The Yarrie Lithium Project is located in the highly prospective Pilbara region of Western Australia. The Yarrie Lithium Project is considered highly prospective for hard-rock Lithium-Tin-Tantalum (Li + Sn + Ta) mineralisation in pegmatites. The area is also known for the economic lithium deposits of Wodgina (Mineral Resources / Abermale), Pilgangoora (Pilbara Minerals) and Marble Bar (Global Lithium Resources).
The figure below depicts a satellite location map of the Yarrie Lithium Project as well as surrounding projects:
The Yarrie Lithium Project is situated in the east Pilbara Granite-Greenstone Terrane. The predominant rock type in the tenement area is Archean Granite with varying amounts of late-stage pegmatite fractionates. In the Pilbara region, late-stage granites may be highly fractionated and act as the source for intrusion of rare metal pegmatites into the surrounding stratigraphy.
These pegmatites may include spodumene bearing systems, as well as tin and tantalum mineralisation. These are the targeted minerals as well as the potential for Gold.
Initial Reconnaissance Exploration
During the Quarter ended 31 March 2022, Askari Metals has completed reconnaissance over the Yarrie Lithium Project via a helicopter flight, on-ground inspections and sampling.
The purpose of the reconnaissance visit at the Yarrie Lithium Project was to investigate the type of Granitic exposures and to ascertain the age and mineralogy of both the granites and pegmatites. This will assist in determining the geochronology of the area, which will drive the next stage of exploration. The Company also identified important structural controls, which will be important in future phases of exploration.
Images of the reconnaissance program as shown below.
Project Wide Targeting
An investigation of the underlying geology combined with the results of the Hyperspectral Survey and the initial reconnaissance exploration program has enabled the Company to generate a targeted “lithium-exploration” geological model, designed to provide focus areas within this district-scale opportunity where dedicated lithium exploration can be conducted. The outcome of this, subject to results, will demonstrate anomalism over high-priority areas where further exploration can be undertaken, therefore generating key focus areas within the Yarrie Project.
Initial geological reconnaissance was undertaken by the Company with the assistance of lithium pegmatite specialist, Dr Mike Grigson of Arc Minerals, an expert in granitic geology. Following his field observations, Dr Grigson inferred that the outcrops of monzogranite in the area are part of the Sisters Supersuite of granitic rocks. In the southern part of the project, these rocks contain cross-cutting pegmatite dykes with biotite, which are of significant interest to the Company as it relates to lithium pegmatite exploration.
An investigation into the detailed geology and a geological-modelling concept review undertaken by the Company has identified additional areas of interest within the tenement package.
The recently completed Hyperspectral Survey at the Yarrie Project identified several high-priority exploration targets using a multivariate statistical classiﬁer to separate the LWIR signals over the 86 known lithium occurrences around Marble Bar from the rest of the scene. This task combines the LWIR responses most associated with the Li-Sn-Ta occurrences in the area. A single “target” map is then generated identifying areas that best represent the Lithium endmember signatures. These targets together with the additional targets generated from the geological modelling completed by the Company will be the focus of the ground-based field exploration program.
The targets generated through the Hyperspectral Survey are identified in Figure 5 below (refer to ASX announcement dated 17 February 2022).
The geological modelling information has been compiled with the information generated from the recently completed Hyperspectral Survey and initial reconnaissance field visit completed by the Company and a project wide target map has been generated as set out in Figure 5 below. This has refined the design and execution of the upcoming field exploration program at the Yarrie Lithium Project. The Hyperspectral Survey and the reconnaissance field visit identified several geological structures that are conducive to lithium mineralisation emplacement, and which warrant further exploration and follow up.
The Yarrie Lithium Project is a district-scale lithium exploration opportunity located in the eastern Pilbara lithium hotspot adjacent to and along strike of major and growing hard-rock lithium deposits. Due to its favourable location and underlying geology, the Yarrie project is considered highly prospective for hard-rock lithium mineralisation in pegmatites.
As the Yarrie project is located in an emerging province where lithium exploration is only relatively recent, the Yarrie project has not been subject to historical lithium focused exploration. Therefore, exploration at the Yarrie project requires a suitable approach to identify targets and progress the project along the value curve. As part of the general exploration process the Company follows, a targeting rationale was generated.
Lithium mineralisation and more precisely spodumene is the target mineral at the Yarrie project. Spodumene is a high-temperature pyroxene generally derived from dark (mafic) rocks, inferring that the geological environment must be hot enough and have a mafic component to supply the required minerals to produce spodumene.
Therefore, the Company’s exploration design basis and project wide targeting rationale has been developed based on identifying a suitable “Heat Engine” to drive spodumene formation with mafic geology nearby to serve as the source geochemistry for LCT pegmatite formation.
The mineralisation model designed by the Company concludes that the mafic geology can either be sedimentary or igneous, and the heat source can either be the granite itself or heat generated by metamorphism. The geological age of the rocks in any given area is taken into account when we develop our targets as well as mineral assemblages such as muscovite, feldspar megacrysts and tourmaline. Mineral mobility is also taken into consideration when we determine the sampling methodology for a given area to consider the likelihood of a mineral surviving the weathering process.
The Company used Aster based hyperspectral analysis to identify initial targets on the Yarrie Lithium Project (see ASX announcement date 17 February 2022). These targets were visited during an initial reconnaissance visit (see ASX announcement dated 1 March 2022). The exploration rationale described above considered the targets identified by the Hyperspectral Survey as well as the initial reconnaissance field visit and generated additional “focused” targets in the same general areas.
Several sub-parallel dolerite (mafic) dykes, belonging to the Black Range Dolerite Suite (~2772Ma) as well as other mapped ultramafic units in the central and eastern parts of the Yarrie project have been identified as targets. The contact boundaries of granitic units have also been included as targets as well as areas believed to include pegmatite dykes identified from aerial photography.
During the upcoming planned field program, the Company will use various methods for collecting sample and anomalism data whilst in the field, including stream sediment sampling, rock chip sampling and mapping. Stream sediments are very useful to determine the prospectivity of a large area, while rock chip sampling is more confined to the local area surrounding the sample. Both sampling methods will be analysed with multi-element assays, scrutinising the results for various pathfinder element ratios. Field mapping and geological observations will identify the mineral assemblages of the various outcrops and add valuable information required to vector toward the spodumene target.
The primary target outlined in Figure 6 below is depicted with a green dashed line and measures 32km x 13km and targets an area underlain by cross-cutting geological structures proximal to the mafic dyke that has been mapped across the central part of the tenement.
The map below depicts the targets identified by the Askari Metals geological team.