This Otway Basin dataset contains descriptive attribute information for the areas bounded by the relevant spatial groundwater feature in the associated Hydrogeology Index map. Descriptive topics are grouped into the following themes: Location and administration; Demographics; Physical geography; Surface water; Geology; Hydrogeology; Groundwater; Groundwater management and use; Environment; Land use and industry types; and Scientific stimulus.
The Otway Basin is an elongated sedimentary basin located on the south-east continental margin of Australia. Covering approximately 150,000 square kilometres and stretching about 500 km from South Australia's Cape Jaffa to Victoria's Port Phillip Bay and Tasmania's north-west, most of the basin is offshore, with a smaller portion onshore.
Geological studies of the Otway Basin have primarily focused on its hydrocarbon prospectivity, examining thick Cretaceous aged rocks both onshore and offshore. However, the shallower onshore sedimentary units are more relevant from a groundwater perspective.
The basin's formation began with rifting between the Australian and Antarctic plates during the Late Jurassic, leading to regional subsidence and the development of the elongated sedimentary basin. Following the Cretaceous plate breakup, a passive margin basin formed, which subsequently underwent basin inversion, reverse faulting, and folding, interspersed with extensional periods and normal faulting. This complex evolution, combined with sea level variations and volcanic activity, resulted in numerous sedimentary cycles.
The sedimentary succession in the basin comprises non-marine sediments and volcanic rocks from the Jurassic and early Cretaceous, with a period of tectonic compression interrupting sedimentation during the mid-Cretaceous. The late Cretaceous and Cenozoic sedimentary and volcanic rocks form the primary groundwater-bearing aquifers of the basin, with various sedimentary environments developing in the Neogene and Quaternary. The basin's structural geology is intricate, with numerous basement highs, sub-basins, troughs, and embayments. Fault systems are prevalent, separating tectonic blocks and potentially influencing groundwater flow, offering conduits for inter-aquifer connectivity.
Overall, the Otway Basin's geological history has shaped its hydrocarbon potential and groundwater resources, making it an essential area for ongoing research and exploration in Australia's geological landscape.
