Sampling of material from water bores and auger holes, Darwin 1:250,000 sheet

Abstract

Open file drill logs of water bores and auger holes were examined to ascertain the extent of laterite development over those portions of the Darwin 1:250,000 Sheet area in which Lower Cretaceous sediments of the Mullaman Beds were reported as the underlying rocks. This study was undertaken to investigate the possibility that aluminous laterite might be capped by ferruginous laterite and might not be readily recognisable because of an absence of bauxitic pisolite development. Sections of several holes in which lateritic profiles were reported were selected for examination and sampling to determine whether aluminous essentially non pisolitic laterite (i.e. tubular) was present in these profiles. At the time of drill log review and sampling precise hole locations were not available. Drill hole location plans were later prepared and made available by the Mines Branch. A total of seventy nine 5 10 gm samples were taken from the Mines Branch reference material of the selected lateritic sections. These samples will be forwarded to Robertson Research in Bowral, N.S.W. for analysis for Al203, SiO2 and Fe203. Copies of results will be forwarded simultaneously to Pacminex fly Ltd in Sydney and the Northern Territory Mines Branch. If results indicate Al203 of possible economic significance additional analyses for available Al203, Reactive Si02 and loss on ignition may be requested, in which case similar arrangements for result despatch will apply.