Geological Mapping Capabilities of the QUESTEM Airborne Electromagnetic System for Mineral Exploration — Mt. Isa Inlier, Queensland

Abstract. Reprocessing of regional-scale airborne electromagnetic data is used to build a 3D geological model of the Nasia sub-basin, northern Ghana. The resulting 3D geological model consistently integrates all the prior pieces of information brought by electromagnetic data, lithologic logs, ground-based geophysical surveys, and geological knowledge of the terrain. The geo-modeling process is aimed at defining the lithostratigraphy of the area, chiefly to improve the stratigraphic definition of the area, and for hydrogeological purposes. The airborne electromagnetic measurements, consisting of GEOTEM B-field data, were originally collected for mineral exploration purposes. Thus, those B-field data had to be (re)processed and properly inverted as the original survey and data handling were designed for the detection of potential mineral targets and not for detailed geological mapping. These new geophysical inversion results, compared with the original conductivity–depth images, provided a significantly different picture of the subsurface. The new geophysical model led to new interpretations of the geological settings and to the construction of a comprehensive 3D geo-model of the basin. In this respect, the evidence of a hitherto unexposed system of paleovalleys could be inferred from the airborne data. The stratigraphic position of these paleovalleys suggests a distinctly different glaciation history from the known Marinoan events, commonly associated with the Kodjari formation of the Voltaian sedimentary basin. Indeed, the presence of the paleovalleys within the Panabako may be correlated with mountain glaciation within the Sturtian age, though no unequivocal glaciogenic strata have yet been identified. Pre-Marinoan glaciation is recorded in rocks of the Wassangara group of the Taoudéni Basin. The combination of the Marinoan and, possibly, Sturtian glaciation episodes, both of the Cryogenian period, can be an indication of a Neoproterozoic Snowball Earth. Hence, the occurrence of those geological features not only has important socioeconomic consequences – as the paleovalleys can act as reservoirs for groundwater – but also from a scientific point of view, they could be extremely relevant as their presence would require a revision of the present stratigraphy of the area.

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New regional stratigraphic insights from a 3D geological model of the Nasia Sub-basin, Ghana, developed for hydrogeological purposes and based on reprocessed B-field data, originally collected for mineral exploration

10.5194/se-2019-145 ◽

2019 ◽

Author(s):

Elikplim Abla Dzikunoo ◽

Giulio Vignoli ◽

Flemming Jørgensen ◽

Sandow Mark Yidana ◽

Bruce Banoeng-Yakubo

Keyword(s):

Field Data ◽

Mineral Exploration ◽

Regional Scale ◽

Geological Mapping ◽

Northern Ghana ◽

Geological Model ◽

Electromagnetic Data ◽

3D Geological Model ◽

Geophysical Surveys ◽

Airborne Electromagnetic

Abstract. Re-processing of regional-scale airborne electromagnetic data is used in building a 3D geological model of the Nasia Sub-Basin, Northern Ghana. The resulting 3D geological model consistently integrates all the pieces of information brought by the electromagnetic data, lithologic logs, ground-based geophysical surveys and the prior geological knowledge of the terrain based on previous research. The geo-modelling process is aimed at defining the lithostratigraphy of the area, chiefly to improve the stratigraphic definition of the area as well as for hydrogeological purposes. The airborne electromagnetic measurements, consisting of GEOTEM B-field data, were originally collected for mineral exploration purposes. Thus, those B-field data had to be (re)processed and properly inverted as the original survey and data handling were designed for the detection of potential mineral targets and not for detailed geological mapping. These new geophysical inversion results, compared with the original Conductivity Depth Images, provided a significantly different picture of the subsurface. The new geophysical model led to new interpretations of the geological settings and to the construction of a comprehensive 3D geomodel of the basin. In this respect, the evidences of a hitherto unexposed paleovalley could be inferred from the airborne data. The stratigraphic position of these paleovalleys suggests a distinctly different glaciation history from the Marinoan events, commonly associated with the Kodjari formation of the Voltaian sedimentary basin. Indeed, their presence may be correlated to mountain glaciation within the Sturtian period though no unequivocal glaciogenic strata have yet been identified. This pre-Marinoan glaciation is recorded in rocks of the Wassangara group of the Taoudeni basin. The combination of the Marinoan and, possibly, Sturtian glaciation episodes, both of the Cryogenian period, can be an indication of a Neoproterozoic Snowball Earth. Hence, the occurrence of those geological features, do not only have an important socio-economic consequences – as the paleovalleys can act as reservoirs for groundwater – but, also from a scientific point of view, could be extremely relevant – as their presence would require a revision of the present stratigraphy of the area.

