Final report year ending 14 July 1991 Gum Tree Hills

Abstract

The aeromagnetic survey outline 5 magnetic anomalies possibly indicative of kimberlitic diatremes. They were followed up by helicopter magnetics and loam sampling. 1 chromite was returned from the GH45-3 anomaly. It was of low interest. No other positive results were obtained.

3 anomalies (GH45-1, GH45-3 and GH34-1) were selected for follow up by ground magnetics. Modelling of GH45-1 suggested a broad (+300m), thick (+70m) body at approximately 70m depth. Percussion drilling of the anomaly intersected a dark grey magnetic clay without affinities to kimberlitic lithologies. Anomaly GH45-3 was determined to be sourced in surficial gravels. Modelling of anomaly GH34-1 indicated a source at 180-200m depth-this was too deep for drill testing.