Airborne geophysical surveys in Greenland in 1998

1999 ◽  
pp. 34-38 ◽  
Author(s):  
Thorkild M. Rasmussen ◽  
Leif Thorning
Keyword(s):  
High Resolution ◽  
Geophysical Data ◽  
Digital Data ◽  
Geological Survey ◽  
Magnetic Data ◽  
Magnetic Survey ◽  
Original Series ◽  
Geophysical Surveys ◽  
The Government

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Rasmussen, T. M., & Thorning, L. (1999). Airborne geophysical surveys in Greenland in 1998. Geology of Greenland Survey Bulletin, 183, 34-38. https://doi.org/10.34194/ggub.v183.5202 _______________ Airborne geophysical surveying in Greenland during 1998 consisted of a magnetic project referred to as ‘Aeromag 1998’ and a combined electromagnetic and magnetic project referred to as ‘AEM Greenland 1998’. The Government of Greenland financed both with administration managed by the Geological Survey of Denmark and Greenland (GEUS). With the completion of the two projects, approximately 305 000 line km of regional high-resolution magnetic data and approximately 75 000 line km of detailed multiparameter data (electromagnetic, magnetic and partly radiometric) are now available from government financed projects. Figure 1 shows the location of the surveyed areas with highresolution geophysical data together with the area selected for a magnetic survey in 1999. Completion of the two projects was marked by the release of data on 1 March, 1999. The data are included in the geoscientific databases at the Survey for public use; digital data and maps may be purchased from the Survey.

Aeromagnetic survey in southern West Greenland: project Aeromag 1999

2000 ◽  
pp. 73-77 ◽  
Author(s):  
Thorkild M. Rasmussen ◽  
Jeroen A.M. Van Gool
Keyword(s):  
European Union ◽  
Measured Data ◽  
Geophysical Data ◽  
Geological Survey ◽  
Aeromagnetic Survey ◽  
Original Series ◽  
West Greenland ◽  
The Government ◽  
Airborne Geophysical Data ◽  
Surface Geology

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Rasmussen, T. M., & van Gool, J. A. (2000). Aeromagnetic survey in southern West Greenland: project Aeromag 1999. Geology of Greenland Survey Bulletin, 186, 73-77. https://doi.org/10.34194/ggub.v186.5218 _______________ The acquisition of public airborne geophysical data from Greenland that commenced in 1992 continued in 1999 with project Aeromag 1999, an aeromagnetic survey of part of southern West Greenland. This paper presents results of the aeromagnetic survey and discusses the correlation of the measured data with the previously mapped surface geology. The project was financed by the Government of Greenland and managed by the Geological Survey of Denmark and Greenland. Sander Geophysics Ltd., Ottawa, Canada, was selected in April 1999 as the contractor for the project through a European Union opentender procedure.

Airborne geophysical surveys in Greenland – 1996 update

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.

Aeromagnetic survey in central West Greenland: project Aeromag 2001

2002 ◽  
pp. 67-72 ◽  
Author(s):  
Thorkild M. Rasmussen
Keyword(s):  
High Resolution ◽  
Magnetic Measurements ◽  
Geophysical Data ◽  
High Quality ◽  
Aeromagnetic Survey ◽  
Original Series ◽  
West Greenland ◽  
Airborne Measurements ◽  
Geophysical Surveys ◽  
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. Rasmussen, T. M. (1). Aeromagnetic survey in central West Greenland: project Aeromag 2001. Geology of Greenland Survey Bulletin, 191, 67-72. https://doi.org/10.34194/ggub.v191.5130 The series of government-funded geophysical surveys in Greenland was continued during the spring and summer of 2001 with a regional aeromagnetic survey north of Uummannaq, project Aeromag 2001 (Fig. 1). The survey added about 70 000 line kilometres of high-quality magnetic measurements to the existing database of modern airborne geophysical data from Greenland. This database includes both regional high-resolution aeromagnetic surveys and detailed surveys with combined electromagnetic and magnetic airborne measurements.

