Aeromagnetic regional survey of onshore Australia

Geophysics ◽  
1988 ◽  
Vol 53 (2) ◽  
pp. 254-265
Author(s):  
D. H. Tucker ◽  
I. G. Hone ◽  
D. Downie ◽  
A. Luyendyk ◽  
K. Horsfall ◽  
...  

The Australian Bureau of Mineral Resources (BMR) is responsible for the National Airborne Magnetic Database. This data base consists of results from approximately 3 500 000 line‐km of regional survey flying carried out over 35 years, recording total magnetic intensity. The magnetic data base is one of the most important geophysical data bases for Australia and is used extensively by the minerals and petroleum exploration industries. First‐pass coverage of onshore Australia is aimed for completion in 1992. This coverage contains data from surveys with a wide range of specifications, resulting in a wide range of data quality; some of the areas covered by poorer quality data may be reflown later. For the most part, the intention has been to acquire data at a continuous ground clearance of 150 m and with a line spacing of 1500 m. However, over some sedimentary basins, the line spacing is in excess of 3200 m. New color and grey‐scale (image processed type) digital magnetic maps (pixel maps) are in preparation; these will supersede the 1976 digital magnetic map of Australia, which was gridded on a 1.2 minute mesh (2000 m) mostly by digitizing contours on maps. The new map, produced from flight‐line data, will have a grid size of 0.25 minutes. Initially, a series of maps will be produced with each one covering a block of 4 degrees latitude by 6 degrees longitude, coinciding with standard 1 : 1 000 000 map sheets. An example included for the Adelaide 1 : 1 000 000 map sheet in Southern Australia shows a dramatic increase in the number of anomalies over those that were evident in earlier contour presentations.

1970 ◽  
Vol 10 (1) ◽  
pp. 33
Author(s):  
K. G. Smith

The Basins Study Group is part of the Subsurface Section of the Bureau's Petroleum Exploration Branch and was formed in 1962 to collect and review available basic data on the sedimentary basins of Australia and Papua-New Guinea. The Core and Cuttings Laboratory forms the second part of the Subsurface Section, and the Laboratory's technical staff contribute to basin reviews by carrying out analyses of various kinds, and assist in the collection of data principally by providing thin sections of various sedimentary formations.Recent activities of the Basins Study Group include a review of the Sydney Basin, and an increased effort to assemble basic data on all sedimentary basins, with particular emphasis on the Canning and Carnarvon Basins.The review of the Sydney Basin is nearing completion. It was undertaken with the co-operation of the Geological Survey of New South Wales and received generous support from petroleum exploration companies active in the Basin. The review included detailed petrological examination of twelve wells and selected outcrop samples. The results confirmed the previously-held opinions that the reservoir characteristics of Sydney Basin sediments are generally unfavourable. At present there are no indications of untested onshore areas where an improvement in reservoir properties may occur. The Bureau petrologists detected the rare mineral dawsonite in eight wells; the mineral occurred mostly in Permian sediments, both in marine and non-marine rocks, but it was recorded also from Triassic rocks in the Kurrajong Heights No. 1 well. The review of geophysical data from the Sydney Basin was concentrated mainly on seismic work. The magnetic tapes of three surveys were replayed and considerable improvement in records was effected. Record sections of all seismic surveys were reduced photographically to a horizontal scale of 1:50,000 and the reductions were spliced to provide easily-managed cross-sections. The geophysical review is nearing completion and structure contour maps and isochrons are in preparation.The collection of basic data is done for each sedimentary basin as it becomes available, but present emphasis is on assembling data from Western Australian basins: all seismic traverses in the onshore parts of the Canning and Carnarvon Basins have been plotted at 1:250,000 scale, and with the co-operation of the Geological Survey of Western Australia, bibliographies of the Canning, Carnarvon and Perth Basins have been compiled for issue as Open-file Records. Bibliographies of the Papuan and Ipswich-Clarence Basins have also been compiled.


