Lineament Tectonics for Oil and Ore

In 1996 Primary Industries and Resources, South Australia (PIRSA) secured the services of Dr E.S.T. (Tim) O'Driscoll who is internationally acknowledged for his contributions to structural geology and lineament tectonics. He has become well known for his contribution to Australian continental lineament analysis. O'Driscoll is not alone in the field of lineament tectonics, but it is his unique and less publicised method of 'chicken track' lineament analysis which standout as one of the most remarkable and fruitful scientific breakthroughs in recent years.

Lineament tectonics was successfully used to target the Olympic Dam (Cu-Au-U-Rare Earth Elements) deposit (Lalor, 1987; O'Driscoll, 1988, Woodall, 1993, 1994). The discovery arose from innovative management of geological, geophysical and lineament teams. However, the significance of the role of lineament tectonics has only recently become known and accepted. Figure 1 demonstrates how remarkable O'Driscoll's work was. From an area of 31 000 km2 of the TORRENS and ANDAMOOKA 1:250 000 map areas, O'Driscoll's primary target accurately defined the orebody.

Relationship of the O'Driscoll lineament target to the subsequently discovered Olylmpic Dam orebody

Following the discovery of Olympic Dam, lineament analysis was used to identify a priority target in Queensland which now contains the Century lead-zinc deposit (Woodall, 1992). Unfortunately this target was overlooked at the time and it was not until almost 20 years later that CRA made the discovery, independently of the 'chicken track' lineament data. Similarly, the Boddington, Plutonic and Kanowna Belle gold deposits in Western Australia lie on previously defined lineament data (Woodall, 1991).

'Chicken Track' lineament analysis is a method of sampling components of regional discontinuities which are recognisable on air photo mosaics. 'Chicken Track' data are then combined with other information used for exploration to identify lineament targets. In particular, the SAEI (South Australian Exploration Initiative) aeromagnetic surveys played an integral role in lineament analysis. It is from the combination of all of the geologically significant data that lineaments can be extracted and, ultimately, targets such as those encompassing Olympic Dam or Century are identified. This final step is an intensive process requiring the lineaments and host rocks to meet numerous criteria.

PIRSA began a project in 1996 to cover petroleum and mineral provinces within South Australia. O'Driscoll worked with petroleum geologist Rodney Boucher who has completed a Ph.D. on lineament tectonics. A pilot project was completed over the northern Adelaide Geosyncline followed by studies in the Cooper Basin area. The results of these studies are now available as two PIRSA reports - "Lineament Tectonic Data, South Australia, with a Focus on the Cooper Basin", October 1997, Report Book 97/39 and "Lineament Associations in the Cooper Basin Region, South Australia: Basement Controls on Hydrocarbon Distribution", September 1998, report Book 98/00030

References:

Lalor, JH, 1987. The Olympic Dam copper-uranium-gold-silver deposit, South Australia. In: Horn, MK (Ed), 4th Circum-Pacific Energy and Mineral Resources Conference, Singapore, 1986. Transactions, pp 561-567 

O'Driscoll, EST, 1988. Lineament tectonics in ore search, with examples including Olympic Dam. Australian Mineral Foundation course 563/88 (unpublished).

Woodall, R, 1991. WMC's Australian mineral exploration: yesterday, today and tomorrow. Western Australian Geoscientific Technical Conference, Perth, 1991 (unpublished)

Woodall, R, 1992. Empiricism and concept in successful exploration. In: 11th Australian Geological Convention, Ballarat, 1992. Geological Society of Australia. Abstracts, 32:49-51

Woodall, R, 1993. The multidisciplinary team approach to successful mineral exploration. Society of Economic Geologists. Newsletter. 14:1-6

Woodall, R, 1994. Empiricism and concept in successful mineral exploration. Australian Journal of Earth Sciences, 41(1):1-10