Search

Lineaments, linear structures on the surface of the Earth, often represent the surface expressions of brittle structures, e.g., fault zones and fracture zones, or ductile shear zones. In addition, they may also represent other geological features such as lithological contacts, tectonic boundaries and Quaternary structures, or potentially a superposition of any of these. A lineament interpretation is usually the first step in the structural assessment of a crystalline bedrock setting, and the lineaments can further be used as basis for scientific research to more accurately determine the location of the previously mentioned various geological features. In this study, a multi-source lineament interpretation was performed within ArcGIS for the whole of Finland, based on light detecting and ranging (LiDAR), aerogeophysical and bathymetric raster data. The lineament database enhances the capability to produce more accurate geological maps for various geological purposes in Finland.

Understanding the local stratigraphy and geometry of sediment units is necessary for successful 3D modelling and the prediction of ground behaviour and engineering-geological properties for urban land use and construction. A detailed 3D model of the main sediment units for the Rastaala basin in southern coastal Finland was constructed, combining a conceptual geological model and information from local drill-hole logs and geotechnical drilling. The 3D modelling was based on a cross-section approach, where sediment units were defined on the basis of lithological boundaries that are of major geotechnical importance for land use and construction. The conceptual geological model was based on a sequence of events that characterize the late- and postglacial evolution of the Rastaala basin. The present study combines the allostratigraphy and lithostratigraphy of unconsolidated glacial, late-and postglacial sediment units in southern coastal Finland. It also investigates the appearance and distribution of sediment units in the Rastaala basin and compares modelling and visualization results for unit surfaces and solids using two independent modelling software packages. Finally, information on the geotechnical properties of different sediment units in the Rastaala basin is provided so that they can be applied to other onshore regions with similar geological settings in the coastal Baltic Sea Basin.

A soil moisture estimation method was developed for Sentinel-1 synthetic aperture radar (SAR) ground range detected high resolution (GRDH) data to analyze moisture conditions in a gently undulating and heterogeneous subarctic area containing forests, wetlands, and open orographic tundra. In order to preserve the original 10-m pixel spacing, PIMSAR (pixel-based multitemporal nonlocal averaging) nonlocal mean filtering was applied. It was guided by multitemporal statistics of SAR images in the area. The gradient boosted trees (GBT) machine learning method was used for the soil moisture algorithm development. Discrete and continuous in situ soil moisture values were used for training and validation of the algorithm. For surface soil moisture, the root mean square error (RMSE) of the method was 6.5% and 8.8% for morning and evening images, respectively. The corresponding maximum errors were 34.1% and 33.8%. The pixelwise sensitivity to the training set and method choice was estimated as the variance of the soil moisture values derived using the algorithms for the three best methods with respect to the criteria: the smallest maximum error, the smallest RMSE value, and the highest coefficient of determination (R-2) value. It was, on average, 6.3% with a standard deviation of 5.7%. Our approach successfully produced instantaneous high-resolution soil moisture estimates on daily basis for the subarctic landscape and can further be applied to various hydrological, biogeochemical, and management purposes.

Land-use conflicts can be costly and time-consuming and cause social burden to all parties. In this study, we developed an approach for mapping synergy and conflict potential between land uses and tested it on nature protection, nature-based tourism, forestry and mining. First, we calculated the ecological and socio-cultural values for the study area, and further the economic values related to forestry and mining. Second, we conducted an integrated spatial assessment of these values and used it jointly with a variant of a value compatibility analysis to locate areas with possible synergistic and conflicting land uses. This study was carried out in Finnish Lapland where land use conflicts have occurred due to the need to develop forestry and mining in areas that are also important for nature-based tourism. The method operated well as it identified sites with ongoing land-use disputes. Synergy potential between biodiversity and socio-cultural values was identified in protected areas and other sites of natural beauty, and conflict potential concerning forestry near tourist resorts and concerning mining at proposed mining project sites. The developed framework can assist in locating sites that may need proactive measurements to avoid conflicts, and sites that would benefit from multi-purpose management thereby supporting sustainable and adaptive land-use planning.

