Plants have been used as sample media in exploration around the world with positive results. Vegetation assimilates metals together with nutrients it actually needs from the soils, these concentrations can then be analysed. Which element is assimilated and to what degree, is different from species to species and can vary depending on the plant tissue sampled.

This study investigates weather sampling of Scots Pine (Pinus sylvestris) twigs constitutes a reliable and efficient exploration method to use in the Gällivare area, Northern Sweden. Three areas have been examined for this Master’s thesis. In Area 1, two different subareas were studied, a surface mineralization that has been partly mined (Area 1.1) and a known blind mineralization (Area 1.2). Area 2 has been selected due to discoveries of several copper- and gold-rich boulders in the area, whose provenance is still uncertain. Area 3 served for establishing background values.

Sampling took place in October 2016 at all sites. All samples collected were from Scots Pine (Pinus sylvestris) and, as often as possible, from trees with a stem circumference of about 40cm and a healthy appearance. Branches of pine were cut from a height of four to five meter of the tree using a pole snipping tool. Twigs of 10cm length and 3-5mm diameter with needles on were then collected from the branches using a hand held snipping tool. The samples had a fresh weight of about 200g each and were put in decomposable paper bags with sample number and lab number written on them. Tools were not cleaned between every sample, plant fragments stuck on the tools were simply shaken off. All the samples was collected by hand within two days and sent to ALS Scandinavia AB  laboratory within a week after the sampling.

The data from the Area 1.1 indicates that anomalous concentrations of metals and some REE (rare earth elements) occur in pine twigs above and around the surface mineralization. Patterns are not as clear for all elements as hoped and might have be disturbed by the previous mining activity in the area. In addition, the rocks in the area are heavily altered and smaller of mineralizations may occur in local shear zones. However, the data from the pine twig sampling does show some differences in element composition in the trees growing over the main known mineralization. 

Area 1.2 does not show any clear patterns in metal- or REE elements, and values are generally much lower than at the other two areas. It may be so that the mineralization is located too deep to get any indication from pine twig sampling. The alteration elements did not show any clear patterns either, which is probably due to the small dataset. A larger sampling grid over the mineralization might be able to show an alteration zonation over the area.

Area 2 show very similar patterns in almost all elements studied in this report and has similar ranges of values, sometimes even higher concentrations, than Area 1.1. This may indicate that Area 2 also hosts a mineralization. 

Sampling of pine twigs is a fast method; two people could collect up to 30 samples/day with a grid size of 200m x 150m. The sample weight of 200g/sample makes it possible for one person to carry many more samples than for example soil samples, before they would need to return to the car and unload. The equipment needed for sampling is easy to use and does not weigh much, which makes it possible to carry a whole day in forest terrain.