Zircon age data as gathered from literature and GEUS samples

This view presents data selected from the geochemical mapping of North Greenland that are relevant for an evaluation of the potential for zinc mineralisation: CaO, K2O, Ba, Cu, Sr, Zn. The data represent the most reliable analytical values from 2469 stream sediment and 204 soil samples collected and analysed over a period from 1978 to 1999 plus a large number of reanalyses in 2011. The compiled data have been quality controlled and calibrated to eliminate bias between methods and time of analysis as described in Thrane et al., 2011. In the present dataset, all values below lower detection limit are indicated by the digit 0. Sampling The regional geochemical surveys undertaken in North Greenland follows the procedure for stream sediment sampling given in Steenfelt, 1999. Thrane et al., 2011 give more information on sampling campaigns in the area. The sample consists of 500 g sediment collected into paper bags from stream bed and banks, alternatively soil from areas devoid of streams. The sampling density is not consistent throughout the covered area and varies from regular with 1 sample per 30 to 50 km2 to scarce and irregular in other areas. Analyses were made on screened < 0.1 mm or <0.075 mm grain size fractions.

The Samba database among other things contains information about deep wells in the Danish sector, acquired according to the Danish Act on the Use of the Subsoil. That is: exploration, appraisal, delimitation and production wells related to oil/gas. Also wells with other purposes such as: geothermal energy, gas storage, salt production and scientific research. The data sets contains technical, administrative and geological information about the well and about the geophysical measurements undertaken in the well (well logs and reports). Data are submitted by the company to whom the permission has been granted. The database is updated on an ongoing basis.

The dataset contains outlines of archived historical unpublished geological maps and sections of Greenland mostly created by GGU and GEUS but also some other institutes from 1916 onwards at various scales.

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 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 digital geological map shows the surface geology. The map is a result of the systematic geological mapping of Denmark. The map is digitized from maps originating from fieldwork, where sediment samples are collected at 1m depth using a hand auger with a sample spacing of 100 - 200 m. This version 6 from 2021 classifies 91 % of Denmark's area. The map is supplemented in an ongoing process. The legend shows 82 different sediment types. The map is published in GEUS report 2021/68, where further information is available in Danish.

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.

Uniform aerial photographic coverage of Greenland was achieved in 1978-1987 at 1: 150 000 scale by Mark Hurd Aerial Surveys, Inc., Minneapolis, Minnesota, U.S.A., for the Danish Geodetic Institute [Weidick, 1995]. The photography is now administered by the Danish Geodata Agency, see also http://eng.gst.dk/maps-topography/greenland/aerial-photos-of-greenland. The camera used for these black and white photographs was a Wild RC 10 with a super wide angle lens (focal length = 88 cm). The airplane used by Mark Hurd was a Gates Lear Jet 25C. By setting the flying height to app. 14 km the image scale of 1:150 000 was achieved [Bengtsson & Jørgensen, 1980]. In an attempt to avoid blind areas, caused by the precipitous mountainsides in combination with the use of a super wide angle lens, the photographs were taken with a length-lap of 80%, and a side-lap of 40%. In the subsequent use of the photography (for aerotriangulation, mapping and scanning) generally only every other image were used (as you will see from the photo number shown on this web-page). The photo center coordinates are from the aerotriangulation by the Danish Geodata Agency. Please contact GST for the high resolution photos.

GEUS' Earthquake Portal provides information on all recorded earthquakes in Denmark. The data are extracted from GEUS' earthquake database and are updated daily. As a result, the timing, locations, and magnitudes of events may change as new data are added and existing events are revised. Continuous quality control is carried out, aiming to identify and remove explosions – typically related to military exercises or the removal of old munitions. Therefore, the list may change over time, and some uncertainty may be associated with the determination of epicentres and depths. The portal displays information for each earthquake, including the time of occurrence (year, month, day, hour, minute, second) in Greenwich Mean Time (GMT), the geographical location and depth of the epicentre, and the local magnitude measured on the Richter scale. Earthquake data can be exported from the portal according to the defined zoom level and map extent.