Danish and Greenlandic Minerals4EU INSPIRE Download Services (WFS 2.0) - M4EU Harmonized service contains mineral occurrences as points from Greenland and Marine sediments as polygons from Denmark

The development of this new magnetic compilation from Greenland was initiated by the working group of Satellite- and Aerogeophysics at the Christian-Albrechts-University (CAU) in Kiel, Germany, and GEUS as part of the ESA project GOCE+Greenland in 2021. The total magnetic intensity anomaly map from South Greenland is the first part of a compilation that will be stepwise extended to cover whole Greenland including the Inland Ice and the adjacent shelf regions. It is built out of all accessible modern regional aeromagnetic surveys from Greenland but also uses older datasets without GPS positioning in areas where modern data are lacking. Magnetic data are currently taken from the surveys of the AEROMAG and AEM projects (Rasmussen et al., 2013; Riisager & Rasmussen, 2014), GICAS project (e.g., Thorning et al., 1988), EASTMAR project (Larsen & Thorning, 1980), ICEBRIDGE project (see https://pgg.ldeo.columbia.edu/data/operation-icebridge ), GAP91/92 project (Brozena, 1992) and from offshore datasets acquired by the TGS-NOPEC TGS GEOPHYSICAL COMPANY. Since long wavelength components in aeromagnetic data are often considered as unreliable, they are replaced by the ones from the LCS-1 satellite model (Gaussian coefficients with degrees n = 13 – 133; Olsen er al., 2017). The magnetic map is generated by a methodology that combines equivalent source modelling and a spherical harmonic expansion. The datapoints at their actual measuring locations are used as data input and magnetic dipoles are employed as equivalent sources that are arranged in three uniform grids with different source spacing and depths (coarsest spacing: 10 x 10 km; finest spacing: 0.7 x 0.7 km). The presented total magnetic intensity map is simulated from the dipole responses at a constant height of 2000 m asl and with a grid spacing of 700 x 700 m. Regularizations in the inversion for the different equivalent source grids are chosen such that the resulting resolution is flexible and adapted to the largely varying magnetic data coverage in Greenland. A publication is in preparation that will provide more details about the data, methodology, implementation, and map quality. How to cite: Björn H. Heincke, Wolfgang Szwilius, Judith Freienstein and Jörg Ebbing (2023). A new magnetic compilation from Greenland built by a combination of equivalent source modeling and spherical harmonic expansion. Greenland Portal, https://maps.greenmin.gl/geusmap/?mapname=greenland_portal&lang=en References: Brozena, J.M. (1992). The Greenland Aerogeophysics Project: Airborne Gravity, Topographic and Magnetic Mapping of an Entire Continent. In: Colombo, O.L. (eds) From Mars to Greenland: Charting Gravity with Space and Airborne Instruments. International Association of Geodesy Symposia, vol 110. Springer, New York, NY. https://doi.org/10.1007/978-1-4613-9255-2_19 Larsen, H., & Thorning, L. (1980). Project EASTMAR: acquisition of high sensitivity aeromagnetic data off East Greenland. Rapport Grønlands Geologiske Undersøgelse, 100, 91–94. https://doi.org/10.34194/rapggu.v100.7707 Olsen, N., Ravat, D., Finlay, C., & Kother, L. K. (2017). LCS-1: A high-resolution global model of the lithospheric magnetic field derived from CHAMP and Swarm satellite observations. Geophysical Journal International, 211(3), 1461–1477. https://doi.org/10.1093/gji/ggx381 Rasmussen, T. M., Thorning, L., Riisager, P. & Tukiainen, T. (2013). Airborne geophysical data from Greenland. Geology and Ore – Exploration and Mining in Greenland, No. 22 – February 2013, 12 pages. https://eng.geus.dk/media/13207/go22.pdf Riisager, P., & Rasmussen, T. M. (2014). Aeromagnetic survey in south-eastern Greenland: project Aeromag 2013. GEUS Bulletin, 31, 63–66. https://doi.org/10.34194/geusb.v31.4662 Thorning, L., Bower, M., Hardwick, C., & Hood, P. (1988). Greenland ice cap aeromagnetic survey 1987: completion of the survey over the southern end of the Greenland ice cap. Rapport Grønlands Geologiske Undersøgelse, 140, 70–72. https://doi.org/10.34194/rapggu.v140.8039

