Partial relinquishment report on EL 7190 (Hodgson Downs), February 1994

Abstract

Exploration for diamonds, base metals and gold was carried out over the relinquished portion of EL 7190. Thematic Mapper imagery and air photos were examined prior to the commencement of fieldwork. No anomalous features thought indicative of ultramafic intrusives were observed. Reconnaissance heavy mineral stream sediment sampling for diamonds was completed, and possible kimberlitic indicator minerals, mainly being spinels, were obtained from a number of samples draining breakaways of Cretaceous rocks. Infill samples were collected, which confirmed the anomalous nature of a number of catchments. Rare kimberlitic compositions were obtained, but results were not encouraging enough to warrant further diamond exploration. The indicator minerals are of low interest and probably being derived from a secondary source of Cretaceous sediments. It is most unlikely that they are derived from a proximal diamondiferous ultramafic source rock. The reconnaissance geochemical data revealed only weakly anomalous values in an environment which does not seem very conductive to mineralisation, and only a limited geochemical programme was carried out in 1992 within the relinquished portion. This programme involved stream sediment BLEG and rock chip sampling, which did not reveal any anomalous results.