NEW IDEAS ON THE RIFTING HISTORY AND STRUCTURAL ARCHITECTURE OF THE WESTERN OTWAY BASIN: EVIDENCE FROM THE INTEGRATION OF AEROMAGNETIC, GRAVITY AND SEISMIC DATA

1994 ◽  
Vol 34 (1) ◽  
pp. 529 ◽  
Author(s):  
G.W. O'Brien ◽  
C.V. Reeves ◽  
P.R. Milligan ◽  
M.P. Morse ◽  
E.M. Alexander ◽  
...  
Keyword(s):  
Seismic Data ◽  
Normal Fault ◽  
Magnetic Data ◽  
Data Sets ◽  
Stress Regime ◽  
Petroleum Potential ◽  
History Of ◽  
New Ideas ◽  
Structural Architecture ◽  
Great Australian Bight

The integration of high resolution, image-processed aeromagnetic data with regional geological, magnetic, gravity and seismic data-sets has provided new insights into the structural architecture, rifting history, and petroleum potential of the western onshore and offshore Otway Basin, south-eastern Australia.Three principal structural directions are evident from the magnetic data: NS, NE-ENE and NW-WNW. The structural fabric and regional geological data suggest that the rifting history of the basin may have taken place in two distinct stages, rather than within a simple rift-to-drift framework. The initial stage, from 150 to ~120 Ma, took place within a stress regime dominated by NW-SE extensional transport, similar to that of the basins within the Great Australian Bight to the west. ENE-striking extensional rift segments, such as the Crayfish Platform-Robe Trough and the Torquay Sub-Basin, developed during this period, contemporaneous with the deposition of thick sediments of the Early Cretaceous (Tithonian-Hauterivian) Crayfish Subgroup. In other parts of the basin, NW-striking rift segments, such as the Penola, and perhaps Ardonachie, Troughs onshore, developed within a strongly trans-tensional (left-lateral strike-slip) environment. At ~120 Ma, the regional stress field changed, and the Crayfish Subgroup-aged rift segments were reactivated, with uplift and block faulting extending through to perhaps 117 Ma. Rifting then recommenced at about 117 Ma (contemporaneous with the deposition of the Barremian-Albian Eumeralla Formation), though the extensional transport direction was now oriented NNE-SSW, almost perpendicular to that of the earlier Crayfish Subgroup rift stage. This later rift episode ultimately led to continental breakup at ~96 Ma and produced the 'traditional' normal fault orientations (NW-SE to WNW-ESE) throughout the Otway Basin.

Petroleum potential of the offshore southern Carnarvon Basin—insights from new Geoscience Australia data

2011 ◽  
Vol 51 (2) ◽  
pp. 746
Author(s):  
Irina Borissova ◽  
Gabriel Nelson
Keyword(s):  
Seismic Data ◽  
Source Rocks ◽  
Magnetic Data ◽  
Long Distance ◽  
Potential Field Data ◽  
Petroleum Potential ◽  
Gravity And Magnetic ◽  
Gravity And Magnetic Data ◽  
Insight Into ◽  
Carnarvon Basin

In 2008–9, under the Offshore Energy Security Program, Geoscience Australia (GA) acquired 650 km of seismic data, more than 3,000 km of gravity and magnetic data, and, dredge samples in the southern Carnarvon Basin. This area comprises the Paleozoic Bernier Platform and southern part of the Mesozoic Exmouth Sub-basin. The new seismic and potential field data provide a new insight into the structure and sediment thickness of the deepwater southernmost part of the Exmouth Sub-basin. Mesozoic depocentres correspond to a linear gravity low, in water depths between 1,000–2,000 m and contain between 2–3 sec (TWT) of sediments. They form a string of en-echelon northeast-southwest oriented depressions bounded by shallow-dipping faults. Seismic data indicates that these depocentres extend south to at least 24°S, where they become more shallow and overprinted by volcanics. Potential plays in this part of the Exmouth Sub-basin may include fluvio-deltaic Triassic sandstone and Lower–Middle Jurassic claystone source rocks sealed by the regional Early Cretaceous Muderong shale. On the adjoining Bernier Platform, minor oil shows in the Silurian and Devonian intervals at Pendock–1a indicate the presence of a Paleozoic petroleum system. Ordovician fluvio-deltaic sandstones sealed by the Silurian age marine shales, Devonian reef complexes and Miocene inversion anticlines are identified as potential plays. Long-distance migration may contribute to the formation of additional plays close to the boundary between the two provinces. With a range of both Mesozoic and Paleozoic plays, this under-explored region may have a significant hydrocarbon potential.

