EL 246 Spirit Hills, Annual report year ending 29-06-1974

Abstract

Exploration activity at the SE margin of the Bonaparte Gulf Basin was intensified in 1973/74, but field work had to be confined to ELs held by A.A.M. because the joint venture between A.A.M. and Placer-Conwest had not been approved by the Government at that stage. Previous work on this E.L., carried out before June 1973, included mapping and drilling (RANDOUR, R., May 1973 and RANDOUR, R. and D'AUVERGNE, P., August 1973). Results of exploration elsewhere in the Bonaparte Gulf Basin convinced A.A.M. to carry out an airborne magnetometer survey over large parts of the basin. This survey was flown by Geometrics

early in 1974. A total force G-803 Proton Magnetometer was used. Flying height was 100 m above mean terrain; line spacing was 500 m. The resulting Residual Magnetic Intensity contour map at a scale of 1:25,000 shows a magnetic trough which strikes approximately 300 and is clearly recognizable. It coincides with the Burt Range Syncline which separates the basement highs of the Pincombe Range in the W and the Precambrian mountains in the E. The E and W flanks of this trough show fairly steep magnetic gradients. If these coincide with steep slopes of the Burt Range Syncline, they could point to favourable environments for stratigraphical traps for metal-bearing brines. Indications at Spirit ilill are that this assumption could be correct. The magnetic contour map shows numerous minor flextures of contour lines whose significance is not readily understood. They could coincide with faults.

Field work in 1974/75 will make use of the valuable magnetic data and IP work and drilling will be to a certain extent guided by this information.