Airborne geophysical surveys in central West Greenland and central East Greenland in 1997

1998 ◽  
pp. 63-66
Author(s):  
Leif Thorning ◽  
Robert W. Stemp
Keyword(s):  
Digital Data ◽  
Magnetic Survey ◽  
The European Union ◽  
Aeromagnetic Survey ◽  
East Greenland ◽  
West Greenland ◽  
Transient Electromagnetic ◽  
Geophysical Surveys ◽  
The Government ◽  
North Greenland

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Thorning, L., & Stemp, R. W. (1998). Airborne geophysical surveys in central West Greenland and central East Greenland in 1997. Geology of Greenland Survey Bulletin, 180, 63-66. https://doi.org/10.34194/ggub.v180.5087 _______________ In order to stimulate mining exploration activity in Greenland the Government of Greenland decided in 1993 to finance a five-year programme of airborne electromagnetic surveys over selected regions of Greenland, Project AEM Greenland 1994–1998. By the end of 1996 three surveys had been undertaken in various parts of Greenland (Stemp & Thorning 1995a, b; Stemp 1996a, b; Stemp 1997a, b). In 1992 the Danish Government financed a small aeromagnetic survey (Project Aeromag 1992; Thorning 1993). Regional aeromagnetic surveying was taken up again when the governments of Denmark and Greenland jointly financed two aeromagnetic surveys in 1995 and 1996 – the projects Aeromag 1995 and Aeromag 1996 (Thorning & Stemp 1997). To this suite of airborne geophysical surveys of selected regions in Greenland were added two surveys in 1997, both financed by the Government of Greenland. The fourth year of Project AEM Greenland 1994–1998 encompassed a transient electromagnetic (GEOTEM) and magnetic survey over northern Jameson Land, central East Greenland, while Project Aeromag 97 added a regional aeromagnetic survey over Disko Bugt – Nuussuaq, central West Greenland. As in previous years, commercial geophysical contractors carried out the survey operations in Greenland according to an agreement with the Geological Survey of Denmark and Greenland (GEUS) entered into after international tendering following rules of the European Union. GEUS manages the projects and organises the distribution and use of the results. The new maps and digital data from the two 1997 surveys, a total of 85 252 line kilometres of data covering 51 414 km2, were released to the public on 1 March 1998. This note provides some introductory information about the two surveys. Further information can be found in reports by Stemp (1998) and Thorning (in press); both include a number of full-page colour anomaly maps from the survey areas. The airborne geophysical programme will continue in 1998, and the areas to be surveyed have already been selected. The final year of Project AEM Greenland 1994–1998 will include combined GEOTEM and magnetic surveys over two regions in North Greenland: Washington Land in western North Greenland, where operations are expected to start in May 1998 operating out of Alert in Canada, and later in the season over J.C. Christensen Land in central North Greenland operating out of Station Nord in eastern North Greenland. Project Aeromag 1998 will continue the regional aeromagnetic survey programme in West Greenland, extending the coverage by including most of the region from 63°45′N to 66°N in southern West Greenland. This project will be based at Nuuk and start in March 1998. The Government of Greenland will finance all surveys in 1998. Figure 1 shows all survey areas for the electromagnetic and magnetic surveys of Project AEM Greenland 1994–1998 and the aeromagnetic survey areas of Project Aeromag 1992, 1995, 1996, 1997 and 1998.

Petroleum geological activities in West Greenland in 1998

1999 ◽  
pp. 46-56
Author(s):  
Flemming G. Christiansen ◽  
Anders Boesen ◽  
Jørgen A. Bojesen-Koefoed ◽  
James A. Chalmers ◽  
Finn Dalhoff ◽  
...  
Keyword(s):  
Seismic Data ◽  
Working Group ◽  
Petroleum Exploration ◽  
Geological Survey ◽  
Original Series ◽  
West Greenland ◽  
Phillips Petroleum ◽  
Petroleum Resources ◽  
The Government ◽  
Year 2000

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Christiansen, F. G., Boesen, A., Bojesen-Koefoed, J. A., Chalmers, J. A., Dalhoff, F., Dam, G., Ferré Hjortkjær, B., Kristensen, L., Melchior Larsen, L., Marcussen, C., Mathiesen, A., Nøhr-Hansen, H., Pedersen, A. K., Pedersen, G. K., Pulvertaft, T. C. R., Skaarup, N., & Sønderholm, M. (1999). Petroleum geological activities in West Greenland in 1998. Geology of Greenland Survey Bulletin, 183, 46-56. https://doi.org/10.34194/ggub.v183.5204 _______________ In the last few years there has been renewed interest for petroleum exploration in West Greenland and licences have been granted to two groups of companies: the Fylla licence operated by Statoil was awarded late in 1996; the Sisimiut-West licence operated by Phillips Petroleum was awarded in the summer of 1998 (Fig. 1). The first offshore well for more than 20 years will be drilled in the year 2000 on one of the very spectacular structures within the Fylla area. To stimulate further petroleum exploration around Greenland – and in particular in West Greenland – a new licensing policy has been adopted. In July 1998, the administration of mineral and petroleum resources was transferred from the Danish Ministry of Environment and Energy to the Bureau of Minerals and Petroleum under the Government of Greenland in Nuuk. Shortly after this, the Greenlandic and Danish governments decided to develop a new exploration strategy. A working group consisting of members from the authorities (including the Geological Survey of Denmark and Greenland – GEUS) made recommendations on the best ways to stimulate exploration in the various regions on- and offshore Greenland. The strategy work included discussions with seismic companies because it was considered important that industry acquires additional seismic data in the seasons 1999 and 2000.