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Airborne geophysical surveys in Greenland – 1996 update

Geological Survey of Denmark and Greenland Bulletin ◽

10.34194/ggub.v176.5069 ◽

1997 ◽

pp. 75-79

Author(s):

Robert W. Stemp

Keyword(s):

Mineral Exploration ◽

Geological Mapping ◽

Digital Data ◽

Magnetic Survey ◽

Aeromagnetic Survey ◽

West Greenland ◽

South West ◽

Geophysical Surveys ◽

The Government ◽

Airborne Geophysical Data

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Stemp, R. W. (1997). Airborne geophysical surveys in Greenland – 1996 update. Geology of Greenland Survey Bulletin, 176, 75-79. https://doi.org/10.34194/ggub.v176.5069 _______________ Two major airborne geophysical surveys were carried out in 1996, the third year of a planned five-year electromagnetic and magnetic survey programme (project AEM Greenland 1994–1998) financed by the Government of Greenland, and the second year of an aeromagnetic survey programme (project Aeromag) jointly financed by the governments of Denmark and Greenland; both projects are managed by the Geological Survey of Denmark and Greenland (GEUS). The two 1996 surveys were: 1) Project Aeromag 1996 in South-West and southern West Greenland;2) Project AEM Greenland 1996 in South-West Greenland. All areas surveyed and planned for future surveys as of March 1997 are shown in Figure 1. Results of both the 1996 surveys were released in March 1997, as a continuation of a major effort to make high quality airborne geophysical data available for both mineral exploration and geological mapping purposes. The data acquired are included in geoscientific databases at GEUS for public use; digital data and maps may be purchased from the Survey. The main results from the 1996 surveys are described in Thorning & Stemp (1997) and Stemp (1997). Two further new airborne surveys have already been approved for data acquisition during the 1997 field season, with subsequent data release in March 1998. A summary of all surveys completed, in progress or planned since the formal inception of project AEM Greenland 1994–1998 is given in Table 1. The programme was expanded to include a separate regional aeromagnetic survey in 1995, provisionally for 1995–1996, with extension subject to annual confirmation and funding.

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Application of Remote Sensing Techniques in Geological Mapping and Mineral Exploration - A Case Study from Dharwar Craton

Journal of the Geological Society of India ◽

10.1007/s12594-022-1943-z ◽

2022 ◽

Vol 98 (1) ◽

pp. 144-145

Author(s):

Nisha Rani

Keyword(s):

Remote Sensing ◽

Mineral Exploration ◽

Dharwar Craton ◽

Geological Mapping ◽

Remote Sensing Techniques

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Observations of the Earth’s resources

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1969.0004 ◽

1969 ◽

Vol 308 (1493) ◽

pp. 173-182 ◽

Cited By ~ 1

Keyword(s):

Mineral Exploration ◽

Geological Mapping ◽

The Other ◽

Ground Control ◽

Great Contribution ◽

Know How ◽

Control Information ◽

The World ◽

The One ◽

Effective Development

In attempting to present some observations on the kind of information on the Earth’s resources which may be obtained from spacecraft and space satellites, I think I should explain that I speak as a geographer with research interests in the field of biogeography/geobotany where I have been concerned with the use of vegetation in mineral exploration work and in the assessment of land potential for agricultural and other uses. In the course of this work I have come to appreciate major problems of regional or even continental dimensions and have become aware of the great potential offered by suitably equipped Earth resources satellites for providing information which would assist their solution. At the same time I have come to recognize the great contribution which Earth resources satellites can make in the fields of agriculture, forestry and conservation, topographical and geological mapping, hydrology, oceanography, land use and urban planning, to mention but a few. As a setting for my subsequent remarks I would like to state what I believe to be the relative positions of the U. S. A. and the U. S. S. R. on the one hand and this country and certain West European countries on the other with regard to the acquisition of information from Earth resources satellites. America and Russia have led the world in space research. They have the resources, the facilities and the technical know-how for placing spacecraft and satellites in orbit. For the effective development of Earth resources satellites, however, ground control information is essential. Here this country, together with member and former member countries of the Commonwealth possesses a body of people scattered through universities, government departments and organizations, commerce and industry whose firsthand knowledge of remote terrain in many parts of the world is unrivalled. This knowledge harnessed into an Earth resources satellites programme could enable this country to make a leading contribution to the development of the less developed parts of the world and at the same time materially assist the economy of this country.

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Systematic survey of K, Th, and U signatures in airborne radiometric data from Australian meteorite impact structures: Possible causes of circular features and implications

Large Meteorite Impacts and Planetary Evolution VI ◽

10.1130/2021.2550(15) ◽

2021 ◽

Author(s):

Cheikh Ahmadou Bamba Niang ◽

David Baratoux ◽

Dina Pathé Diallo ◽

Pierre Rochette ◽

Mark W. Jessell ◽

...