Seismic, gravity and magnetics, a complementary geophysical study of the Paqualin Structure, Timor Sea, Australia

1989 ◽  
Vol 20 (2) ◽  
pp. 25 ◽  
Author(s):  
P.M. Smith ◽  
M. Whitehead
Keyword(s):  
Seismic Data ◽  
Gravity Data ◽  
Seismic Survey ◽  
Magnetic Data ◽  
Data Sets ◽  
Intrusive Body ◽  
Geophysical Study ◽  
Timor Sea ◽  
Susceptibility Contrast ◽  
Gravity And Magnetic Data

The presence of a large anomalous structure in the northern part of Permit AC/P2 in the Timor Sea has been recognised ever since seismic data were first acquired in the area. Historically, however, sparse seismic coverage has always prevented a detailed and unambiguous interpretation of the complicated structure. In order to overcome this problem, some 2000 km of 3D seismic data were acquired over the feature. In conjunction with this seismic survey, detailed gravity and magnetic data sets were also recorded over the structure.Interpretation of the new seismic data indicated the presence of a piercement structure which is associated with a small negative Bouguer gravity anomaly and a magnetic intensity anomaly resulting from a positive susceptibility contrast. Modelling of the magnetic data indicated that an acidic or intermediate intrusive body was the most likely cause of the piercement structure. The presence of an acidic intrusive body was consistent with the gravity data which indicated that no large density contrast existed between the material of the piercement structure and the surrounding sediments.The combined interpretation of these three data sets was tested by a well, Paqualin-1, drilled on the flank of the piercement structure. The well encountered a thick evaporite sequence with associated thin bands of magnetitie and intermediate igneous rocks. It was logged with a three component downhole magnetic probe and forward magentic modelling work incorporating the results of the magnetic log gave good agreement with the observed aeromagnetic profiles.

STRUCTURE AND STRATIGRAPHY OF THE CEDUNA TERRACE REGION, GREAT AUSTRALIAN BIGHT BASIN

1979 ◽  
Vol 19 (1) ◽  
pp. 53 ◽  
Author(s):  
A. R. Fraser ◽  
L. A. Tilbury
Keyword(s):  
Upper Cretaceous ◽  
Single Channel ◽  
South Australia ◽  
Magnetic Data ◽  
The West ◽  
Petroleum Potential ◽  
Northern Margin ◽  
Gravity And Magnetic ◽  
Gravity And Magnetic Data ◽  
Great Australian Bight