scholarly journals Petrophysically and geologically guided multi-physics inversion using a dynamic Gaussian mixture model

2020 ◽  
Vol 224 (1) ◽  
pp. 40-68 ◽  
Author(s):  
Thibaut Astic ◽  
Lindsey J Heagy ◽  
Douglas W Oldenburg
Keyword(s):  
Gaussian Mixture Model ◽  
Mixture Model ◽  
Gaussian Mixture ◽  
Quantitative Information ◽  
Geophysical Data ◽  
Magnetic Data ◽  
Data Sets ◽  
Data Set ◽  
Geophysical Surveys ◽  
Geological Information

SUMMARY In a previous paper, we introduced a framework for carrying out petrophysically and geologically guided geophysical inversions. In that framework, petrophysical and geological information is modelled with a Gaussian mixture model (GMM). In the inversion, the GMM serves as a prior for the geophysical model. The formulation and applications were confined to problems in which a single physical property model was sought, and a single geophysical data set was available. In this paper, we extend that framework to jointly invert multiple geophysical data sets that depend on multiple physical properties. The petrophysical and geological information is used to couple geophysical surveys that, otherwise, rely on independent physics. This requires advancements in two areas. First, an extension from a univariate to a multivariate analysis of the petrophysical data, and their inclusion within the inverse problem, is necessary. Secondly, we address the practical issues of simultaneously inverting data from multiple surveys and finding a solution that acceptably reproduces each one, along with the petrophysical and geological information. To illustrate the efficacy of our approach and the advantages of carrying out multi-physics inversions coupled with petrophysical and geological information, we invert synthetic gravity and magnetic data associated with a kimberlite deposit. The kimberlite pipe contains two distinct facies embedded in a host rock. Inverting the data sets individually, even with petrophysical information, leads to a binary geological model: background or undetermined kimberlite. A multi-physics inversion, with petrophysical information, differentiates between the two main kimberlite facies of the pipe. Through this example, we also highlight the capabilities of our framework to work with interpretive geological assumptions when minimal quantitative information is available. In those cases, the dynamic updates of the GMM allow us to perform multi-physics inversions by learning a petrophysical model.

Acquisition of high-resolution multichannel seismic data in the offshore part of the Nuussuaq Basin, central West Greenland

2001 ◽  
pp. 34-40
Author(s):  
Christian Marcussen ◽  
James A. Chalmers ◽  
Holger Lykke Andersen ◽  
Rasmus Rasmussen ◽  
Trine Dahl-Jensen
Keyword(s):  
High Resolution ◽  
Seismic Data ◽  
Research Programme ◽  
Geological Survey ◽  
Seismic Survey ◽  
Energy Research ◽  
Original Series ◽  
West Greenland ◽  
Geological Institute ◽  
Multichannel Seismic 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: Marcussen, C., Chalmers, J. A., Lykke Andersen, H., Rasmussen, R., & Dahl-Jensen, T. (2001). Acquisition of high-resolution multichannel seismic data in the offshore part of the Nuussuaq Basin, central West Greenland. Geology of Greenland Survey Bulletin, 189, 34-40. https://doi.org/10.34194/ggub.v189.5195 _______________ A high-resolution multichannel seismic survey (project NuussuaqSeis 2000) was carried out from 18 July to 2 August 2000 in the offshore part of the Nuussuaq Basin, central West Greenland using the Danish research vessel R/V Dana with seismic equipment from the Geological Institute, Aarhus University, Denmark. Funding for the project was provided by the Danish Energy Research Programme, the Bureau of Minerals and Petroleum, Nuuk, Greenland, the Geological Institute of Aarhus University and the Geological Survey of Denmark and Greenland (GEUS). After completion of the NuussuaqSeis 2000 project, R/V Dana was used for a three-day coring project in Disko Bugt (see Kuijpers et al. 2001, this volume) before the ship returned to Denmark.