1977 ◽  
Vol 17 (1) ◽  
pp. 85
Author(s):  
Robert J. Whiteley ◽  
Barry F. Long ◽  
David A. Pratt

The magnetic method is used at many stages of a modern petroleum exploration program. Effective interpretation techniques are required to extract maximum geological information from magnetic data. Those techniques which provide the greatest flexibility and make full use of the talents of experienced interpreters are generally of a semi-automated and interactive nature.There are several practical methods for semi-automated quantitative magnetic interpretation in sedimentary basins. Initial interpretation can be achieved by automatic calculation of characteristic anomaly parameters continuously along original or processed magnetic data profiles. Detailed interpretation of more subtle magnetic features can then follow by theoretical anomaly comparison with field anomalies using interactive portfolio modelling or by direct computation.Examples of the use of these semi-automated techniques in the interpretation of basement and intra-sedimentary magnetic anomalies show that combined magnetic and seismic interpretations can provide considerable insight into the structural processes which have operated in a sedimentary basin.


1999 ◽  
Vol 39 (1) ◽  
pp. 494
Author(s):  
I. Kivior ◽  
D. Boyd

Aeromagnetic surveys have been generally regarded in petroleum exploration as a reconnaissance tool for major structures. They were used commonly in the early stages of exploration to delineate the shape and depth of the sedimentary basin by detecting the strong magnetic contrast between the sediments and the underlying metamorphic basement. Recent developments in the application of computer technology to the study of the earth's magnetic field have significantly extended the scope of aeromagnetic surveys as a tool in the exploration for hydrocarbons. In this paper the two principal methods used in the analysis and interpretation of aeromagnetic data over sedimentary basins are: 1) energy spectral analysis applied to gridded data; and, 2) automatic curve matching applied to profile data. It is important to establish the magnetic character of sedimentary and basement rocks, and to determine the regional magnetic character of the area by applying energy spectral analysis. Application of automatic curve matching to profile data can provide results from the sedimentary section and deeper parts of a basin. High quality magnetic data from an experimental aeromagnetic survey flown over part of the Eromanga/Cooper Basin has recently been interpreted using this new approach. From this survey it is possible to detect major structures such as highs and troughs in the weakly magnetic basement, as well as pick out faults, and magnetic layers in the sedimentary section. The results are consistent with interpretation from seismic and demonstrate that aeromagnetic data can be used to assist seismic interpretation, for example to interpolate between widely spaced seismic lines and sometimes to locate structures which can not be detected from seismic surveys. This new approach to the interpretation of aeromagnetic data can provide a complementary tool for hydrocarbon exploration, which is ideal for logistically difficult terrain and environmentally sensitive areas.


2008 ◽  
Vol 48 (1) ◽  
pp. 359
Author(s):  
Marita Bradshaw

Each year the Australian Government releases new offshore opportunities for petroleum exploration. Thirty-five new exploration areas located across five of Australia’s offshore sedimentary basins are offered in the 2008 Release. All the areas are available through a work program bidding system with closing dates for bids at six and 12 months from the date of release. Acreage in the first round closes on 9 October 2008 and includes the more explored areas. The second closing round on 9 April 2009 comprises acreage located in less well explored and frontier regions. The 2008 exploration areas are in Commonwealth waters offshore of Western Australia and the Northern Territory, and in the Territory of the Ashmore and Cartier Islands adjacent area. The 2008 Release focusses on the North West Shelf, as well as offering two new exploration areas in the Vlaming Sub-basin in the offshore Perth Basin. Seven of the new release areas are located in Australia’s major hydrocarbon producing province, the Carnarvon Basin. They include a shallow water area in the western Barrow Sub-basin and another on the Rankin Platform, three areas in deeper water in the Exmouth Sub-basin and two on the deepwater Exmouth Plateau. Six areas are available for bidding in the Browse Basin and another five in the Bedout Sub-basin of the Roebuck Basin. In the Bonaparte Basin, the 15 Release areas are located in shallow water and represent a range of geological settings, including the Vulcan and Petrel sub-basins, Ashmore Platform and Londonderry High. The 2008 Offshore Petroleum Exploration Release of 35 areas in five basins covers a wide range in size, water depth and exploration maturity to provide investment opportunities suited to both small and large explorers. The Release areas are selected from nominations from industry, the States and Territory, and Geoscience Australia. The focus of the 2008 Release is on the North West Shelf where there is strong industry interest in the producing Carnarvon and Bonaparte basins and in the Browse Basin, the home of super-giant gas fields under active consideration for development. Also included in the 2008 Release is the Bedout Sub-basin, in the Roebuck Basin, located on the central North West Shelf, between the hotly contested Carnarvon and Browse basins. In addition, the Release show-cases the southern Vlaming Sub-basin, Perth Basin, where recent studies by Geoscience Australia provide a new understanding of petroleum potential (Nicholson et al, this volume).


