b'Discovery of the Havieron Au-Cu deposit, WAFeatureDiscovery of the Havieron Gold-Copper deposit, WAJames E. HannesonAdelaide Mining Geophysics PL24 Justine St, Flagstaff Hill, SAjim.hanneson@bigpond.comCallum N. BaxterFormerly Greatland Pty LtdUnit 8, 175 Campbell St Belmont WAcbaxter@westleygrp.comSummaryThe high-grade Au-Cu Havieron deposit exhibits near coincident ovoid magnetic and gravity anomalies and was discovered in 2018, under 420 m of post-mineralisation cover, through geophysical modelling and drilling.At Havieron, the aeromagnetic image defines a 100 nT near-circular magnetic anomaly having a half-width of 800 m within generally bland magnetic terrain. Gravity data define an irregular gradient with values decreasing to the north east. Three large WNW trending sand dunes disrupt the Bouguer gravity image due to over-correction using the standard density of 2.67 gm/cc, but the disruption is reduced using a density of 1.50 gm/cc consistent with the notion that the dunes consist of loose dry sand. The revised gravity image shows an obvious bulge in the contours of the gravity gradient which appears asFigure 1.Havieron location map with regional aeromagnetics.a weak (0.5 mGal) irregular gravity ovoid in a residual gravity image. The peak of this ovoid is at least 200 m to the south ofDatathe magnetic peak. Including a remanent magnetic vector in the magnetic model simplified the model body and shifted itDetailed aeromagnetic data, collected along 50 m spaced NNE southward to a position coincident with the residual gravityflight lines at 40 m altitude and shown in Figure 2, define a anomaly. The discovery hole was designed to intersect thiscircular magnetic anomaly of about 100 nT with a half width coincident source of the magnetic and gravity anomalies. of 800 m within generally bland magnetic terrain. Images that follow also show collar locations for six of Newcrests historical Introduction HAC holes with surface traces if non-vertical.The Havieron gold-copper deposit is located 45 km east ofFigure 3 shows the topography which is a subset of the digital the large Telfer gold-copper mine in the Paterson Region ofelevation model created from the airborne data streams, northern Western Australia (Figure 1). The deposit is hostedindicating flat terrain interrupted by a number of WNW sand in Neoproterozoic age Lamil Group metasediments whichdunes. Coordinates are MGA Zone 51.consist of variably altered sandstones, siltstones and calc- The gravity data is a compilation of two surveys, yielding silicates. High grade gold and copper mineralisation wasmostly 100 x 100 m and 100 x 200 m spacings (shown as small discovered at Havieron under more than 400 m of Phanerozoicx symbols in Figure 4) that define an irregular gradient with age post-mineralisation cover via drill testing of a coincidentvalues decreasing to the north east. Three large WNW trending 100 nT magnetic and 0.5 mGal residual gravity anomaly. Current exploration drilling continues to expand the limits of mineralisation which has now been intersected over more than 1000 m of vertical extent. Havieron is an intrusion- related system with gold and copper mineralisation hosted in breccia, vein and massive sulphide replacement styles.The Havieron target was first recognised and drilled by Newcrest Exploration between 1991 and 2003 with most holes displaying alteration and low grade anomalous gold and copper mineralisation. Following re-evaluation of geophysical datasets Greatlands first hole in 2018, HAD001, intersected 121 m @ 2.9g/t gold and 0.23% copper from 497 m down hole. Other follow-up holes in 2018 were also supportive including HAD005 with two zones of mineralisation; upper of 103 m at 3.5g/t gold and 0.93% copper from 459 m, and a lower zone of 128 m at 7.4g/t gold and 0.54% copper from 680 m. Figure 2.Aeromagnetic data; sensor height 40 m.AUGUST 2022 PREVIEW 42'