oa The Waterloo and Amorac nickel deposits, Western Australia: A geophysical case history

The Waterloo and Amorac nickel sulphide deposits are significant discoveries located in the north eastern goldfields region of Western Australia. They were found as a result of the systematic application of geophysical techniques during a green fields exploration program. The deposits are 300m from each other, blind, and are overlain by 80m of deeply weathered basement rocks. Despite their close proximity, the deposits are quite separate and different in style.

Interpretation of detailed aeromagnetic data was first used to delineate komatiite-basalt contacts of interest for nickel sulphide exploration. Then these contacts were surveyed with a moving loop TEM survey (Inloop and Slingram receivers) which delineated nine basement conductors. Finally, fixed loop TEM surveys were used to better define the targets for drill testing.

Drill hole TEM surveys have been used since the discovery to guide drilling and better define the mineralisation size, location, orientation, and character. Complicated geometry and multiple conductive sources make careful interpretation and modelling essential.