The tectonostratigraphic history of the Proterozoic Northern Lawn Hill Platform, Australia: an integrated intracontinental basin analysis

The Northern Lawn Hill Platform (NLHP) comprises an area of approximately 16,000 km(2) in north-central Australia. Thick packages of Proterozoic strata outcrop in the region, although large areas are also covered by younger strata. The packages contain basin sediments and igneous rocks that span similar to 400 m.y. We present a regional synthesis of approximately 150 m.y. of the tectonostratigraphic history of the area which hosts several world-class base metals deposits. The interpretation is based primarily on a sequence stratigraphic and structural interpretation of seismic data, a common approach in the petroleum resource sector, but rare in analyses of mineral resources. Models of subsurface geology and a basement template are provided using observed geopotential data that are iteratively calibrated with other data. Geochronological, palaeomagnetic, geochemical and sequence stratigraphic investigations on outcrop and drill core also are integrated into the history. The seismic data allow separated outcrop belts to be confidently correlated for the first time. Geochronological data control the basin history delineated by this interpretation. Palaeomagnetic data allow the results presented here to be extrapolated regionally and globally. Although considered to be deposited on entirely intracontinental lithosphere, the basin phases record significant fluctuations in the volume and geometry of accommodation space for sedimentation. Multiple pulses of deformation are recorded by changing depositional geometries. We propose a history of re-activation of a basement template and speculate on geodynamical mechanisms for accommodation space fluctuations and geometric variability. The detailed understanding of the basin evolution of the NLHP gained by integrated basin analysis provides a powerful tool for predictive fluid flow models as an aid to resource exploration. It should also provide a useful analogy in understanding tectonic processes and basin evolution of other similar aged intracontinental basins. (C) 1998 Published by Elsevier Science B.V. All rights reserved.