RE: Havieron lookalikes13 Jan 2022 14:05
In terms of Olympic Dam-type mineralisation the relationship between gravity and magnetic sources is comparable, however the amplitude of the gravity anomaly is considerably lower at Tabletop1 (0.5mgal vs >10.0mgal). Similarly the density contrast is lower, which suggests that if the Tabletop1 gravity anomaly is due to haematitic alteration, the alteration is not as intense as at Olympic Dam.
In terms of Telfer-style mineralisation it has been suggested that the gravity anomaly may arise from sulfides within sediments above an intrusive source. While this is possible – with a density contrast of 0.05g/cc indicating that approximately 1.1% sulfides could give rise to the gravity anomaly, it is noted that no gravity anomaly is evident over Telfer, nor is it directly underlain by a magnetic intrusive (Sexton, 1994).
Regardless, there is a very interesting empirical relationship between the magnetic and gravity anomalies. In order to determine the source of the gravity anomaly a hole should be drilled to a vertical depth of at least 1000 metres, and possibly to 1200 metres, into the core of the dense source.