed by Public, unedited and unaltered, on 21 October 2020 23:44:00 UTC