• Earth Sciences
• Energy
• Energy Exploration
• Geology
• Geophysics
• Marine Geoscience
• Seismology And Seismic Exploration

• EPP 6
• EPP 10
• EPP 11

• Bight Basin
• Duntroon Basin
• Eucla Basin

Notes: Includes the following reports and abstracts:  - 1974 marine seismic surveys, R-8 and R-9, interpretation report. This seismic interpretation report includes a reinterpretation of all pre-R 8 survey data, and is based on a new model of...

Notes: Includes the following reports and abstracts:  - 1974 marine seismic surveys, R-8 and R-9, interpretation report. This seismic interpretation report includes a reinterpretation of all pre-R 8 survey data, and is based on a new model of fault style in the deep water acreage. The new model was conceived in the western part of EPP 11 where a denser seismic grid became locally available as a result of the R 8 survey. As part of the R 8 programme, 40 line km of detail seismic were recorded over the Quokka lead in the southeastern Duntroon Embayment, yielding an improvement on the 1973 R 7 survey data, especially after velocity analysis filtering in the shallower section, this gain being attributed to the higher reflection multiplicity. The Quokka lead is bounded to the northeast and southwest by two major normal faults of considerable throw at basement level. In this area basement is overlain by a probable lower Cretaceous section consisting of the stratigraphic equivalent of the Echidna shales possibly followed by the Platypus sands subcropping against the base Tertiary. The mapped Cretaceous horizon lies within the latter interval. Closure at the mapped horizon depends on the presence of, and sealing against, an east-west split of the southwestern bounding fault which is thought to exist at basement level. Unfortunately, the data quality is not sufficiently good to position this split or define its movement at the level of the mapped horizon, and the bounding faults likewise do not offer any evidence as to whether the main fault movement pre or post-dated the mapped horizon. The Quokka lead has therefore been abandoned as carrying too high a structural risk.Interpretation of 644 line km of seismic data recorded by the R 9 survey in EPPs 10 and 11 during October-November 1974 has reduced the number of structural leads compared with the previous interpretation, especially in EPP 11 where only one significant lead, Galah, remains. In EPP 10 several structures with likely closure could not be confirmed whilst others, notably Rosella, proved to be more complicated than originally presumed. The major lead in EPP 10, Jabiru, remains somewhat tenuous due to the generally poor data quality and locally strong shallow reflections which screen off the deeper data in this area. Whilst some improvement in data quality over previous surveys was obtained in the Jabiru area, the improvement was not sufficiently great to allow a reliable map to be made. Notes: Shell Development report no. SDA 193. For the survey data acquisition and processing contractor's final operations reports, see Env 2351 (R 8 survey) and Env 2558 (R 9 survey).   - 1974 marine seismic survey, R-9, interpretation report. This report deals with the interpretation of 337 line km of R 9 seismic survey data recorded in the western portion of EPP 6 during October-November 1974. The data covers a major zone of intense, basement-controlled faulting marginal to the stable Gawler Craton, within which the objective Cenomanian-Albian sedimentary section is strongly downthrown to great depths. The objective of this part of the R 9 survey programme was to establish a sufficiently dense grid of reflection coverage in this area to enable the structural style in the Cretaceous section to be studied in detail. 10 lines were shot in an area of 30 x 40 km, giving a grid density of 5 km. Water depths ranged from 850 to 1650 m. Between 5 and 6 seconds of reflections from below the seabed were recorded, and were judged to be of generally good quality. Recording and processing parameters were the same as for the remainder of the R 9 survey in EPPs 10 and 11.Three Mesozoic stratigraphic horizons were mapped in time in an unsuccessful search for a viable structural lead at an objective level that could be correlated either east to Platypus 1 or west to Potoroo 1. Nevertheless, the results of the interpretation have enabled new models of structural style and basin setting to be postulated for this part of the Bight and Duntroon Basins. Two distinct styles of faulting, basement-controlled and growth-type, have been recognised, and a late Cretaceous phase of anticlinal deformation has been established. Notes: Shell Development report no. SDA 206. See also Env 02351
Geographic Locality: Southern Ocean;Great Australian Bight;1974 R 8 Marine Seismic Survey;1974 R 9 Marine Seismic Survey
Doc No: Env 02544

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