Eastern Tasmanian Margin: A Geophysical Study.
Honours Degree, 1997
University of Adelaide
The project area covers 89,000 km of the eastern Tasmanian continental margin. The main aims are to understand the tectonic development of the area, evaluate the potential for hydrocarbon exploration and determine whether gravity and magnetic data can be used to refine and constrain interpretation of seismic data. Seismic basement and top of Latrobe Group were interpreted on seismic sections over the entire area. The data coverage is sparse, approximately one line per 40km. Well control is provided by three wells in the southern Gippsland Basin, which were tied to a more recent seismic grid covering a small portion of the northern study area.
Gravity, magnetic and bathymetric data were used to complement and refine the seismic interpretation. Magnetic data were analysed using Automag and the gravity data were modelled using Potent. Swath images of the sea floor were useful in constraining trends of structures delineated from the sparse seismic grid. Integration of geophysical techniques has greatly improved confidence in seismic horizon picks on poor quality data.
Three maps were produce based interpretation of the seismic data set: a two way time map (including faults) to basement, an isochron of the Latrobe Group and an average sediment thickness map over the region. The margin is interpreted as a rifted margin formed during the separation of Australia from the Lord Howe Rise.
The area contains plausible source rocks and seals together with structural traps in the form of tilted fault blocks. Factor attributing to risks include postulated lack of reservoirs and thin sediment cover.