Discovery of the Solomon iron deposits, Hamersley Province, Western Australia

Abstract

Channel iron deposits (CIDs) are Miocene pedogenic fluvial gravels comprised of predominately goethitic peloids and pelletoids derived from a highly ferruginous regolith. They currently supply over 40% by tonnage and over 50% by earnings of the seaborne iron ore trade out of the Hamersley Province of Western Australia. The two well documented, producing systems (Robe and Marillana palaeochannels) were both discovered during early reconnaissance mapping during the mid 1950s to early 1960s. Both crop out extensively over the majority of their length. The Solomon region was pegged by Fortescue Metals Group from late 2003 onwards on the basis that the area was dominated by the Brockman Iron Formation which hosts many Bedded iron deposits. There were also a number of previously mapped small isolated occurrences of supergene bedded and CID mineralisation within the general area. Analysis of publicly available data, and field confirmation of developing models led to the recognition of the Solomon palaeochannel system. Subsequent exploration defined a world-class resource of 2·9 Gt of iron ore mineralisation of which the great majority is buried CID. Apart from the Marillana CID system, the Solomon region is the only CID with significant tonnes of sub 2% alumina CID and with size over 500 Mt. Exploration has also outlined significant supergene bedded and detrital iron ore mineralisation.

Keywords:

• CHANNEL IRON DEPOSITS
• PALEOCHANNEL
• MINERAL DISCOVERY
• EXPLORATION TECHNIQUE
• IRON ORE