Geophysical insights into basement faults influencing basin evolution: A case study from Tennant Creek Block, North Australian Craton

Abstract

Geophysical interpretation and modelling of the poorly exposed Proterozoic basement rocks of the Tennant Creek Block in the North Australian Craton elucidated the distribution, location, connectivity, and overprinting relationships of regional faults. The prominent structural grain within the basement comprises west-northwest-striking faults that commonly bound geophysically defined domains of the Warramunga Formation and felsic plutons of the Tennant Creek Supersuite. Constrained by seismic reflection data, forward models of gravity and magnetic data identified several faults as major structures that link into a shallow south-dipping structure at approximately 20 km depth. The modelling also reveals a 20 km wide and 14 km southward deepening half-graben bounded by a northeast dipping normal fault. The half-graben forms a sub-basin filled with the Ooradidgee Group at the top of the basement stratigraphy. The west-northwest-trending structural grain of the basement is not reflected in the Tomkinson Creek Group in the overlying younger basin. The younger basin has dominant north-oriented faults and basement highs. This suggests basement structures had limited influence in controlling the evolution of younger basins in this region. Our approach has wider relevance, addressing similar challenges encountered in other cratonic areas globally, such as India and Africa, where sedimentary cover obscures critical aspects of basement architecture and tectonic evolution. This underscores the broader significance of our methodology in advancing the understanding of Precambrian terranes.