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Browsing by master's degree program "Magisterprogrammet i geologi och geofysik"

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  • Dimakopoulos, Georgios (2022)
    The metamorphosed Kutemajärvi gold deposit is located near the town of Orivesi, at the eastern flank of the Tampere Schist Belt, which constitutes part of the Svecofennian domain of southern Finland, and it is hosted in the volcanic rocks of the Koskuenjärvi formation. Previous isotopic studies have mainly focused on the igneous and metamorphic rocks of the Tampere Schist Belt and only a few of them have presented ages for the area of Kutemajärvi. This study aims to shed light on the timing of mineralization by employing the single-grain U-Pb dating method of monazite and zircon, in order to evaluate the relationship between the ore and its host rocks. Based on the results from the SEM mineral identification, monazite grains are divided into metamorphic and hydrothermal grains. In the case of zircon grains, a third magmatic type has been identified. Results from U-Pb dating of single monazite and zircon grains are well constrained and document four distinct stages of geodynamic evolution in the region. Ages older than 1.91 Ga represent detrital material transported during the stage of rifting that led to the opening of the Tampere basin. Subsequent subduction resulted in active volcanism which is expressed with the extrusion of the Koskuenjärvi formation at 1904 Ma. At the late stages of subduction or at the outset of the collision stage, the subvolcanic Pukala porphyry intruded into the volcanic sequence of the Tampere Schist Belt at 1890 Ma, which provides the maximum mineralization age. Release of hydrothermal fluids, due to the crystallization of the Pukala intrusion caused pervasive hydrothermal alteration of the Kutemajärvi host rocks and deposition of epithermal gold and other elements. However, the participation of hydrothermal fluids, released by high-temperature metamorphism of the lower crust, cannot be ruled out. Ages between 1890‒1878 Ma record the syn-collision stage, during which the deposit, the Pukala intrusion and its adjoining rocks were deformed and metamorphosed at greenschist to lower-amphibolite facies. The majority of ages fall within the 1880‒1878 Ma time-interval, characterizing the metamorphic peak that marks the culmination of the Svecofennian orogeny and provides a minimum age of the mineralization. This major orogenic event is partly overlapped by the collision of the Central Svecofennian Arc Complex with the Southern Svecofennian Arc Complex that transpired at 1880‒1860 Ma, as indicated by ample age data. Monazite and zircon also yield lower ages (<1860 Ma), which record retrograde metamorphic and subordinate cooling events, and resonate recurring tectonothermal activity, associated with the syn- and post-collisional magmatism of Southern Svecofennia and the emplacement of rapakivi intrusions in southern Finland. Single-grain U-Pb dating of monazite and zircon from polished thin sections, in tandem with collation of the obtained ages with earlier published data, establishes a spatial and temporal framework with respect to the tectonometamorphic evolution of the Kutemajärvi gold deposit and the Tampere Schist Belt. Precise temporal constraints substantiate the intricate geological history of the area and can be used to discriminate magmatic, metamorphic and hydrothermal events, with a view to breaking ground on the exploration of other epithermal deposits in the metamorphic terranes of southern Finland.
  • Jimenez Reyes, Debanhi (2023)
    In Estonia and Gotland, Sweden Ordovician and Silurian rocks can be found in exposed outcrops, they have been studied for the past years to create a better understanding of the biological and geological events that transpire during the Ordovician and Silurian. Finland is not known to have sedimentary fossiliferous limestones, but the Åland Islands is one of the places where Ordovician and Silurian erratic limestones can be found. The limestones were glacially transported from the Bothnia Sea area. The erratic limestones found in the Åland Islands have not been studied and have not been dated. The goal of this research is to reconstruct the depositional age of the erratic crinoidal limestone from the Åland Islands through 13C, 87Sr/86Sr, and identification of microfossil proxies. We used in situ strontium isotope analysis by MC-ICP-MS and 13C analysis in different materials of the sample, the materials analyzed were cement, sediment matrix, and skeletal material (crinoid stem). The samples were sent to experts for microfossil identification. The Åland samples were compared with known samples from Estonia and Gotland. The samples from Niibi Estonia showed the most petrographical similarities and were also analyzed for strontium and carbon isotopes. The strontium analysis showed that the material had a different strontium signal, which then contributed to diagenetic alteration due to rubidium-87. It was observed that the sediment matrix was the most susceptible to any diagenetic alteration followed by the skeletal material and then the cement. There were conodonts found in the Åland samples that indicated that the erratic limestone is from the lower Haljala Regional Stage, Sandbian, Late Ordovician.
