Browsing by discipline "Geology"

Petroleum hydrocarbons (PHCs) and heavy metals are common soil contaminants, which when released in the environment have the potential to damage plants as well as endanger the health of both humans and animals. Investigating these contaminations for cleanup purposes is therefore important, and developing new rapid techniques to aid in this process would be beneficial. VNIR-SWIR (350–2500 nm) reflectance spectroscopy is a well-known method that has been shown to be a promising tool for the rapid and costeffective mapping and monitoring of various soil contaminations. However, previous studies have mainly focused on the spectral features of soil contaminants; the anisotropic nature of reflectance and polarization have been largely ignored. Characterization of these reflectance properties has the potential to provide valuable additional information, that can be used to improve remote-sensing methods and help develop reflectance models for the quantitative and qualitative analysis of contaminants in soil. To study the bidirectional reflectance and polarization properties of petroleum hydrocarbons and lead, the Finnish Geodetic Institute Field Goniospectrometer (FIGIFIGO) was used to measure samples artificially contaminated with diesel, motor oil and lead in the laboratory as well as lead contaminated soil and vegetation at Suomenlinna, Finland. In total, 23 samples were measured. It was confirmed that petroleum hydrocarbons can be detected from their characteristic absorption bands, and that the 1730 nm band is the most significant for this purpose. However, clay minerals appeared to considerably lower the intensity of these bands and affect the reflectance. Despite this, hydrocarbon absorption features were successfully detected from all samples at a lowest measured concentration of 0.5 wt.%. The polarization in the backward direction was found to decrease when diesel or motor oil was added, while the polarization increased in the forward direction on low zenith angles. In order to better understand the relationships between clay, water, hydrocarbon and quartz contents and their combined effects on the reflectance, more studies are needed. The reflectance and polarization of the laboratory Pb samples were found to increase significantly in the forward direction, while the polarization decreased in the backward direction in the SWIR region. This characteristic, if investigated further, could prove useful for the detection of heavy metals in soil. Lead was not reliably detected from the field samples, but more controlled studies on the relationship between soil contaminations and polarization properties of vegetation should be considered.

Taalikkala megaxenolith is a fragment of the Wiborg rapakivi granite batholith roof. It is situated in Lappeenranta and has been exposed by the erosion. The geology of the area is exceptional because of the supracrustal rocks that have stratified on the bedrock before the fragment has detached from the roof of the magma chamber, flipped sidewise and sunk to the chamber. Quartz arenite has stratified atop of Svecofennian granodiorite and mica schist. Atop the discontinous quartz arenite there have formed rapakivi assosiated mafic and felsic volcanic and subvolcanic rocks. Based on lithologic, petrografic and geochemical studies, the volcanic rocks of the Taalikkala megaxenolith can be categorized in two main groups - the mafic and the felsic series. In both groups there is lithologic, petrologic and geochemical variation. In the mafic series the rocks are mainly tholeiitic whithin plate basalts. The felsic series rocks are acic volcanic and pyroclastic rocks. Geochemically, the felsic series rocks correlate both oxidized and reduced A-type granites. The stratigraphic thickness of Taalikkala supracrustal assosiation is about 1500 m and it is very similar to supracrustal rock assosiation in the Island of Suursaari (Russia) southwest of Wiborg batholith. A TIMS-data of the rapakivi porphyry shows that the crystallization age of felsic series is 1638 ± 3 Ma. The Wiborg rapakivi granite batholith represents a magma chamber that has erupted in several periods in Mesoproterozoic Era forming volcanic rocks that can be seen in the Taalikkala megaxenolith and the Island of Suursaari. The magma chamber (Wiborg batholith), the erupting channels (diabase dikes) and relics of lavas and pyroclastic stratas (bimodal volcanic rocks in Taalikkala and Suursaari) can all be seen today as reminders of the volcanic activities in Mesoproterozoic Era in southern Finland.

In 2009, mining company Anglo American found a significant Ni-Cu-PGE deposit in Sodankylä, Finnish Lapland. The deposit is located underneath Viiankiaapa mire and has later been named Sakatti. During the 1970s and 1980s, the Geological Survey of Finland carried out a targeting till geochemistry program that covered most of Finnish Lapland. The ore potential of Viiankiaapa was not recognized in the original research report from the area. The targeting till geochemistry dataset is an example of the vast amount of existing geological data that is publicly available but has not been widely used. The targeting till geochemistry results from Viiankiaapa area were reanalysed using modern methods to find out whether they contain any indications of the Sakatti deposit. Principal component analysis, k-means clustering and element ratios formed an effective combination to recognize the potentially mineralized samples. Self-organizing maps would have benefited from more detailed data. All methods were used first for the targeting till geochemistry data and then for combined datasets that included information about the Sakatti discovery. Clear indications of the Sakatti deposit were found in till samples adjacent to the known ore outcrops, where the samples had high Ni concentration and their element ratios were similar to the ore. The most significant limitation of the targeting till geochemistry data is the lack of stratigraphic information. The problem could be partly overcome by using recent stratigraphical interpretations from a different study. Even considering the weaknesses of the targeting till geochemistry dataset, results from Viiankiaapa show that it contains valuable exploration potential. The dataset could be used in ore prospecting surveys elsewhere to point out the most promising targets.