Minerals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1041
Author(s):  
Ning Lu ◽  
Guixiang Liao ◽  
Yongzai Xi ◽  
Hongshan Zheng ◽  
Fang Ben ◽  
...  

With the increasing demand for mineral resources, there is an inevitable trend to carry out deep prospecting in existing old mines to find a second or even third mining space. Deep prospecting is also an affordable and practical way to prolong the lives of mines and provide a sustainable supply of mineral resources. The magnetic survey is arguably the most effective method for iron ore prospecting. In this paper, a high resolution airborne magnetic (HRAM) survey for deep iron prospecting in the Jinling iron ore cluster (JIOC) was carried out in 2018, which renewed the field magnetic data of the JIOC obtained in the 1980s. From previous studies, almost all iron deposits in the JIOC are spatially distributed in the contact zone between the intrusive rocks and the surrounding rocks. The key prospecting areas were inferred by delineating intrusive rock boundaries via boundary enhancement and edge detection methods, and one of the areas was verified by drilling.


2018 ◽  
Vol 58 (2) ◽  
pp. 821
Author(s):  
Irena Kivior ◽  
Stephen Markham ◽  
Leslie Mellon ◽  
David Boyd

Volcanic layers within sedimentary basins cause significant problems for petroleum exploration because the attenuation of the seismic signal masks the underlying geology. A test study was conducted for the South Australia Government to map the thickness of volcanics and sub-volcanic geology over a large area in the Gawler Range Volcanics province. The area is covered by good quality magnetic data. The thickness of volcanics and basement configuration was unknown as there has only been a limited amount of drilling. The Automatic Curve Matching (ACM) method was applied to located magnetic data and detected magnetic sources within different rock units, providing their depth, location, geometry and magnetic susceptibility. The magnetic susceptibilities detected by ACM allowed the differentiation of the volcanics and the underlying basement. The base of volcanics and the depth to the top of basement was mapped along 75 km NS profiles, that were spaced 1 km apart over a distance of 220 km. The volcanic and basement magnetic susceptibilities and the magnetic source distribution pattern were used as key determinants to interpret the depth to the two interfaces. The results for each interface were gridded, and images of the base of volcanics and depth to basement were generated. The mapped volcanics thickness was validated by comparison with the results from drilling, with the volcanics thickness matching very well. After project completion, a passive seismic survey was conducted in part of the test area, indicating a base of volcanics of ~4 km, which further confirmed the results.


Geophysics ◽  
1976 ◽  
Vol 41 (6) ◽  
pp. 1337-1345 ◽  
Author(s):  
A. R. Fraser ◽  
F. J. Moss ◽  
A. Turpie