Keyword(s):

Case Studies ◽

Crustal Deformation ◽

Seismic Reflection ◽

Gamma Ray ◽

Mineral Exploration ◽

Geological Mapping ◽

Impact Event ◽

Systematic Survey ◽

The Impact ◽

Radiometric Data

ABSTRACT Airborne radiometric (gamma-ray) data provide estimates of the concentrations of potassium (K), thorium (Th), and uranium (U) in soil, regolith, and bedrock. Radiometric data constitute an important source of geochemical information, commonly used in mineral exploration and for geological mapping of Earth and other planets. Airborne radiometric data have rarely been applied to the exploration and analyses of impact structures, in contrast with other conventional geophysical tools (e.g., gravimetry, magnetism, and seismic reflection/refraction). This work represents the first systematic survey of the K, Th, and U radiometric signatures of Australian impact structures, based on the continent-wide airborne radiometric coverage of Australia. We first formulated several hypotheses regarding the possible causes of formation of circular radiometric patterns associated with impact structures. Then, the radiometric signatures of 17 exposed impact structures in Australia were documented. Our observations confirmed the supposition that impact structures are commonly associated with circular radiometric patterns. We then selected the five structures with the most prominent circular radiometric patterns (Gosses Bluff, Lawn Hill, Acraman, Spider, and Shoemaker), and we discuss the possible origin of these anomalies. Based on these five case studies, we argue that such patterns result from either crustal deformation induced by the impact event and/or from postimpact superficial processes controlled by the crater topography. This work also suggests that airborne radiometric data may be useful, in combination with other geophysical tools, in the search for new possible impact structures.

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Development And Evaluation Of A Second-Generation Airborne Electromagnetic System For Detection Of Unexploded Ordnance

10.3997/2214-4609-pdb.191.11uxo8 ◽

2002 ◽

Author(s):

William E. Doll ◽

T. Jeffrey Gamey ◽

Les P. Beard ◽

David T. Bell ◽

J.S. Holladay ◽

...

Keyword(s):

Second Generation ◽

Unexploded Ordnance ◽

Electromagnetic System ◽

Airborne Electromagnetic

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The aeromagnetic survey program of the Geological Survey of Canada: contribution to regional geological mapping and mineral exploration

Canadian Journal of Earth Sciences ◽

10.1139/e93-021 ◽

1993 ◽

Vol 30 (2) ◽

pp. 243-260 ◽

Cited By ~ 11

Author(s):

D. J. Teskey ◽

P. J. Hood ◽

L. W. Morley ◽

R. A. Gibb ◽

P. Sawatzky ◽

...

Keyword(s):

Mineral Exploration ◽

National Research Council ◽

High Sensitivity ◽

Geological Mapping ◽

Geological Survey ◽

The Arctic ◽

Navigation Systems ◽

Current Standard ◽

Private Industry ◽

Aeromagnetic Survey

The aeromagnetic survey operations of the Geological Survey of Canada (GSC) began in 1946, utilizing a magnetometer in a bird system towed by a Royal Canadian Air Force Anson. Subsequent early operations were carried out by the GSC-operated Canso and Aero Commander aircraft. In 1961, the GSC in-house survey team formed the nucleus of a contract surveys group set up to monitor a new program established to complete the aeromagnetic mapping of the Canadian Shield in 12 years on a cost-sharing basis with the provinces. Today, surveys are carried out under contract by light twin-engine aircraft such as the Cessna 404 and even, in some cases, single-engine aircraft that utilize compact computer-controlled data acquisition and navigation systems and inboard magnetometer installations. Early systems were capable of resolution of only a few nanoteslas (nT) compared to the current standard of 0.1 nT or less, and flight path positioning with 35 mm film and photomosaics or topographical maps was extremely challenging. Despite these limitations, the careful selection of survey parameters and attention given to quality control have resulted in a world-class aeromagnetic data base that has contributed significantly to regional geological mapping and to mineral and oil exploration in Canada. Concurrently, the GSC carried out research programs into the development of instrumentation and into processing, interpretation, and enhancement techniques. In 1968, the GSC acquired its own platform, a Beechcraft B80 Queenair, which was used to develop high-sensitivity techniques, and an inboard gradiometer system, which was transferred to private industry in 1983. The GSC, in cooperation with the Flight Research Laboratory of the National Research Council of Canada, has also conducted a program of research into magnetometry and navigation combined with aeromagnetic studies of the Arctic since 1962.

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