Tutkimuskohteena on Itä-Suomessa, Lapinlahden kunnassa Saarisen järven alueella sijaitseva pienehkö ultramafinen intruusio, joka poikkeaa selvästi sitä ympäröivistä arkeeisista TTG-assosiaatin kivistä. Lapinlahti sijaitsee Fennoskandian arkeeisen kratonin reuna-alueella ja geologiset rakenteet jakaantuvat sekä arkeeisiin että proterotsooisiin. Magmatismi on ollut alueella hyvin moninaista ja arkeeinen kallioperä on kokenut useita keski- ja korkean asteen metamorfisia tapahtumia. Saarisen intruusio on maa-aineksen peittämä muutamaa paljastumaa lukuunottamatta ja sen paikantaminen on tehty sähkömagneettisin ja magneettisin menetelmin ja kaikki tulokset perustuvat kairausaineistoon. Kairasydämistä tehtiin geokemiallisia kokokivianalyysejä, kiillotettuja ohuthieitä, elektronimikroanalyyseja, U-Pb-iänmääritys sekä Sm-Nd- ja Lu-Hf-isotooppianalyyysit. Kairasydänten raportointi tehtiin Kuopion GTK:ssa ja analyysit Espoossa Labtium Oy:n ja GTK:n laboratorioissa. Intruusiossa vuorottelevat hyvin runsaasti oliviinia sisältävät amfiboliittikerrokset ja -raidat. Paikoin amfibolin lisäksi on jäljellä vielä primääristä ortopyrokseenia. Saarisen ortopyrokseniitti on hyvin zirkonirikasta, mikä on epätyypillistä ultramafisille kiville. Paikoin kivet ovat muuttuneet täysin serpentiniitiksi ja kloriitiksi. Saarisen intruusiota leikkaa terävästi joukko proterotsooisia metadiabaasijuonia. Kairasydänten ja ohuthietutkimusten perusteella intruusiosta voidaan karkeasti erottaa noin 10 eri kivilajia: keskirakeinen porfyyrinen oliviiniamfiboliitti, tasarakeinen hornblendiitti, sarvivälkeperidotiitti, sarvivälkepyrokseniitti, pegmatiittinen ortopyrokseniitti, sarvivälkegabro, metamorfoitunut kvartsi-amfiboli-enstatiitti-granaatti-biotiitti-kivi sekä muutamia mineraalien muuttumisen tuloksena syntyneitä kivilajeja kuten kloriittiliuske ja serpentiniitti sekä metadiabaasi. Oliviini esiintyy hyvin runsaana lähes kaikissa ultramafisissa näytteissä ja niiden päämineraalit ovat oliviini, amfiboli, ortopyrokseeni. Aksessorisena mineraalina esiintyy runsaasti spinelliä ja ortopyrokseniitissä zirkonia. Saarisen ultramafisissa kivissä on varsin vähän mineraalivaihtelua. Sen sijaan mineraalien (erityisesti oliviinin) paljoussuhteet vaihtelevat paikoin suuresti, mikä monesti muuttaa myös kivilajinimeä. Kokokivianalyysien tulosten perusteella esiintymä on komatiittiskoostumuksellinen oliviiniortomesokumulaatti, joka ei ole rikastunut nikkelin suhteen. Hyvin magnesiumpitoisen koostumuksensa perusteella intruusio on todennäköisesti vaippasyntyinen. Saarisen intruusion on aiemmin tulkittu olevan läheisen Lapinlahden gabron satelliitti. Tämän tutkimuksen yhteydessä saadun ikämääritystuloksen (2643,6 ± 8,2 Ma) perusteella aiempi tulkinta sulkeutuu pois, sillä Saarinen on täysin eri-ikäinen kuin Lapinlahden gabro (1898 Ma) ja se eroaa iältään myös ympäristön arkeeisista gneisseistä ja migmatiiteista (jopa 3136 Ma). Initiaalisen neodyymin epsilonarvojen erojen perusteella Saarinen ei myöskään liity Kuhmon vihreäkivivyöhykkeen komatiitteihin, vaan on todennäköisesti itsenäinen kivilajiyksikkö.

