b'Conferences and eventsNewsPaleoproterozoic sequence of sedimentary rocks. Gold is primarily contained within several preferential stratigraphic host units, and within parasitic folds of the moderately ESE plunging Dead Bullock Soak anticlinorium. Geophysics has proven to be valuable in mapping stratigraphic markers and fold geometry which act as controls on gold mineralisation in the near-mine environment. Modern geophysical techniques have also been key in exploring for similar under-cover signatures across the larger brown-fields search-space, particularly when guided by a petrophysical characterisation of the conformable stratigraphic sequence. High resolution airborne magnetics allow for litho-structural interpretation across the region, which is predominantly under cover, as well as 3D modelling to guide drill targeting. Recent low-noise airborne gravity gradiometry surveys have provided data with sufficient resolution for gravity to be used as a complementary dataset on a prospect scale for both 2D and 3D geological interpretation and targeting. Airborne electromagnetics has been used to map carbonaceous units within the stratigraphic sequence, map the depth ofFigure 3.Modelled DCIP resistivity (top) and chargeability (bottom) sections cover, and alteration. Passive seismic (HVSR) methods haveacross the Atlntida deposit.also been deployed on a large scale to map the depth of cover. A depth of cover map generated from drilling, HVSR,Geophysical response of alteration and mineralisation and AEM allows for the effect of deep palaeochannelsat the Cadia Au-Cu porphyry system, NSWto be accounted for while interpreting affected datasets (both geophysical and geochemical). Acoustic impedanceTerry Hoschke (Alterrex)contrasts within the conformable stratigraphic sequence at DBS are sufficient to appear as significant seismic reflectors.Cadia is a large Au-Cu porphyry system located near OrangeA recent 3D seismic survey imaged the anticlinorium toin NSW, Australia. The system hosts several deposits includingdepth and down-plunge, and also mapped parasitic foldsCadia Hill, Cadia Quarry, Ridgeway and Cadia East, with a total along the limbs of the DBS anticlinorium that representresource in 2017 of 44Moz Au, 8.6Mt Cu and 55Moz Ag. exploration targets. Magnetic surveys are important in mapping alteration as magnetite can be present with distal alteration and form a halo around the deposits. Magnetite is not generally present You have got to confront cover head on, andwith the mineralisation, the exception being Ridgeway account for it, Tim Dohey. which is highly magnetic. Skarns and intrusions in the district can also be magnetic. Sulphides are typically zoned from bornite at the centre of the system to chalcopyrite to a pyrite halo. The pyrite halo is the likely cause of the IP anomaly at Ridgeway and Cadia East. The alteration is typically resistive. Geophysical response of the Atlntida Cu-Au porphyryThere can be pervasive feldspar and quartz alteration that deposit, Chile can be extensive, as can be observed above Cadia East and Ridgeway. The resistivity may be lower in the ore zone if Matthew Hope (First Quantum Minerals) there are sulphide veins. This is the case at Ridgeway where The discovery of the Atlntida Cu-Au-Mo porphyry depositin situ measurements and measurements on samples show is a recent example of exploration success under coverthe mineralised zone is relatively conductive. Geophysical in a traditional mining jurisdiction. Early acquisition oftechniques have proved useful in mapping alteration in geophysics was a key tool in the discovery, and in guidingthis system and have been involved in the discovery of some resource definition drilling, throughout the lifecycleof the deposits.of the project. Review of the geophysical response of the deposit with respect to its lithological distributionThe remainder of the deer: Geophysics and the and petrophysical properties has allowed it to be fullydiscovery of the southern extension of the Antler VMS characterised despite no mineralisation being exposed atDeposit, Arizona USAsurface. Data acquired over the project includes, induced polarisation, ground and airborne magnetics, gravimetryJarrad Trunfull (Terra Resources)and petrophysics.Located in mountainous terrain in Western Arizona USA, Antler is a high-grade stratabound Cu-Zn VMS deposit, with a Petrophysics is the decoder between thelong history of mining that stretches back to 1916. However, descriptive science of geology and theexploration efforts dwindled during the 1970s and there was no work done on the project for over 40 years. In 2020, New quantitative science of geophysics, World Resources re-invigorated the project with a renewed Matt Hope. focus on exploration, led by geophysics. Petrophysical 21 PREVIEW FEBRUARY 2022'