The Ceduna Terrace is a bathymetric feature covering some 70,000 sq km, in the continental slope of South Australia. Its most gently sloping part lies between the 500 and 2500m isobaths, and is underlain by the main depocentre of the Great Australian Bight Basin.A systematic interpretation of the region has been made, based on 17,000 km of multi-channel seismic data from Shell surveys, 8000 km of single-channel seismic, gravity and magnetic data from the BMR Continental Margins Survey, and 6000 km of gravity and magnetic data from surveys by Lamont-Doherty Geological Observatory. Seismic ties were made to the wells Potoroo-1 and Platypus-1.Mapping of the key seismic horizons confirms the picture of the basin as a sedimentary wedge, more than 10 km thick, extending from the edge of the shelf to the continental rise. Three important unconformities can be mapped over a wide area and tied to Potoroo-1 well-a basement reflector separating Lower Proterozoic crystalline rocks of the Gawler Craton from an overlying, block-faulted sequence of mainly Lower to mid-Cretaceaus sediments; an unconformity at the base of an Upper Cretaceous sequence which includes a major prograded unit in the west; and a break-up unconformity at the base of a Tertiary marine transgressive sequence, that, in turn, is overlain by marine carbonate deposits. Widespread shallow marine sediments are believed to exist in the west of the basin, in both the Lower and Upper Cretaceous sequences.Structure is dominated by normal, west to NW trending, down-to-the-south faults, many of which are synsedimentary. Fault displacements are greatest beneath the shelf-break, where basement has been downthrown 5 to 6 km. Farther south, synsedimentary faulting has resulted in a marked thickening of both Upper and Lower Cretaceous sequences.The basin has been barely explored for hydrocarbons. Regional seismic coverage is good, but drilling in the main part of the basin is limited to one well on the northern margin. The petroleum potential of the western half of the basin is rated as good, in view of the interpreted existence of abundant marine source beds and the recognition of situations favourable for generation, migration and entrapment of hydrocarbons.

A REVIEW OF GEOPHYSICAL EXPLORATION IN THE POLDA BASIN, SOUTH AUSTRALIA

1986 ◽  
Vol 26 (1) ◽  
pp. 319
Author(s):  
R.G. Nelson ◽  
T.N. Crabb ◽  
R.A. Gerdes
Keyword(s):  
Magnetic Material ◽  
South Australia ◽  
Magnetic Data ◽  
History Of ◽  
Magnetic Basement ◽  
Central Australia ◽  
Intracratonic Basin ◽  
Seismic Sections ◽  
Great Australian Bight ◽  
Block Faulting

The Polda Basin is an intracratonic basin, at least 5000 m in depth, extending from the edge of the Great Australian Bight nearly 400 km east to the centre of Eyre Peninsula in southern South Australia, it can now be recognised as a structural feature of some antiquity, originating possibly as a crustal downwarp in Proterozoic time during the same orogenic regime that gave rise to the Officer and Amadeus basins of central Australia, with which it has strong affinities. Its internal structure indicates that it has been subject to the same orogenic episodes that have affected southern and central Australia, culminating in rotational block faulting associated with the final pull-apart of Gondwanaland. Extensive salt mobilisation observed on seismic sections, confirmed by the drilling of the Mercury 1 and Columbia 1 wells, supports the concept of the basin's Cambrian or Precam-brian origins.The exploration history of the basin is a useful example of the application of a number of geophysical disciplines to arrive at a satisfactory interpretation. A reappraisal of geophysical data was undertaken after Outback Oil N.L. drillhole Gemini 1 penetrated 'uneconomic' basement at 856 m, far short of the anticipated sedimentary section of 1830-2440 m. Interpretation of shipborne magnetic data, not previously considered, indicated that a seismic horizon close to where Gemini 1 penetrated igneous rock was related to a thin layer of magnetic material which did not correspond to deep magnetic basement. Further detailed aeromagnetic and seismic studies confirmed this interpretation, which was tested by the drilling of two exploration wells. Mercury 1 and Columbia 1. Although unsuccessful as hydrocarbon discovery wells, these two wells confirmed the overall validity of the interpretation. Stratigraphic information derived from these wells and from further geophysical studies and drilling onshore have led to a new assessment of the basin and its potential.