The Kylylahti Cu-Co-Zn-Ni-Ag-Au sulfide deposit is located within the Paleoproterozoic North Karelia Schist Belt in eastern Finland about 25 km northeast from Outokumpu. The Kylylahti deposit is a part of the deformed and discontinuous chain of occurrences of Outokumpu assemblage in the Outokumpu area. Outokumpu assemblage refers to a lens-shaped serpentinized peridotite body enveloped by carbonate-skarn-quartz rocks. In the entire Outokumpu area the Cu-Co-Zn-Ni-Ag-Au massive to semi-massive sulfide deposits are hosted in the thin carbonate-silica alteration zones around the serpentinite bodies and are surrounded by black schists. The Kylylahti serpentinites are fine-grained and massive antigorite serpentinites. Tremolite skarns are abundant within the alteration zones of the Kylylahti massif. Previous seismic reflection data from the Outokumpu area includes OKU1, OKU2 and OKU3 survey lines acquired in connection with the Finnish Reflection Experiment FIRE in 2001–2005 and V1, V2, V3, V7, V8 and E1 survey lines in connection with the High Resolution Reflection Seismics for Ore Exploration HIRE in 2007–2010. The goals of this work were, 1) to estimate the seismic reflectivity characteristics of the Outokumpu-type ores and various rock types in the Outokumpu area, 2) to build a geological 3D model of the Kylylahti massif, 3) to use this 3D model and the estimated seismic velocity and density values for creating synthetic seismic sections over the Kylylahti massif in order to test for optimal 2D reflection seismic survey geometries and 4) to compare the synthetic sections with real reflection seismic sections already available from the Kylylahti area. For seismic forward modelling, a geological 3D model and densities and seismic velocities of different rock types are needed. Density values for each rock type were chosen from and compared with previous density measurements done in the entire Outokumpu area. Several rock types show a trend of increasing density towards Kylylahti. Seismic velocity values were either chosen from previous measurements or theoretically calculated from the density values. The geological 3D model of the Kylylahti massif was built with GOCAD® 3D modelling program and is based on drill holes and geological cross-sections of Kylylahti. The seismic forward modelling was done in GOCAD® Mining Suite with the BMOD3D-program which calculates synthetic seismograms using Born approximation theory. The modelled reflection seismic sections were compared with the real E1, V1 and V8 reflection seismic sections that cross the Kylylahti area. The forward modelling suggests that the geological 3D model used for the seismic forward modelling cannot fully explain the reflections seen on E1 and V1 sections. The lithological contacts of the 3D model are much too vertical to create as wide and continuous reflections as seen on E1. The Kylylahti massif may continue further southeast than the geological 3D model suggests as reflections indicate V1 section may crosscut talc-carbonate-skarn–serpentinite and black schist–talc-carbonate-skarn contacts. The less clear reflections on V8 section indicate that the parts of the massif that V8 crosses may be the less reflective mica schist–black schist contacts or the contacts within the Kylylahti massif are vertical at the location of V8. The most reflective parts of the Kylylahti massif are the black schist–talc-carbonate-skarn and talc-carbonate-skarn–serpentinite contacts. The ore has been modelled as an ore–black schist contact. If the contact is associated with density values and especially with theoretical seismic velocity values similar to those used for the modelling, the ore will produce a detectable signal, even if not very strong. A potential 2D seismic survey geometry in Kylylahti could consist of several seismic reflection lines along and perpendicular to the Kylylahti massif, taking into account that in the northern part the massive deviates about 20Ëš towards east from the north–south axis.

