The Atlas samples of N Greenland package are described in Thrane et al 2011. This package builds on samples collected over a period from 1978 to 1999, holding old and newly acquired data. Some of the old samples have been reanalysed and together they have been quality controlled and compared. There are 2,644 unique samples in this package (65 of these samples are located under Soil samples). The geochemical analyses that are presented are above detection limit and readings below have been filtered out. Sampling The sampling density is not consistent throughout the covered area, and varies from 1 sample per 30 to 50 km2 to scarce and irregular in other areas. The regional geochemical surveys undertaken in North Greenland, follows the procedure for stream sediment sampling in Steenfelt, 1999. Thrane et al 2011, give more information sampling campaigns in the area. The sample consists of 500 g sediment collected from stream bed and banks into paper bags. In the filed the samples were dried and sent to Copenhagen for further drying and screening. Analyses was made on a split fraction < 0.1 mm size fraction.

The Geological Survey of Greenland (now part of the Geological Survey of Denmark and Greenland: GEUS) carried out a systematic 1 : 500 000 geological mapping program in North Greenland with fieldwork between 1978 and 1985 (Henriksen & Higgins 1991). One of many activities was a systematic programme of oblique aerial photography of the steep walls of fjords and valleys. This web-site makes available more than 6400 of these photographs. Using a map interface the user gain access to the individual images, their geological coding and the geological map).

Each map displays a grid image of the variation in element concentration, a colour scale giving class intervals for the grid colours, histograms showing the frequency distributions of sample values and grid cell values, respectively, and statistical parameters for measured concentrations in samples and for the grid cell values. All element concentrations below the lower limit of detection for the analytical method have been set to zero for simplicity, and in accordance with their registration in the GEUS database. Major element oxide concentrations have been recalculated as volatile-free concentrations to compensate for the effect of variable contents of organic matter and carbonate.

The regional-scale gamma spectrometry data are associated with two collaboration projects involving the Geological Survey of Greenland (GGU) and the Danish Atomic Energy Commission’s Research Establishment. The projects' objectives were to outline areas with an elevated uranium potential in two regions of Greenland: The airborne radiometric surveys in southern and central West Greenland in 1975/76 and the SYDURAN project in South Greenland in 1979-1982. To acquire the data, four-channel gamma ray spectrometers were mounted upon an aircraft (1975/76 surveys) and a helicopter (SYDURAN project). The vehicles flew along shoreline and valley contour lines at low average terrain clearances of 100 and 50 m respectively. The data were recorded without GPS systems, and so positioning was estimated when known landmarks were passed. This means that the dataset is sparse and inhomogeneous, and the spatial accuracy remains low. The gamma-spectrometer had been calibrated at a pad facility at Risø, which enabled the conversion of recorded counts per second into simulated concentrations of radioactive components in the surface of the overflown terrain. Large parts of the data (surveys from 1975/76) were originally stored on magnetic tapes and data were transferred to datafiles in 2003 to make them digital accessible. Most data were retrieved and are now available as ASCII files.

The gravity compilation is based on data stored in the national/Nordic gravity data base at the DTU Space. This data base contains for Greenland data surveyed by DTU Space on behalf of the geodetic survey authorities “Danish Agency for Data Supply and Efficiency” (SDFE) and its predecessor agencies “National Survey and Cadastre” (KMS) and the Geodetic Institute (GI), with some data dating back to the 1950’s. Older data have been rectified into modern gravity datums (absolute gravimetry and IGSN71). The national data contains both surface, airborne and marine data, mainly in the coastal ice-free regions and offshore (Forsberg et al, 2001, Kenyon et al, 2008). Airborne, marine and land data from a number of external data sources are also included in the data base after a QC process, including high-level airborne data from the GAP91/92 campaigns (Brozena et al, 1993) and recent data from NASA OIB (MacGregor et al., 2021) and OMG projects (Fenty et al., 2016). Marine data in the Baffin Bay and Davis Strait and land data from the Geodetic Survey Division, Canada (Veronneau 2010, pers.comm.), and a number of other marine and land data from a large set of contributors have also been included in the compilation, including marine data from Alfred Wegener Institute (Germany), land and marine data from Orkustofnun (Iceland), and a number of released commercial data sources. In areas void of gravity data, satellite-derived altimetry data have been used as fill-in (DTU 15, Andersen et al. 2017). The compiled grids have been based on public domain and some proprietary data sources, and has been computed for the area 58-85°N, 78-7°W on a 0.02°x 0.05° grid, using rigorous downward continuation of airborne data to the terrain surface, with terrain corrections from a detailed digital terrain and ice sheet surface model, and long-wavelength satellite gravity data from GRACE and GOCE satellites (Forsberg and Olesen, 2010). The data are available as a free-air (Faye) anomaly grid as well as a derived terrain-corrected Bouguer anomaly grid (land and ice sheet areas only), computed in GRS80 with density 2.67 g/cm3. The ice sheet Bouguer anomaly data are derived using the ice sheet thickness model of Bamber et al., 2013. The free-air gravity grid (v1) have also have been used as the primary background data also for the latest geoid models of Greenland (GGEOID16).

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

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.

In the present database there are 1269 unique samples. Soil samples have been collected in areas without river beds. Preferably stream samples have been collected, but areas where temporarily no stream beds are present, soil samples have been collected as an alternative for geochemical mapping purpose. Five samples in this package are originally from the report Compilation of data sets for a geochemical Atlas (Steenfelt, 1999). These samples have been analysed by "UNKNOWN" methods at "UNKNOWN" laboratories. In fact these samples have been calibrated and corrected for analytical bias, see Steenfelt 1999, for further information.

The regional aeromagnetic datasets were acquired from the Alfred Wegener Institute for Polar and Marine Research (AWI), Bremerhaven, Germany, in four field campaigns along the coastal regions of Northeast Greenland from 1993-1996. The line spacing ranges both in inline and crossline direction from 10-40 km and the levels range up to 3700 m. Presented maps are based on data reprocessed by GEUS.

The Raw stream sediment samples dataset is data as they have been delivered from the laboratories, i.e. values below detection limit often spelled as negative but zero may also apply. The data are not controlled by a geologist. In addition, they may not have been reported.