This report summarises geophysical studies conducted by Western Areas between October 2021 and October 2022, under the ADI Agreement ADI: RD02/296-GP Magneto Telluric (MT), Passive Seismic and Magnetic Modelling Study. The discovery of magmatic Ni-Cu sulphide at Sahara in 2020, represented a major milestone in Western Areas Exploration strategy and confirmed the presence of significant, intrusive-hosted magmatic Ni-Cu sulphide in the Fowler Domain. The aim of the project was to develop a 3D model of the Fowler Domain crust from the near surface to the Moho to identify the regional structural controls on the emplacement of Ni-Cu-PGE prospective mafic-ultramafic intrusions. Western Areas completed the following during the reporting period. • Magneto-telluric (MT) Survey – 3 lines for ~140 km and 82 stations - The MT survey uses a frequency of 10,000 Hz to 0.001 Hz, 'skin depth' at the highest frequency will approximately be 10m, and the maximum depth would be to the Moho. • Passive Seismic Survey – 3 lines for ~140 km and 82 stations – undertaken simultaneously as the MT survey to constrain the cover. This was a collaborative research project with the University of Adelaide Prof. Graham Heinson. • Magnetic Remanence Study – a joint study with CSIRO Clive Floss to investigate the influence of magnetic remanence in magnetic field survey data and to undertake magnetic petrophysics measurements on drill-core, in order to investigate links between that magnetisation and mineralization. A magneto-telluric survey was conducted by the University of Adelaide from the 3rd to the 17th of April 2022 along three transects across the Fowler Domain. In total, 82 stations were recorded with four components (Bx, By, Ex, Ey) recorded at 1000 Hz for two days or more at each station, using the GSSA-AuScope LEMI-423 BBMT instruments. A passive seismic survey was conducted at the same time as the MT survey using the same site locations. The passive seismic instruments were the AuScope IGU-16HR 3 component (X, Y, Z) 5 Hz instruments. The sample rate was set for 4 milli seconds, with the gain for each channel set at 24 dB. The magnetic remanence survey saw 76 samples from 13 diamond drillholes, collected at 7 prospects across the Western Gawler project and were sent to Clive Floss (CSIRO) for petrophysics measurements. All petrophysics measurements were made on 2.5 cm diameter, 2.5 cm height cylinders extracted along the axis of oriented drill-core. For all core samples, the volume, specific density, magnetic susceptibility, and natural remanent magnetisation (NRM) were measured. For selected core samples, anisotropy of magnetic susceptibility (AMS) and stability of remanent magnetisation (liquid nitrogen cleaning, alternating field, and thermal demagnetisation) were also measured. The quality of the data from the MT surveys was reported as good across all transects and all bandwidth, cover sequences are represented by the highly conductive zones overlying a highly resistive crust. Significant changes in depth of cover and possibly basement weathering have correlation to mapped faults. In the basement, there is reasonable correlation between shear zones and regions of slightly lower resistivity, however the dip and vertical extent is not known and are plotted as vertical. The MT data collected by the University of Adelaide was integrated with the local AusLAMP (Australian Lithospheric Architecture Magnetotelluric Project) data and other long-period legacy MT data sets to generate 3D inversion models of the Western Gawler Craton. A total of 128 sites of long-period MT (10-10,000 s) were inverted, covering an area ~ 600 km east-west from the SA-WA border, and 600 km north-south from the SA-NT border to the south to Streaky Bay in the Eyre Peninsula. Site spacing is approximately 50 km. The three transects of MT carried out in this ADI project however were not used in the 3D inversion due to the difficulty of resolving the inversion at vastly differing scales of investigation. The preferred model showed the top 5 km electrically conductive sedimentary Officer, Eyre and Eucla Basins, and the much more resistive Archaean and Mesoproterozoic Gawler Craton and Musgrave Province. The two most northern transects span strong resistivity gradients in the upper most mantle (40-60 km), indicating a boundary between the resistive Archean core of the Gawler Craton, with the more conductive Proterozoic Fowler Domain to the west. The 3D model highlights the presence of a more conductive body, possibly an anomalous structure lying directly below the northern ADI MT transects. The magneto-telluric survey was completed in conjunction with a passive seismic survey to provide constraint on the cover sequences. However, the data collected is inconclusive for this type of work and it is recommended that further data analysis is completed. Petrophysics measurements were made on the oriented core samples, significant variations in density, magnetic susceptibility and remanent magnetisation between samples of different lithology are consistent with local variations in the measured gravity and magnetic fields but unfortunately the boreholes do not directly test centres of magnetisation estimated from inversion of the most substantial magnetic field variations, limiting the opportunity to link those magnetic field variations with the petrophysics measurements. The magnetic remanence study also highlighted the complex nature of the high magnetic responses within the surveyed areas. Most prospects showing high magnetic TMI inversion model are in fact composed of multiple strong magnetic responses with a variety of directions and characteristics and overlapping each other. Many samples have also shown the characteristics of stable remanent magnetisation, but the directions are not consistent and the cause of it is unknown. The magnetic remanence study highlighted the complex nature of the magnetisation in the Western Gawler project most likely due to numerous deformation and metamorphic events. This means that magnetic studies aren’t effective to define all of the mafic and ultramafic intrusions within the project areas.