Enäjärvi is a shallow, longish lake in Southern Finland. The factors that led to its hypereutrophic state are a water level adjustment during the last century and a 25 years lasting point source nutrient load from sewage waters of Nummela. The restoration aimed at improving the status of the lake started in 1993. The improvement actions have included, inter alia, the oxidation of the hypolimnion, food chain restoration by removing roaches and the reduction of scatter load by building sedimentation basins, wetlands and border strips to the lake's catchment area. The lake is still highly eutrophic. Its surface sediment has been studied in two different years before. The first one was made in 1991, two years before the start of the restoration projects and the second one in 1999. In 1991 it was found out that the surface sediment was completely dark sulphide-colored gyttja that had poor nutrient retaining capacity. In the 1999 study the sediment had turned back to oxidiced, healthy sediment that worked as a sink for nutrients. The purpose of this thesis is to repeat those two studies. Together they will account of phosphorus retention monitoring in Enäjärvi for more than 20 years. The sampling was carried out in early spring 2013 from the same sample sites as in the earlier studies. The samples were taken from three different depths from 30 sample points. They were analyzed for water content, loss on ignition and total phosphorus. In addition the sediment surface layer was also analyzed for phosphorus fractions. The results were compared to previous findings with diagrams, percent change analysis, Sperman's rank correlation coefficients and regression line analysis. The water quality data collected by Economic Development, Transport and the Environment centre was also used to support the findings. The results of this study show that the restoration activities carried out on the lake have reduced the scattered loading to the lake and also bioturbation based leaching of phosphorus. The good quality of the surface sediment and the high content of redox-sensitive phosphorus fraction that increases with depth point out that the oxygen levels have remained high enough to bind phosphorus to metal oxides. Though at some sample points sediment surface had iron sulphide precipitates that point to depletion in oxygen level at the hypolimnion to some extent.

Sokli is located in the municipality of Savukoski in eastern Lapland, Finland, nearby the Russian border. GTK's research area of Kaulus is situated in the southern part of the Sokli carbonatite complex. The purpose of this work is to solve the petrography, geochemistry and P2O5-, Nb- and REE-mineralizations of rock types in the Kaulus region. In addition, the lithology of the area and the petrogenesis of these Devonian rocks are examined. A total of 1581.15 meters of drill core from 19 drill holes have been examined. Multi-element analysis has been done by XRF-method, trace elements have been analysed by ICP-MS-method and carbon has been analysed separately. From a total of 60 thin sections, 26 representative samples for the rock types of Kaulus have been selected, and were examined by EPMA, MLA and SEM. Some of the minerals have been imaged by BSE. The protolith rocks of Kaulus fenites are tonalite, granitic gneiss, gneiss, schist gneiss and amphibolite. The degree of metasomatism depends on the rock type and vicinity of carbonatite dikes. Felsic and intermediate fenites range from low-degree fenites through-medium degree fenites- to syenitic fenites. Phlogopitization reflect potassium metasomatism. No significant P2O5-, Nb- or REE-mineralizations were found in the fenites. Non-coherent mineralizations are local in respect to carbonatites. Metaphoscorites and metasilicocarbonatites are carbonated and alkali-metasomatized. The precursors of the metacarbonatites were probably magnetite olivinite, magnetite-olivine-amphibolite, olivine-pyroxenite, fenitized schist gneiss or gneiss and olivine-amphibolite. Metacarbonatites are enriched in P2O5 (2.6-4.0 %). Metaphoscorites occasionally have enriched Nb values (up to 1799 ppm), which may reflect to the composition of magmatic phoscorite. As CO2 concentrations increase in metacarbonatites, their REE-concentrations get similar with the REE-concentrations of carbonatites. According to average U/Th-ratios, Kaulus's carbonatites magmatic Stages have developed in the following order: magnesiumcarbonatite ≈ ferrocarbonatite → magnesiumcarbonatite → calciumcarbonatite → ferrocarbonatite → REE-carbonatite. Carbonatites have probably developed from metasomatized mantle at a depth of 70-80 km. Ferrocarbonatites and magnesiumcarbonatites may have acted as a source to the REE-carbonatites of magmatic Stage 5. The richest P2O5-concentrations are in calciumcarbonatites and ferrocarbonatites (3.3 % and 4.4 %, respectively). The richest Nb-concentrations are in the REE-carbonatites, ferrocarbonatites and calciumcarbonatites (1834 ppm, 1790 ppm and 1636 ppm, respectively). The average REE-concentration of the REE-carbonatites is 1.63 % and the maximum is 1.94 %. The Sokli Kaulus lamprophyres are possibly aillikites and metasomatic aillikites. The results indicate that the lamprophyres of Sokli were generated in shallower mantle depths (80 km) than the kimberlites of the Terskii coast (80-100 km).

