Bulletin of the Geological Society of Malaysia, Volume 33, Nov. 1993, pp. 357-368
School of Earth Sciences, The University of Melbourne, Parkville, Victoria 3052, Australia
Abstract: An investigation of the crustal lineament framework was undertaken in northwestern Australia, an important mineral and hydrocarbon province. The Australian continental scale lineament framework was examined so that northwestern Australia could be understood in terms of the larger regional picture.
E.S. Hills identified a number of mega morphological lineaments using a “Great Relief Model” of Australia. His morphological lineaments often coincided with deeper gravity lineaments interpreted by both Australian lineament researcher, E.S.T. O‘Driscoll, and the author. O‘Driscoll used a number of data sets including a diffused gravity image of Australia to interpret a network of continental scale lineaments.
Continental scale gravity lineaments can be verified by their response in the rock record. Examples are given along the west-northwest trending G3 lineament and the north-northeast trending G5. In northwestern Australia, the G3 and G5 are coincident with the King Leopold and Halls Creek Mobile Zones respectively. These mobile zones have undergone a reactivation history from the Early Proterozoic/Archean through to the Late Palaeozoic/Mesozoic. An influence of the G3 on the faulting pattern of the Arunta Block in Central Australia and the Sydney Basin region of eastern Australia can be observed. The G5 can be traced offshore in a north-northeast direction through the Arafura Basin where it is coincident with the ancient, reactivated Lyndoch Bank Fault System. The east-northeast trending Malita Graben terminates against the western edge of the G5 and swings into a parallel north-northeast orientation becoming the Calder Graben. The regional tectonics of northwestern Australia, both onshore and offshore, relate closely to the distribution of gravity lineaments in this region.
A spatial distribution relationship exists between the continental scale lineaments and major petroleum and mineral discoveries in Australia. Lineament intersections are of particular importance where it appears that the required geological conditions for economic deposits are most favourable. The same relationship can be observed in northwestern Australia, particularly between lineament intersections and major petroleum, base metal and diamond occurrences. The significant economic discoveries of the Challis and Jabiru oilfields occur at the intersection of the northwest trending G11 with the north-south orientated NS1 lineament. Onshore, the NS1 lineament is coincident with the only significant Canning Basin oil discoveries together with the Ellendale and Noonkanbah diamondiferous lamproites. At a local scale, a sinistral flexure termed by O‘Driscoll a “Tethyan Twist”, is often interpreted as economic discoveries where a west-northwest lineament intersects the host rock or mineral deposit.