b'FeatureImaging the supergene search space with ANTThe host stratigraphy to the Alford East prospect is the Oorlanoconsisted of 96 geodes that remained in the \x1eeld between nine Metasomatite which is comprised of alkali feldspar, iron-rich,and eleven days. The total area surveyed was approximately 3 km.carbonate and calc-silicate metasomatic rocks formed during the main IOCG mineralising event that a\x1fected large swathesEmpirically derived Greens functions are obtained from station of the eastern Gawler Craton (Cowley et al. 2003; Kontonikas- pair cross-correlation functions using the approach outlined by Charos et al. 2014). Supergene mineralisation is hosted withinBensen et al. (2007). From the processed data, a set of cross-variably weathered and sheared metasomatic rocks. Calcretecorrelations are computed for each of the unique station pairs. geochemistry across the region provided an indication ofThe resulting cross-correlation functions for each station pair buriedmineralisation in the area and was followed up byare then linearly stacked.drillingand identi\x1eed anomalous copper in the weatheredTo obtain a 3D model of the subsurface shear-wave velocities, basement (Wynne et al. 2019). Low grade copper mineralisationphase velocity dispersion measurements are extracted from the is widespread throughout the project area, with chalcocitecross-correlation functions using two independent methods: being the dominant copper mineral in the lower portion of the(1)the real part of the Fourier transform of the correlation supergene zones along with native copper and malachite in thefunctions is \x1etted with a \x1erst-order Bessel function of the \x1erst upper, oxide zones Wynne et al. 2019 (ThorEnergy PLC, 2023). kind (Aki, 1957; Ekstrm et al., 2009) and (2) the dispersion curves Some of the best historical diamond drilling interceptson an FTAN image are automatically picked for each correlation include 40.8 m @ 0.42% Cu and 0.07 ppm Au from 90 m infunction (Levshin et al. 1972; Luo et al. 2015). After the phase hole ALDDH017, and 20 m @ 0.27% Cu and 0.16 ppm Au fromvelocity measurements have been made, the approach of (Mordret 196m in hole ALDDH021 (Wynne et al. 2019). Based on theseet al. 2019) is used to regionalise the phase velocity dispersion results Thor generated an Inferred Mineral Resource estimatemeasurements for each frequency to create phase velocity maps. 125.6Mt @ 0.14% Cu containing 177 000 t of contained copperThis e\x1fectively creates a dispersion curve for each cell in the 2D and 71500 oz of contained gold (Table 1). Thor undertook agrid, which is then inverted for a 1D velocity model at each cell. targeted oxide diamond drilling programme in 2021, whichThe inversion results are constrained to a library of 50 000 forward returned high grade intercepts up to 72.7 m @ 1.0% Cu andmodels generated by uniform Monte-Carlo sampling of the 0.19g/t Au from 6.3 m, including 18.2 m @2.0% Cu andexpected model space and must \x1et the data within an RMS error 0.34g/tAu from 15.8 m in 21AED005 (Thor Energy 2021). bound of 5%. The resulting ensemble of 1D models is then gridded over a domain with XYZ dimensions to recover a full 3D velocity model. The approximate resolution of the ANT model is around ANT methods 10% of the depth, such that at 300 m depth, for example, the Ambient noise tomography utilises background seismic noisemodel is able to resolve features that are greater than 30 m wide.in the Earth as the signal for measuring subsurface velocity structure. An array of custom-built Fleet Space geophones (OlivierAlford East ANT surveyet al. 2022) were used to record the arrival of low-frequency surface waves created by natural and anthropogenic seismicThe recorded ambient seismic noise was detected sources. This technique relies on estimates of seismic Greenspredominantly from the south-west corner of the survey areas functions between station pairs, such that every receiver is turned(Figure 3). High quality surface wave noise was recorded into a virtual active source that provides information about thedown to 1.2 Hz. When considering the array aperture of each subsurface. The ANT survey in the Alford East project comprisedindividual array, this enabled consistent imaging down to 500 m two sub-surveys, an eastern and western deployment. Eachdepth with high resolution.Table 1.Alford East Mineral Resource Estimate as at 22January 2021.Domain TonnesCu % Au g/t ContainedContained (Mt) Cu (t) Au (oz)AE_1 24.6 0.12 0.021 30 000 16 000AE_2 6.8 0.13 0.004 9 000 1000AE_3 34.9 0.09 0.022 33 000 25 000AE_4 8.0 0.11 0.016 8000 4000AE_5 11.0 0.22 0.030 24 000 11 000AE-8 (NP) 31.3 0.19 0.008 61 000 8000AE-7 (LW_E) 7.7 0.14 0.025 10 000 6000AE-6 (LW_W) 1.3 0.13 0.011 2000 500Total 125.6 0.14 0.018 177 000 71 500Note: MRE reported on oxide material only, at a cut-o\x1c grade of 0.05% copper,Figure 3. Beamforming plot to locate dominant source direction and location whichisconsistent with the assumed in situ recovery technique. For details see from Alford East survey arrays. Ambient noise direction is predominantly south-https://thorenergyplc.com/projects/alford-copper-projects/west, in the direction of the township of Alford.APRIL 2024PREVIEW 41'