Studies of the last ice age have been made in Finland since the early 20th century. The result is a wealth of information on activities related to the continental ice sheet and the location of the ice margins. The purpose of this thesis was to find out the usefulness of animations when visualizing research results. Animations have the advantage of sharing a large amount of information in a short time and they often are easier to comprehend compared to texts and images. In addition to this the aim was to visualize dynamics of the ice sheet and its ice margin positions. The materials from different studies that were used in visualization contain visual materials from ice sheet in northern Europe and more precisely from Finland. The animations were created by using ArcGis program and Blender 3D graphics software. In ArcGis the GIS-database was modified for suitable format to be used in Blender. Based on the visual materials, objects were formed in Blender from polygons that reflect the geometry of the ice sheet and its environment. The movements and other events were modelled by animating them and their visual look was formed by assigning different materials for different objects. Lastly, the animation was post-processed through composite and then rendered out of the program in the desired format. The results of the study were two animations about the activities related to the continental ice sheet in Northern Europe and Finland. The animation of Northern Europe is a general overview of growth and retreat of the ice sheet between 34–10 ka. The main result of the study is an animation of retreat of the ice sheet during deglaciation in Finland between 14–10 ka. The animation of the Finnish area visualizes ice lobes and stagnant ice areas between them. In addition to the ice sheet the animation also visualizes ice lakes, terminal moraines and calving of the ice sheet, as well as the sub-aquatic and supra-aquatic regions in Finland. The study can be further refined by adding all existing research data of ice margin positions and ice sheet dynamics. The animation regarding the ice sheet dynamics of Finland could be further expanded and refined towards areas in Norway, Sweden and Russia. In addition to that, one could add an elevation model and the development model of Baltic Sea and other water bodies to create a more diverse work. Based on the study, the usability of the animation in glacial geologic studies is significant when it is based on extensive research data and up-to-date glacial geological knowledge. The applications of animations are numerous and they can be used to generalize geological events.

This study reviews the thermophysical properties of rocks and the lithosphere and describes a one dimensional thermal numeric model of hypothetical 20 km thick overthrust plate obtruded on to the Archeaen craton in the Svecofennian orogeny (1.92-1.77 Ga). The objective is to find out if the overthrust plate and its radiogenic heat sources were able to produce the thermal effects observed on the current erosion level of the Archaean craton. Heat transfer in lithosphere is assumed conductive, and advective heat transfer due to melting and melt transfer is supposed negligible. The study area is located in the Eastern Finland, approximately current Kainuu and Northern Karelia regions, east from the most active orogenic belt (Raahe-Ladoga zone), so that orogenic magmatism can be neglected. Physical parameters and boundary conditions for the model are from different earlier published sources: deep seismic profiles (rock variation in depth), laboratory measurements (heat production and conductivity of rocks), field measurements (heat flow densities), and pT(t) estimations from the Finnish precambrian to estimate the size and thickness of the sheet. Comparison of the modelling results to previous K-Ar datings and other pTt estimations show, that the effect of the overthrust sheet has been adequate (max. T 450°C at 4 kbar) to produce the K-Ar resetting ages measured from the Archaean bedrock at current erosion level. No other kind of thermal activation in lithosphere is required. Results show possibly very minor partial melting in upper middle crust underneath the overthrust sheet.

The sampling was done in 2013 during the Integrated Ocean Drilling Program Expedition 347 on two sites in the river Ångermanälven estuary in Sweden. The area has had the highest rate of uplift in Fennoscandia since the last glaciation. The area was freed from ice 10 500 years before present, after which the shore displacement has been notable. The sedimentation environment has changed considerably from an ice proximal setting, through open sea to a less exposed estuary. The varve deposition is an ongoing process in the estuary since several thousands of years, and it has been correlated to annual discharge, which makes the estuary interesting for palaeoenvironmental studies. The aim of the study was to analyze the changes in the grainsize distribution and to link these changes to the environmental changes. The initial subsampling was made in Bremen in 2014 and the analysis in the laboratory of the Department of Geosciences and Geography of the University of Helsinki in 2015. A method, in compliance to the ISO 13320:2009 standard, was used in the laser diffraction particle size analysis. Also the water content and loss-on-ignition (LOI) was determined from selected samples. The results were processed with the statistics program GRADISTAT 8.0. The resulting figures were compared between the sites and displayed as a function of depth. The sediment consists of varying silt and sand deposits, in which both regular and irregular changes were seen. Interpretations of the sedimentation environments were made and compared with the results of earlier studies. At least three sedimentary units were recognized. Within the upper organic rich silt unit, the point of maximum salinity of the Baltic Sea was recognized. Also the effects of the shoreline displacement, as a coarsening of the sediment, with the decreasing distance to the source of the material, were noted. The unit was interpreted to the brackish Litorina Sea stage. The middle unit was more varied and the relationship between the two sites was more complex. A finer sample resolution would have been needed for an accurate interpretation of this unit. However the interpretation was the fresh water stage of the Ancylus Lake. The lower sandy unit showed indications of a glaciofluvial environment and also the change of distance to the source of the material. The interpretation was a fresh water lake and an ice proximal setting. This study utilized material from the CISU-project funded by the Academy of Finland (resolution 281143).