The dataset contains the General Batymetric Chart of the Oceans (GEBCO) based on GEBCO_2019 Grid from 2019. The dataset has been projected to WGS 84 / IBCAO Polar Stereographic projection (EPSG:3996) and extends down to 50° latitude. The complete data set provides global coverage, spanning 89° 59' 52.5''N, 179° 59' 52.5''W to 89°: 59' 52.5''S, 179° 59' 52.5''E on a 15 arc-second grid. It consists of 43200 rows x 86400 columns, giving 3,732,480,000 data points. The data values are pixel-centre registered i.e. they refer to elevations at the centre of grid cells. The GEBCO_2019 Grid is a continuous, global terrain model for ocean and land with a spatial resolution of 15 arc seconds. The grid uses as a ‘base’ Version 1 of the SRTM15+ data set (Olson et al, 2014). This data set is a fusion of land topography with measured and estimated seafloor topography. It is largely based on version 11 of SRTM30+ (Becker et al, 2009; Sandwell et al, 2014), augmented with the gridded bathymetric data sets developed by the four Seabed 2030 Regional Centers. The published data were recalculated on a cell-registered grid for use by GEBCO. The GEBCO_2019 Grid includes data sets from a number of international and national data repositories and regional mapping initiatives.

The geophysical data available on the Greenland Mineral Resources Portal are both released company data and data acquired based on public funding (AEM and Aeromag surveys). The AEM Greenland 1994-1998 project, encompassed high resolution detailed multi-parameter surveys (electromagnetic, magnetic and partly radiometric) in the years 1994, 1995, 1996, 1997, and 1998 survey 1 and survey 2 producing a total of 75 000 line kilometres. The Aeromag projects, encompassed high resolution magnetic surveys conducted in 1992, 1995, 1996, 1997, 1998, 1999, 2001, 2012 and 2013 producing a total of more than 550 000 line kilometres. The projects were financed by the governments of Greenland and Denmark. More detailed information on the available geophysical date is given in Geology and Ore No. 22.

Basic information about the location of on- and offshore drillholes from Greenland for scientific research, mineral and oil and gas exploration. If available, a link to a report or summary sheet is specified that is the original source of information. The data is from 1948 through to 2019 and subject to change as new information becomes available from scientific reports, press releases and company documents.

All active exploitation licences. The data are converted from the WFS that th ministery of mineral resources (MMR) in Greenland provides. Links are provided in the online resources

Cross sections and map profiles from different geological maps and publications.

The dataset contains rock sample geochemistry collected from 1957 to 2007 in south to central west Greenland analyzed with different methods that have been published in 3 reports.

The AEM Greenland 19941998 are detailed surveys with combined electromagnetic and magnetic measurements that were carried out within a collaboration between GEUS/GGU and the Greenland Government in six selected areas of expected high mineral potential in Greenland. In total, 75 000 line km covering an area of 23 000 km² were measured in the project. Line spacing was 200 400 m (inline direction) and flight altitudes were typically around 120 m. With exception of one survey the collected electromagnetic data were time-domain data (GEOTEM system).

The digital terrain model of Greenland is constructed on the basis of GEUS's topographic data set from the official geological maps of Greenland in scale ratios 1:100 000 and 1:500 000. The data base is primarily supported by contour lines, coastlines and support points. The terrain model is assembled as a mosaic in sub-areas based on the map sheet frames from the geological map of Greenland in 1:500 000. The terrain model is made in the coordinate system WGS 1984 Complex UTM Zone 24N with the dimensions in a 100 x 100 m grid. Based on the digital terrain model, a shadow map of the terrain has been constructed.