Westhazel General Petroleums Pool: Case history of a salt‐dissolution trap in west‐central Saskatchewan, Canada

Geophysics ◽  
1993 ◽  
Vol 58 (6) ◽  
pp. 889-897 ◽  
Author(s):  
Neil L. Anderson ◽  
Dale A. Cederwall
Keyword(s):  
Seismic Data ◽  
Lower Cretaceous ◽  
Gravity Data ◽  
Data Sets ◽  
West Central ◽  
Geophysical Techniques ◽  
Salt Dissolution ◽  
Diagnostic Signature ◽  
History Of ◽  
Push Down

The Westhazel General Petroleums (GP) Pool of west‐central Saskatchewan, Canada, produces from the GP member of the Lower Cretaceous Mannville Group. This reservoir is structurally closed across the updip, eastern dissolutional edge of the underlying Middle Devonian rock salt of the Leofnard Member, Prairie Formation. The leaching of these salts occurred in post‐Mannville time in the Westhazel area and caused the regional southwest dip of the General Petroleums member to be locally reversed. The Westhazel GP Pool, from a geophysical perspective, is characteristic of many of the shallow Lower Cretaceous pools situated along the dissolutional edge of the Prairie salt. The thin, 10 m reservoir facies at Westhazel does not exhibit a diagnostic signature on either seismic or gravity data. Rather, it is the updip edge of the salt across which the reservoir is closed that can be mapped using geophysical techniques. On seismic data, the dissolutional edge of the Prairie salt is characterized by: (1) a subtle decrease in the amplitude and lateral coherency of the underlying Winnipegosis event; (2) a gradual thinning of key encompassing Paleozoic intervals; (3) dip reversal along the Beaverhill Lake (Late Devonian) event; (4) dip reversal along the Mannville (Lower Cretaceous) event; and (5) time‐structural “push down” of Lower Cretaceous and underlying reflections in areas of recent salt dissolution. On the gravity profile, the edge of the salt is manifested as a 1.5 mGal anomaly. The interpretation of both geophysical data sets is consistent with available geologic control.

Holocene earthquake history and slip rate of the southern Teton fault, Wyoming, USA

2019 ◽  
Vol 132 (7-8) ◽  
pp. 1566-1586 ◽  
Author(s):  
Christopher B. DuRoss ◽  
Ryan D. Gold ◽  
Richard W. Briggs ◽  
Jaime E. Delano ◽  
Dean A. Ostenaa ◽  
...  
Keyword(s):  
Slip Rate ◽  
Normal Fault ◽  
Alluvial Fan ◽  
Early Holocene ◽  
Data Sets ◽  
History Of ◽  
Teton Range ◽  
Geomorphic Surfaces ◽  
Fault Record ◽  
Earthquake Cycles

Abstract The 72-km-long Teton normal fault bounds the eastern base of the Teton Range in northwestern Wyoming, USA. Although geomorphic surfaces along the fault record latest Pleistocene to Holocene fault movement, the postglacial earthquake history of the fault has remained enigmatic. We excavated a paleoseismic trench at the Buffalo Bowl site along the southernmost part of the fault to determine its Holocene rupture history and slip rate. At the site, ∼6.3 m of displacement postdates an early Holocene (ca. 10.5 ka) alluvial-fan surface. We document evidence of three surface-faulting earthquakes based on packages of scarp-derived colluvium that postdate the alluvial-fan units. Bayesian modeling of radiocarbon and luminescence ages yields earthquake times of ca. 9.9 ka, ca. 7.1 ka, and ca. 4.6 ka, forming the longest, most complete paleoseismic record of the Teton fault. We integrate these data with a displaced deglacial surface 4 km NE at Granite Canyon to calculate a postglacial to mid-Holocene (14.4–4.6 ka) slip rate of ∼1.1 mm/yr. Our analysis also suggests that the postglacial to early Holocene (14.4–9.9 ka) slip rate exceeds the Holocene (9.9–4.6 ka) rate by a factor of ∼2 (maximum of 3); however, a uniform rate for the fault is possible considering the 95% slip-rate errors. The ∼5 k.y. elapsed time since the last rupture of the southernmost Teton fault implies a current slip deficit of ∼4–5 m, which is possibly explained by spatially/temporally incomplete paleoseismic data, irregular earthquake recurrence, and/or variable per-event displacement. Our study emphasizes the importance of minimizing slip-rate uncertainties by integrating paleoseismic and geomorphic data sets and capturing multiple earthquake cycles.

