Locality precision and accuracy

Rock samples were taken for different purposes. The earliest collected samples were mainly taken for mapping purposes. With time rocks were also collected for rock classification, petrogenesis and economic interests .

Mapping was done based on aerial photographs and sample localities were also found based on these. Most often aerial photographs with a 1:150.000 scale were used. The sample localities were marked on these images and have been digitized afterwards. Newer sample localities are more precise due to better quality of newer maps. Older samples have therefore a lower precision. Before 2000 analog methods were used to find sample coordinates.

After 2000 GPSs were used in the field to gather sample locality coordinates which improved their precision. In the first years of their use, not many GPS sattelites were present above the arctic region and therefore the precision and accuracy of sample coordinates can be low. Sometimes the number of decimals of a coordinate indicates a higher precision than is valid .Since then their accuracy and precision has greatly improved.

Geochemical analyses:

As mentioned above the samples were taken for different purposes and have been sent to different analytical laboratories with differing analytical precision and accuracy for the analyzed elements.The geochemical database has mainly been used as a raw storage system for geochemical analysis results. Therefore the quality of the data differs for different analytical sample results. The dataset contains analyses of up to 78 elements with bulk elements in weight %, trace elements in parts per million (ppm) and precious metals in parts per billion (ppb) Many cells are without content or have a value of 0 or negative values. Negative values and 0 values indicate that the analysisresult is below detection limit. In som cases values below detection limit are indicated with 99999. In some cases results with very large values are given as large rounded values of 10000. In many cases a sample was analyzed multiple times and multiple analytical results for a given element are given. In some cases these results can be highly variable and are dependend on the precision and accuracy in analyzing a given element with a given technique.