The ages and sizes of landslides occurring in seismically active areas can be used to reconstruct the seismic history of the area and estimate the maximum moment magnitudes of past earthquakes. Here, we present a data set of 121 landslides discovered in northern Finland that were analyzed for their morphometric characteristics. We show that 89 debris slide type landslides in the data set are clustered close to known postglacial faults (PGFs) and thus provide information on the characteristics of postglacial paleoseismic events. By using empirical correlations between the landslide volume–area data and earthquake moment magnitude, we estimate maximum moment magnitudes M w ≈ 6.9–7.7 for postglacial earthquakes in the Suasselka, Isovaara–Riikonkumpu, Venejarvi, and Vaalajarvi areas, where earlier estimates based on fault length and displacement have yielded magnitudes varying between M w ≈ 6.5 and 7.5. We also show that the landslides in northern Finland are located within a radius of 35 km from the closest known PGF and that sizes of the landslides decrease as a function of distance from PGFs, hence providing strong empirical evidence for their seismic origin. As far as we are aware, this is the first use of landside data in quantifying postglacial seismicity within the Fennoscandian Shield area.

•The Aijala tailings pond was characterized as an example of the secondary raw materials target in the EU.•ERT, IPT, and gravity and magnetic and electromagnetic methods were utilised.•Soil drilling and geochemical analyses with 1-m intervals enabled mineral resource estimation.•Best survey combination was gravity with adequate number of soil drills and geochemical analyses.

Finland is a Northern country where mineral exploration and mining has significantly increased during the 2000s. At the same time there occurs competition over the right to use land and ecosystem services. Main competitors over land with mineral exploration and mining industry are especially tourism, reindeer herding, and environmental protection. In this study we combine information over geology, location, timescales, and uncertainty to provide mineral related foresight tools: 1) Mine potential tool, and 2) Mineral deposit potential tool. The former is applied to known mineral deposits and targeted mineral exploration, the latter to regional mineral exploration. Cases presented include Sodankyla for nickel, Kolari for iron, copper and gold, and Kittila for gold. In a long-term foresight, the usefulness of information on mineral exploration licenses proved limited. Better support for the long-term foresight is given by geological potential (prospectivity), time framing and narrative probabilities for known mineral deposits. Visualising the long timescales and uncertainties in a spatial context is the greatest value of these foresight tools. Also the concept of ‘deposit archive’, adopting those detected mineral deposits that have proven uninteresting or uneconomic in the current market environment, provides a valuable insight to availability of raw materials in a long term together with the adaptation of the assessment of undiscovered mineral resources.

The development of mining and other resource-based industries are among key drivers of economic development in the Arctic. The fragile environment and the presence of nature-based livelihoods and indigenous communities pose challenges for mining development. Mining operations should be optimized so that the profitability is maintained in changing market conditions and to meet increasing societal and environmental demands. In this study we present the current understanding on the interplay between mining and the surrounding socio-ecological systems in the Arctic region. The existing academic literature on the Arctic region was reviewed, covering 127 peer-reviewed publications since 2000. We investigated the mining activities from four perspectives examining: 1) environmental, 2) economic, 3) social and 4) legal dimensions, covering three life-cycle stages: 1) pre-mining, 2) mining, and 3) post-mining. The publications on the environmental and economic aspects focused principally on the impacts of mining, whereas social and legal publications discussed the interaction between people and their rights and ways of controlling their environment. Besides the need for more balanced research between different life-cycle stages we uncovered five research gaps concerning the knowledge base needed to increase the sustainability of Arctic mining: 1) impacts and adaptation to climate change, 2) monitoring the sustainability of mining using standardized indicators, 3) holistic economic assessment of mining, 4) social sustainability and conflict management, and 5) mechanisms that mitigate or compensate for the adverse effects of mining on biodiversity.

Ground-penetrating radar (GPR) was used to locate fractures and distinguish fracture properties at the laboratory and field scales. Laboratory studies were performed to define the effects of fractures on the GPR signal. In the laboratory, a fracture between two blocks of crystalline rock was filled with water or air, and the aperture of the fracture was varied from 0.75 to 10 cm. Air-filled and water-filled fractures were successfully distinguished on the basis of GPR signal polarity changes. Moreover, it was possible to estimate the fracture aperture when it was wider than the vertical resolution of the antenna. For instance, the resolution of a 800-MHz antenna enables the detection of 1-cm-wide water-filled openings. Armed with knowledge of the signal behavior at the laboratory scale, the apertures and the filling materials of fractures were also estimated in uncontrolled field conditions. These field studies were carried out in a dimension stone quarry of migmatitic granodiorite located in Southern Finland.

