Report on AP 2391 Nail Extended

Abstract

AP 2391, located 6 miles south of Tennant Creek, covers an area of 55 sq/m. The area was granted on the 23 September 1969 and renewed for a further 12 months in 1970. The intensive field programme continued on this AP with most of the work being concentrated on the N7 and N33 prospects. It was felt that a better understanding of these viz anomalies of the classic Tennant Creek type and a banded silicious ironstone, would make assessment and preparation of the remaining prospects more rational. N33 - Two diamond drill holes totalling 2,311 ft were drilled to test the body. The second hole collared 1,200 ft further west along the strike. N7 - Since there is about 60% outcrop in the N7 area, considerable time was spent in mapping and geochemical rock chip sampling so that as much information as possible could be collected before a full assessment was made. Mapping included 1/1000' scale followed by more detailed 1/200 scale using aerial photographs. A 1000 ft costean was trenched in an area of no outcrop and mapped at a scale of 1/40' to assist the interpretation. The first hole was drilled in slits, shales and sandstone sediments to a depth of 1545 ft. This ironstone stringers and quartz alteration were intersected near the target area. After additional fill-in gridding and magnetometry and a careful re-evaluation of the geological and magnetic targets a second hole was proposed 200 ft further east. This was completed at 1505'9'. Alteration consisted of quartz chlorite, quartz hematite and chlorite magnetite veining in brecciated silts and shales. The last 500 ft of core consisted of bedded sediments containing considerable amounts of finely disseminated magnetite. N35 Prospect - A small conical anomaly was located one mile south of N33 during ground magnetometry. Because of its shape and shallow depth to source, it was upgraded during the present programme to a point where it warranted additional work. A hole was drilled to a depth of 320 ft to test the magnetic target supplied by our consultant geophysicist. The drill intersected intense quartz chlorite alteration and finely desseminated magnetite before entering into a quartz feldsparegranitic rock. It is believed that this alteration zone may be completed and a re-interpretation of the propect is in progress.