The use of geologic expression workflows for basin scale reconnaissance: A case study from the Exmouth Subbasin, North Carnarvon Basin, northwestern Australia

2014 ◽  
Vol 2 (1) ◽  
pp. SA163-SA177 ◽  
Author(s):  
N. J. McArdle ◽  
D. Iacopini ◽  
M. A. KunleDare ◽  
G. S. Paton
Keyword(s):  
Seismic Data ◽  
Regional Scale ◽  
Normal Fault ◽  
Seismic Attributes ◽  
Data Sets ◽  
Seismic Attribute ◽  
Data Set ◽  
Attribute Analysis ◽  
Basin Scale ◽  
Northwestern Australia

The focus of this study is to demonstrate how seismic attributes can be used in the interpretation workflow to rapidly obtain a high-resolution view of the geology that is imaged within a seismic data set. To demonstrate the efficacy of seismic attribute analysis to basin scale reconnaissance, we apply a workflow to seismic data sets from the Exmouth Subbasin, northwestern Australia, with the aim of determining the geologic expression of the subsurface. Of specific interest are Barrow Group Jurassic and Cretaceous fluvial and marine sediments, that were faulted during the Jurassic-Cretaceous rifting associated with the breakup of East Gondwana. Regional-scale interpretations are made to develop a tectonostratigraphic context to the investigation. Target-level analyses, focused on features of exploration interest identified using regional reconnaissance, are made to calibrate attribute response and demonstrate the effectiveness of seismic attributes for rapid evaluation of prospectivity in the initial stages of exploration. The main structural episodes are distinguished using dip and azimuth attributes, and faulting is expressed using a combination of edge attributes which are used to create fault trend lineations. We observe three main structural trends: the main northeast–southwest Jurassic-Cretaceous syn-rift primary fault orientation of 48°, a secondary trend of 108°, taken to represent secondary conjugate faulting and a third trend of 100° interpreted as the reactivation of these faults into the postrift sediments. Stratigraphic attributes that respond to amplitude and frequency are used to create reservoir scale geobodies of faulted Macedon turbidites, which in turn are used for detailed tuning sensitivity analysis. The final part of the investigation is of the syn-rift magmatic system responsible for sills and dikes that exploit the normal fault network. These intrusive and extrusive features are important as are potential drilling hazards and can act as baffles to hydrocarbon migration.

scholarly journals Margin-to-Margin Seafloor Spreading in the Eastern Gulf of Aden: A 16 Ma-Long History of Deformation and Magmatism from Seismic Reflection, Gravity and Magnetic Data

2021 ◽  
Vol 9 ◽  
Author(s):  
Morgane Gillard ◽  
Sylvie Leroy ◽  
Mathilde Cannat ◽  
Heather Sloan
Keyword(s):  
Oceanic Crust ◽  
Structural Characteristics ◽  
Seafloor Spreading ◽  
Magnetic Data ◽  
Data Sets ◽  
Gulf Of Aden ◽  
Potential Field Data ◽  
History Of ◽  
Ocean Ridge ◽  
Gravity And Magnetic Data

In this paper we present and analyze spreading-parallel seismic transects that image the oceanic crust in the eastern Gulf of Aden, from the Oman to the Socotra margins, across the active Sheba mid-oceanic ridge and between the Socotra-Hadbeen and Eastern Gulf of Aden Fracture Zones. The correlation of potential field data sets and gravity modelling allow us to document the spreading history of this oceanic basin from the onset of seafloor spreading ∼16 Ma-ago to the present. Two main oceanic sub-domains display distinct structural characteristics associated with different magmatic budgets at this mid-ocean ridge. In addition, we document the occurrence of a magmatic pulse at the Sheba Ridge around 11 Ma leading to the construction of a magmatic plateau in the western part of the studied area. This event led to substantial deformation and additional magmatism in previously formed oceanic crust. It could be related to an off-axis magmatic event previously identified in the adjacent Sheba segment, itself possibly related to the Afar plume.

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