Understanding the behaviour of uranium is essential when assessing the safety of a spent nuclear fuel repository. The geochemical behaviour of uranium, including its reactive transport chemistry, is also a matter of concern when assessing the environmental impact of uranium mining. Subsurface uranium mobility is believed to be primarily controlled by dissolution and (co)-precipitation of uranium mineral solids and adsorption to mineral surfaces. This paper describes a modelling exercise based on characterisation of samples taken from drilled cores at the uranium mineralization at Askola, Southern Finland. In the modelling exercise, current conditions are assumed to be oxidizing and saturated with groundwater. PHREEQC was used for modelling in conjunction with the Lawrence Livermore National Laboratory database, chosen for its extensive coverage of uranium species and mineral phases. It is postulated that weathering processes near the surface have led to uranium dissolution from the primary ore, leaching out from the matrix and migrating along water-conducting fractures with subsequent re-diffusion into the rock matrix. Electron microscopy studies show that precipitated uranium occupies intra-granular fractures in feldspars and quartz. In addition, secondary uranium was found to be distributed within goethite nodules as well as around the margins of iron-containing minerals in the form of silicate and phosphate precipitates. Equilibrium modelling calculations predict that uranium would be precipitated as uranyl silicates, most likely soddyite and uranophane, in the prevailing chemical conditions beneath Lakeakallio hill.

The aim of this paper was to study effect of an opening to GPR signal, measured with 800 MHz and 1600 MHz transmitter/antenna. Tests were carried out in laboratory scale using two sawn rock blocks. The opening between them varied from 0 to 10 cm. First GPR signal’s velocity was defined in the blocks by calculating two way travel time, as the thickness of the blocks was known. Next the top and bottom of the opening were interpreted from the GPR profile by utilising theoretical change of the reflected signal’s phase in the opening. Openings apertures were calculated from the interpretations and compared to the real ones. Good results were achieved for the greatest apertures, but apertures smaller than 1/6 of the signals wavelength could not be interpreted due to signal summing. Summing could be less of a problem when using other filling materials than air in the opening. These are the next research subjects for the authors.

Interpretation of trace metal mobility in geological environments is often hampered by conflicting data from alternative experimental protocols and the lack of detailed mineralogical characterization of the host medium. To illustrate this issue, the release of uranium, thorium and the rare earth elements (REE) was investigated in polished rock slab samples from the U-Th deposit at the Palmottu Natural Analogue study site (SW Finland) by means of leaching experiments. The samples were sequentially leached with artificial groundwater of moderately high carbonate content at pH8, and nitric acid solutions at pH5 and pH3. The mineralogy and composition of the U, Th and REE mineral phases was studied using SEM-WDS and EDAX methods before and after each leaching step. In parallel, leaching was carried out on crushed material of the same samples and the leachates analysed by ICP-MS.The most notable U minerals are uraninite, uranophane and two secondary U-Pb phases. Thorium occurs predominantly in monazite and at lower concentrations in uraninite. Accessory thorite is also present, which together with monazite contains most of the REE. Differential leaching of the elements was noted across all phases on the timescale of the experiments. Uraninite is partly dissolved at pH3. The main secondary uranium phase, uranophane, was stable in moderately acidic solution, but easily dissolved in the artificial groundwater and at pH3. Some release of REE was observed although the main REE-bearing phase, monazite, showed no evidence of degradation.This study provides insights in the preferential release of radionuclides in granitic bedrock. An understanding of these processes is essential when assessing the safety of a spent fuel repository. Once released from the primary waste form U is expected to precipitate as secondary phases within micro fractures, as observed at Palmottu and numerous other deposits.

Uranium is a major radioactive constituent of spent nuclear fuel and high-level radioactive waste. However, its migration behaviour in crystalline rocks is still inadequately understood. This paper describes the results of controlled laboratory migration experiments and attempts made to simulate them using numerical models. Initial models employing generic information in “blind predictions” are progressively enhanced by data-supported interpretation. Such an approach is intended to mimic the stages of a site assessment, where conceptual and numerical models are progressively refined.