  • Koskela, Elina (2019)
    Tiivistelmä/Referat – Abstract This study investigates temperature data that Posiva Oy has from the Olkiluoto and ONKALO® sites. The aim of the study was to create a unifying data classification for the existing temperature measurements, give an estimate of the initial undisturbed bedrock temperature and temperature gradient and model the temperature profiles in 3D. The thermal related issues, which the repository will undergo once in operating are significant and have fundamental contribution to the evolution of the repository, creating a need in such a study. Posiva Oy has temperature data obtained with four main methods; Geophysical drillhole loggings, Posiva flow log (PFL) measurements, thermal properties (TERO) measurements and Antares measurements. The data classification was carried out by creating a platform of quality aspects affecting the measurements. The classification was then applied for all the available data by inspecting the measurement specifics of each configuration and by observing the temperature/depth profiles with WellCad software. According to the specifics of each individual measurement the data was classified into three groups: A= the best data, recommended for further use, and which fulfils all quality criteria, B= data that should be used with reservation and which only partly fulfils quality criteria, and C= unusable data. Only data that showed no major disturbance within the temperature/depth profile (class A or B) were used in this study. All the temperature/depth data was corrected to the true vertical depth. The initial undisturbed average temperature of Olkiluoto bedrock at the deposition depth of 412 m and the temperature gradient, according to the geophysical measurements, PFL measurements (without pumping), TERO measurements and Antares measurements were found to be 10.93 ± 0.09°C and 1.47°C/100m, 10.85 ± 0.02°C and 1.43°C/100m, 10.60 ± 0.08°C and 1.65°C/100m, and 10.75°C and 1.39°C/100m, respectively. The 3D layer models presented in this study were generated by using Leapfrog Geo software. From the model a 10.5 – 12°C temperature range was obtained for the deposition depth of 412 – 432 m. The models indicated clear temperature anomalies in the volume of the repository. These anomalies showed relationship between the location of the major brittle fault zones (BFZ) of Olkiluoto island. Not all observed anomalies could be explained by a possible cause. Uncertainties within the modelling phase should be taken into consideration in further interpretations. By combining an up-to-date geological model and hydraulic model of the area to the temperature models presented here, a better understanding of the temperature anomalies and a clearer over all understanding of the thermal conditions of the planned disposal location will be achieved. Based on this study a uniform classification improves the usability of data and leads into a better understanding of the possibilities and weaknesses within it. The initial bedrock temperature and the temperature gradient in Olkiluoto present thermally a relatively uniform formation. The estimates of the initial bedrock temperatures and the temperature gradient presented in this study, endorse previous estimates. Presenting the classified temperature data in 3D format generated good results in the light of thermal dimensioning of Olkiluoto by showing distinct relationships between previously created brittle fault zone (fracture zone) models. The views and opinions presented here are those of the author, and do not necessarily reflect the views of Posiva.
  • Voutilainen, Ahti (2021)
    A new ground motion prediction equation, named ON21, is solved for the ST1 Deep Heat enhanced geothermal system in Otaniemi, city of Espoo, Finland. The raw data from seismic events, that occurred during the stimulation of 2018, is processed, instrument response is removed, and frequency domain is used to obtain peak ground displacement, velocity, and acceleration. A database with 20,768 ground motion recordings from 204 events is compiled and used to solve a ground motion prediction equation for peak ground velocity and acceleration for vertical and horizontal movement. The model has a magnitude range from 0.0 to 1.8 on the scale of local magnitude used in Finland, and hypocentral distances of 0 km to 20 km. A 1σ value of 0.60 for vertical peak ground velocity model is lower than the 1σ of the models previously in use at Otaniemi and its surrounding areas. It is observed that the azimuth between the strike of the fault causing the earthquakes and the station recording the events seems to affect the peak ground motion values at a hypocentral distance of no more than 10 km, and beyond that the magnitude and distance are the dominant factors in the peak ground motion values. The new ground motion prediction equation model ON21 should be tested with ground motion data from earthquakes that occurred during the 2020 stimulations to assess its usefulness in predicting peak ground motion values, and to further study the effect of azimuth on the peak ground motion values.