The Australian Bureau of Mineral Resources, Geology and Geophysics, completed a 15 year systematic reconnaissance gravity survey of Australia in 1974. Using helicopters, gravity stations were established at 11 km spacing over most of the continent, and at 7 km spacing in South Australia and Tasmania. Station elevations were measured barometrically and station positions were marked on aerial photographs and transferred to 1:250,000 photocenter base maps. Gravity and elevation controls were maintained by ties to specially established control networks. A Bouguer anomaly map of Australia has been compiled from the reconnaissance data, and from information from other gravity surveys by state governments, petroleum exploration companies, and academic institutions which together cover about 15 percent of the total area. The compilation uses a total of about 170,000 gravity observations. The accuracy of Bouguer anomaly values, taking account of errors in the gravity, elevation, and position measurements, is estimated to be better than ± 2.0 mgal. The Bouguer anomaly fields over Australia are divided into nine regional gravity divisions, in each of which the gravity contour pattern has some degree of uniformity, or is such as to imply tectonic affinities between the sources of individual gravity features. The gravity divisions can be correlated with various metamorphic complexes and orogenic provinces, ranging in age from Archaean to Paleozoic, which also form the basements to extensive sedimentary platform covers. The reconnaissance gravity results have been made public as the survey has progressed to assist in regional geologic studies and the search for petroleum and minerals. They have proved to be of considerable benefit in delineating regional structures and in providing leads for more detailed geophysical investigations. Predictions of the structures of sedimentary basins have been made and possible extensions to mineral provinces have been indicated. The results have also been used in deep crustal and upper mantle studies and in geodesy.


Author(s):  
Jesper Kresten Nielsen ◽  
Nils-Martin Hanken

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Kresten Nielsen, J., & Hanken, N.-M. (2002). Late Permian carbonate concretions in the marine siliciclastic sediments of the Ravnefjeld Formation, East Greenland. Geology of Greenland Survey Bulletin, 191, 126-132. https://doi.org/10.34194/ggub.v191.5140 _______________ This investigation of carbonate concretions from the Late Permian Ravnefjeld Formation in East Greenland forms part of the multi-disciplinary research project Resources of the sedimentary basins of North and East Greenland (TUPOLAR; Stemmerik et al. 1996, 1999). The TUPOLAR project focuses on investigations and evaluation of potential hydrocarbon and mineral resources of the Upper Permian – Mesozoic sedimentary basins. In this context, the Upper Permian Ravnefjeld Formation occupies a pivotal position because it contains local mineralisations and has source rock potential for hydrocarbons adjacent to potential carbonate reservoir rocks of the partly time-equivalent Wegener Halvø Formation (Harpøth et al. 1986; Surlyk et al. 1986; Stemmerik et al. 1998; Pedersen & Stendal 2000). A better understanding of the sedimentary facies and diagenesis of the Ravnefjeld Formation is therefore crucial for an evaluation of the economic potential of East Greenland.


2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Takao Koyama ◽  
Wataru Kanda ◽  
Mitsuru Utsugi ◽  
Takayuki Kaneko ◽  
Takao Ohminato ◽  
...  

AbstractKusatsu-Shirane volcano is one of the active volcanoes in Japan. Phreatic explosions occurred in Mt. Shirane in 1983 and most recently, in 2018, in Mt. Motoshirane. Information on the subsurface structure is crucial for understanding the activity of volcanoes with well-developed hydrothermal systems where phreatic eruptions occur. Here, we report aeromagnetic surveys conducted at low altitudes using an unmanned helicopter. The survey aimed to obtain magnetic data at a high spatial resolution to map the magnetic anomaly and infer the magnetization intensity distribution in the region immediately after the 2018 Mt. Motoshirane eruption. The helicopter used in the survey was YAMAHA FAZER R G2, an autonomously driven model which can fly along a precisely programmed course. The flight height above the ground and a measurement line spacing were set to ~ 150 m and ~ 100 m, respectively, and the total flight distance was 191 km. The measured geomagnetic total intensity was found to vary by ~ 1000 nT peak-to-peak. The estimated magnetization intensity derived from measured data showed a 100 m thick magnetized surface layer with normal polarity, composed of volcanic deposits of recent activities. Underneath, a reverse-polarity magnetization was found, probably corresponding to the Takai lava flow in the Early Quaternary period (~ 1 Ma) mapped in the region. Our results demonstrate the cost-effectiveness and accuracy of using drone magnetometers for mapping the rugged terrain of volcanoes.


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