Geoscience Visual Presentation G04: Distribution, timing and origin of magmatism within the sedimentary basins of the western Australian continental margin

Geoscience Visual Presentation G04 The energy-rich western Australian continental margin is considered to be an archetypal volcanic rifted margin, though a systematic spatiotemporal analysis of magmatic activity is lacking. We present a comprehensive margin-wide investigation of the dominantly mafic magmatic activity within the inboard sedimentary depocentres (from the Bonaparte Basin in the north to the Mentelle sub-basin in the south), where the preserved stratigraphic record and subsurface data coverage enable new insights into the distribution, timing and nature of the igneous record, and its impact on basin properties and prospectivity. In contrast to the Northeast Atlantic margin, where voluminous, margin-wide igneous activity occurred within a narrow time interval, magmatism along the western Australian margin is more protracted (spanning >100 Myr) and spatially variable. Initial magmatic activity, encompassing both intrusions and extensive subaerial and submarine volcanic deposits, was concentrated in the Canning and Roebuck Basins during late Permian to mid-Triassic rifting. Following a period of reduced igneous activity, the locus of magmatism (and active rifting) migrated to the Browse Basin during the early-mid Jurassic, characterised by widespread intrusive and extrusive activity, coeval with the deposition of prolific fluvio-deltaic reservoirs. During the late Jurassic, contemporaneous with the breakup of the Argo microcontinent, magmatic activity was concentrated in the Carnarvon Basin, characterised by complex networks of sill and dyke intrusions and rarely preserved volcanic activity. As the locus of rifting progressively migrated to the south, the final phase of extensive igneous activity along the margin was concentrated in the Mentelle sub-basin during the early Cretaceous. To access the Visual Presentation click on 'Supplementary data' below. To read the full paper click here