  • Hekkala, Toni (2019)
    Arsenic (As) is a metalloid naturally present in the environment. Arsenic species vary in toxicity. Metal mining has contributed to the anthropogenic input of arsenic to groundwaters and surface waters. In this study, water samples were collected from 20 sample points in three mining-impacted study areas in Finland: the former Ylöjärvi Cu–W–As and Haveri Au–Cu mines, and the active Pyhäsalmi Zn–Cu mine. Six groundwater well samples, eleven surface water samples and three tailings seepage collection ditch samples were analyzed for dissolved arsenic speciation by HPLC-ICP-MS and for geochemical composition by ICP-MS, titration, and ion chromatography. Dissolved arsenic concentrations ranged from 14.2 to 6649 µg L-1 in samples collected at the Ylöjärvi study area, from 0.5 to 6.2 µg L-1 in samples collected at the Haveri study area, and from 0.2 to 9.4 µg L-1 in samples collected at the Pyhäsalmi study area. In all study areas, measured dissolved arsenic concentrations showed a general decrease from the tailings to the surroundings. Speciation analysis showed that two of the samples collected at the Ylöjärvi study area had arsenite [As(III)] as the dominant form of dissolved inorganic arsenic (iAs), three had arsenate [As(V)] as the dominant form of dissolved iAs, and four had a mixture of both. In the water samples collected at the Haveri and Pyhäsalmi study areas, all concentrations of dissolved arsenic species were below method detection limits. Also, none of the 22 water samples analyzed for arsenic speciation had dissolved MMA or DMA concentrations above method detection limits. Identification of dissolved arsenic species in the sampled waters in Haveri and Pyhäsalmi, and of MMA and DMA in all sampled waters requires more detailed study. A significant 2-tailed Pearson correlation between dissolved arsenic and dissolved molybdenum (Mo) (r=0.80**, n=20), and dissolved arsenic and dissolved potassium (K) (0.68**, n=19) suggests that in these three study areas the distributions of dissolved arsenic and Mo, as well as dissolved arsenic and K may be controlled by the same environmental variables. Anomalously high maximum concentrations of dissolved Al, Ca, Co, Cu, Fe, Ni, and SO4 were measured in surface water samples collected at the Ylöjärvi and Haveri study areas, and in a seepage collection ditch sample collected at the Pyhäsalmi study area.
