Annual report Eva Valley NT year ending 21-03-1988.

Abstract

Exploration Licence 4457 (Eva Valley) has been explored over the past twenty years by Geopeko Ltd, Nord Resources, Newmont Pty Ltd. and Billiton Australia. Previous exploration programs sought relatively large base metal and gold deposits. Exploration concentrated upon a banded iron formation (BIF) unit which can be traced for a distance of approximately 8 km. Four main prospects were identified, and some significant results were obtained, however they were largely not followed up due to 'size limitations'. Ken Day Pty Ltd as operator of a joint venture with Billiton, is specifically seeking smaller, economic gold and base metal deposits. Exploration this year, comprising mainly literature research, surface rock sampling and costeaning, has resulted in some very encouraging results from the gold-copper Copperflower Prospect. Encouraging indications were also obtained from the Ghost Gum Flats and Ludans Prospects. A low altitude multispectral remote sensing survey (Geo-Flite) was flown by Geo-Flite Research Pty Ltd covering the entire exploration licence. A considerable amount of work has been carried out by previous explorers and literature research has been an on-going process throughout the year. The results are summarised in the previous section. A complete set of 1:25,000 scale aerial photographs were acquired to aid in future geological mapping. Several reconnaissance field trips were undertaken to locate the prospects described in the literature. Fourteen reconnaissance rock samples were collected and assayed for Au, Cu, Zn, Pb, As and Sn. The Billiton grid over Twin Ridges was substantially reinstated and two detailed grids with 50m spacings were completed. Surveying was by hip chain and compass. Grids with 50m spacings and true north axes were surveyed over Ghost Gum Flats and Copperflower. A traverse was also measured along Ludans, and the adjoining Ludans Extended area. All grids were joined via a surveyed traverse and tied into previous mapping by Billiton. Base maps at 1:500 scale were prepared for Ghost Gum Flats and Copperflower and at 1:1000 scale in the Ludans and Twin Ridges prospects.

One hundred and eight rock samples were collected from the Ghost Gum Flats, Copperflower, Ludans and Twin Ridges areas. These samples were generally collected at random from an area of approximately 2m diameter, except for at Ludans where most were collected across the width of banded iron formation and siliceous gossan outcrop. All samples weighed approximately 3kg and were assayed for Au (fire assay) and Cu. Sample locations were plotted on the base maps. Seven costeans (A to G) totaling 710 m were excavated at 25 m intervals along the east-west grid lines across the Copperflower Prospect in the vicinity of the shaft. The costeans were approximately 0.6m wide and 2.5 to 3.0m deep. A further three costeans (H, J, K totaling 160m) were excavated in the Copperflower region along possible extensions of the mineralisation. Four costeans were excavated at Ghost Gum Flats (L, M, N and P) totaling 185m. Depth of the costeans averaged 1.5m. Horizontal channel samples were collected from all of the costeans. The channels were located as close to the base of the costeans as possible. Samples were taken at one metre intervals within the gossanous sections of the costeans, and at five metre intervals elsewhere. All samples were subsequently split and sent for assay. A total of 321, 1 to 3kg samples were sent for assay of Au, Cu, and Ag. Twenty-one of these samples from Copperflower were also assayed for Platinum and 16 of the samples from Ghost Gum Flats were also assayed for Pb, Zn and Sn. All the results have been appended and plotted on the base maps where appropriate. Additional rock samples were collected for possible later petrographical work.

The Copperflower costeans were geologically mapped and a reconnaissance geological map of the Copperflower area was completed. A number of one-day inspection field trips were made, during which further samples were collected, including three samples for metallurgical testing from Copperflower.