Next Generation High-Definition Geomagnetic Model for Wellbore Positioning, Incorporating New Crustal Magnetic Data

2021 ◽  
Author(s):  
Manoj Nair ◽  
Arnaud Chulliat ◽  
Adam Woods ◽  
Patrick Alken ◽  
Brian Meyer ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Resolution ◽  
Error Model ◽  
Magnetic Data ◽  
Magnetic Observatory ◽  
Magnetic Survey ◽  
High Definition ◽  
The Core ◽  
Ground Magnetic ◽  
The Magnetic Field

Abstract Magnetic wellbore positioning depends on an accurate representation of the Earth's magnetic field,where the borehole azimuth is inferred by comparing the magnetic field measured-whiledrilling (MWD) with a geomagnetic reference model. Therefore, model accuracy improvements reduce the position uncertainties. An improved high-resolution model describing the core, crustal and external components of the magnetic field is presented, and it is validated with anindependent set of measurements. Additionally, we benchmark it against other high-resolution geomagnetic models. The crustal part of the improved high-definition model is based on NOAA/NCEI's latest magnetic survey compilation "EMAG2v3" which includes over 50 millionnew observations in several parts of the world, including the Gulf of Mexico and Antarctica, and does not rely on any prior information from sea-floor geology, unlike earlier versions. The core field part of the model covers years 1900 through 2020 andis inferred from polar-orbiting satellite data as well as ground magnetic observatory data. The external field part is modelled to degree and order 1 for years 2000 through 2020. The new model has internal coefficients to spherical harmonic degree and order 790, resolving magnetic anomalies to approximately 51 km wavelength at the equator. In order to quantitatively assess its accuracy, the model was compared with independent shipborne, airborne and ground magnetic measurements. We find that the newmodel has comparable or smaller errors than the other models benchmarkedagainst it over the regions of comparisons. Additionally, we compare theimproved model against magnetic datacollected from MWD; the residual error lies well within the accepted industry error model, which may lead tofuture error model improvements.

GEOPHYSICAL SURVEY OF THE ARKANSAS BAUXITE REGION

Geophysics ◽  
1944 ◽  
Vol 9 (3) ◽  
pp. 324-366 ◽  
Author(s):  
Mark C. Malamphy ◽  
James L. Vallely
Keyword(s):  
Hot Spring ◽  
Geophysical Survey ◽  
Geophysical Data ◽  
Magnetic Survey ◽  
Large Area ◽  
Clark County ◽  
Ore Bodies ◽  
Geophysical Surveys ◽  
Bauxite Ore ◽  
Geophysical Anomalies

Magnetic and gravimetric surveys were conducted over an area of approximately 1400 square miles in the bauxite district of central Arkansas. The primary purpose of these surveys was to discover any possible buried and hitherto unknown syenite masses favorable for the occurrence of bauxite and to determine the approximate position of the buried flanks of the known syenite masses which might offer conditions favorable for the discovery of new ore bodies. These surveys indicated that the various syenite outcrops are domes or bosses on a large batholith and that other similar domes occur on the batholith but do not outcrop. Drilling on the local geophysical anomalies proved the presence of 10 buried domes, but only 2 were found to project above the upper surface of the Midway clays, a requisite of conditions favorable for the occurrence of bauxite ore bodies. The geophysical data indicated the approximate configuration of the buried flanks of the known syenite outcrops, and the portions of these flanks that project above the Midway have now been outlined more accurately by drilling. The geophysical surveys have produced evidence permitting the elimination of a large area as unfavorable for the occurrence of bauxite. Magnetic surveys extending along the Midway‐Wilcox contact from Gurdon in Clark County on the southwest to Searcy in White County on the northeast have proved the improbability of the existence of other syenite masses similar to those found in Pulaski and Saline Counties. A detailed magnetic survey of the Magnet Cove area in Hot Spring County has proved that the syenite mass exposed in that locality is an isolated intrusion and entirely unrelated to those of Pulaski and Saline Counties. This syenite mass does not occur under conditions believed to be favorable for the occurrence of bauxite.

A review of Greenland activities, 1997

1998 ◽  
pp. 7-9
Author(s):  
Martin Ghisler
Keyword(s):  
Mineral Exploration ◽  
Field Work ◽  
Geophysical Data ◽  
Geological Survey ◽  
Original Series ◽  
Wide Range ◽  
Scientific Papers ◽  
Offshore Field

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Ghisler, M. (1998). A review of Greenland activities, 1997. Geology of Greenland Survey Bulletin, 180, 7-9. https://doi.org/10.34194/ggub.v180.5078 _______________ This is the second volume of Review of Greenland activities. It follows the tradition of Report of activities of the former Geological Survey of Greenland that was issued for 30 years until 1996.The bulletin contains 24 articles, introduced by the Director's review for 1997, followed by a list of publications on Greenland issued in the Survey's own series and those scientific papers written by its staff published in international outlets. The articles report on onshore and offshore field work and on the main Greenland projects carried out during 1997. Several current research reviews are also included. A wide range of topics is touched on from geological and geophysical data on early Archaean to Quaternary rocks, to offshore geophysics and oceanography, with several papers dealing with petroleum and mineral exploration.

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