  • Sandell, Mia (2023)
    Evolution can lead to changes in body size among mammals and when that occurs, organs usually scale along. Teeth are an organ that scale along with body size and therefore, investigating how the teeth are getting along when a mammal is subjected to a rapid reduction of body size is of value. During human evolution, body size has generally increased but jaw and teeth size has decreased. As of recent, human evolution witness a potential decrease of body size, due to the discovery of island-living hominins; Homo floresiensis and Homo luzonensis. The phenomenon of decreasing body size among large animals and increasing body size among small animals in an insular setting is so well-known that it has its own ecological rule, called the island rule or Foster’s rule. However, this phenomenon has not really been studied from the perspective of teeth. In this thesis I focus on the effects of body size decrease on teeth in the context of relatively rapid body size reduction. Researching the effect that a reduction of body size has on teeth is relevant for understanding morphological changes related to island dwarfism and the origins of island forms among humans. Dogs (Canis familiaris) provide an extreme example of rapid and large reduction of both body- and teeth size. Comparing dog molars to molars of their closest ancestor, the wolf (Canis lupus), can shed light on how the teeth behave when scaling down in size. This reduction in body size may be comparable to insular dwarfing as selective breeding of pure breed dogs is limiting the availability of mating partners in a similar way that a secluded island limits the availability of mating partners for insular animals. To answer my research questions, I measure and photograph dog molars and compare the results with data of wolf molars. Furthermore, if any patterns emerge, data of human molar is compared to the canid data to investigate if any similarities can be found. The results show that dog molars are overall smaller in size than wolf molars and that both species follow a pattern where m1 > m2 > m3. Furthermore, small dogs are more likely to have an absent m3 than big dogs and wolves. Moreover, the results show that the size relation between dog m1-m2 is a continuum of wolf m1-m2 relation. However, dogs have enlarged their m3 and therefore the m2-m3 size relation is not a continuum of wolf molar relation. When comparing the human data to the results of dog/wolf m1-m2 and m2-m3 size relation, the results show that Homo floresiensis molars are on the same trajectory as Homo erectus molars. This implies that dogs have done adjustments to their molars that diverge from their ancestors’ molars and that the change has happened during a short period of time. Therefore, dog molars cannot be seen as simply scaled down version of wolf molars, as far as size is concerned. The information gained from this thesis can be used to further investigate if molars of other rapidly dwarfed species may have behaved in a similar manner. It is however too early to say if dogs can be seen as an island rule simulation or if they can shed light on the origins of hominin island forms. More research, such as comparing the number of cusps between dog and wolf molars or investigating the upper carnassial and the following molars, needs to be done to be able to draw any further conclusions.
  • Karjalainen, Aino (2020)
    NMR Services Australia (NMRSA) Pty Ltd has developed a Borehole Magnetic Resonance (BMR) tool which is based on the principles of nuclear magnetic resonance (NMR). Drillhole NMR tools have been used mostly in sedimentary environments for oil and gas exploration while applications in hard, heterogeneous, crystalline bedrock are still lacking. This study aims to test the BMR method in a hard rock environment, and for determining hydrogeological parameters in the spent nuclear fuel disposal site, the Olkiluoto island. Essentially, the objective is to design an optimal BMR data processing workflow and calibrate the estimated hydrogeological parameters, currently optimized for data from sedimentary environments, to suit the crystalline bedrock. For testing the BMR method in hard, crystalline bedrock, Posiva Oy, the Finnish expert organization responsible of spent nuclear fuel disposal, made test measurements in the drillholes of the spent nuclear fuel repository site, island of Olkiluoto. The collected data was processed with WellCAD software using additional NMR module. The BMR tool derives T2 distribution (representing pore size distribution), total porosity, bound water and moveable water volumes and permeability calculated with two different models. Some processing parameters (main/burst sequence, moving averages, temperature gradient, cutoff values) were tested and adjusted to fit into crystalline bedrock. Magnetizing material of the surface environment strongly disturbed the uppermost ~20.0 m portions of the measurement data. Some noise was encountered also deep in bedrock, which was cut away from the signal. A list of criteria was created for recognizing noise. The BMR data was compared with other drillhole data acquired by Posiva, i.e. fracture and lithology logs, seismic velocities and hydrogeological measurements. It was observed that the T2 distribution and total porosity correlate rather well to logged fractures and seismic velocities. Lithological variations did not correlate to BMR consistently, mostly because of the strong dependency on fracturing. Permeabilities were compared to earlier conducted hydrogeological measurements, with an intention to calibrate the permeability calculation models. However, this proved to be challenging due to the significant differences of the BMR method and conventional hydrogeological measurements. Preferably, the permeability models should be calibrated by laboratory calibration of the drillhole core, and possibly a new permeability model suitable for crystalline bedrock should be created.
  • Erhovaara, Suvi (2023)
    Northern peatlands are important carbon storing ecosystems, contributing to carbon cycle as sinks and sources. The two most important greenhouse gases in the carbon cycle are carbon dioxide (CO2) and methane (CH4). The study area of this work consists of two sloping fens in the Kuusamo area. from which the peat geochemistry and peat properties (peat stratigraphy, ash content, and bulk density) are studied. In addition, the chronology, carbon-nitrogen ratio, carbon content, and carbon accumulation are studied in the Puukkosuo from the three sampling sites. In the characterization of peat geochemistry, Puukkosuo in the dolomitic rock area and Suvisuo in the volcanic rock area were divided into different geochemical zones based on the cluster analysis. The paludification in the Puukkosuo area has started around 10 000 years ago, and the accumulation of peat have been ongoing in the whole peat basin after 1000 years. The geochemical zones in the Puukkosuo can be divided into five different groups, from which the deepest part of the peatland basin can be separated due to the high heavy metal concentrations in the oldest peat. Most of the bulk peat is differentiated into alternating groups, from which the changes in the peat nutrients are recorded. The margins of the Puukkosuo are separated based on the geochemical properties. The top part of the northwestern edge can be characterized as high concentrations of atmospheric origin elements, whereas the effect of the nearby road can be noted in the concentrations of the top part of the southeastern edge. The amount of carbon accumulated has varied throughout the development of Puukkosuo, and the highest rates are recorded in the lower part of the peat profiles in all study sites. Highest carbon-nitrogen -ratios are recorded near the basal peat samples especially in the deepest part of the Puukkosuo. The long-term carbon accumulation differs from the other long-term averages in the boreal zone. The largest differences were recorded in the deepest part of the basin in the long-term carbon accumulation rates during the Early Holocene. The respective value in the Puukkosuo is four times higher (60 g m-2 yr-1) in contrast to others. During the Late Holocene the long-term carbon accumulation rates correspond to the other average values in the boreal peatlands (25 g m-2 yr-1).
  • Liimatainen, Toni (2022)
    Graphite is formed mainly by graphitization processes from organic precursor in high-grade metamorphic conditions, or precipitation of carbon from carbon-bearing fluids. Quality of the graphite, i.e. crystallinity, flake size and purity, determines its use and commercial value. Demand for graphite has been on the rise and is expected to increase more in the near future. The Korsnäs region in Ostrobothnia, Western Finland, is a prominent target for a graphite exploration based on the region’s geological history, i.e. the Svecofennian accretionary orogeny and high-grade metamorphic conditions. Graphite is ubiquitous in the area, and has been enriched mainly in the metapelitic schists intercalated within the paragneisses. The aim of the master’s thesis is to study the mineralogical characteristics and quality of the graphite, as well as estimate the economic importance of the graphite occurrences in the area of Korsnäs. Additionally, the origin of the graphite formations and their relationship to the regional metamorphic conditions are considered in this research. Mineralogical characteristics and quality of the graphite flakes were studied from the polished thin sections with optical microscopes and scanning electron microscope. Crystallinity of the graphite flakes was analyzed by a Raman spectroscopy, which has been used widely to measure orderly structure of a carbonaceous material. Peak temperatures of the metamorphic conditions were estimated from the Raman results using geothermometers. Based on the petrographic analysis, graphite is abundant, and the morphology refers to a flake graphite. Large proportion of the flakes are over 0.3 mm on their c-axis, which can be considered as large and the most valuable type of a flake graphite. Crystallinity of the graphite was determined from the Raman spectra using the peak intensity ratio (R1) of the graphite band and the main disordered band. The analyzed graphite flakes show good values for the R1 parameter (mean value 0.05 ± 0.05), indicating high crystallinity, and consequently, high-grade metamorphic conditions or precipitation from carbon-bearing fluids for the formation mechanism. The estimated peak temperatures are ranging from 650 to 695°C, which are consistent with the mineral assemblages of the migmatite and paragneiss samples, but inconsistent with the graphite-bearing metapelitic schists. The biotite-garnet and biotite-garnet-cordierite (sillimanite) paragneisses does not show any meaningful evidence of a retrograde overprint, but it is apparent that the graphite bearing samples have experienced retrograde metamorphism and hydrothermal alteration. This is evident from the lack of high-grade metamorphic minerals, presence of lower metamorphic grade minerals, and the estimated high peak temperatures for the formation of the graphite. Consequently, the R1 parameter suggests that the graphite in these rocks has not been affected by the retrograde metamorphism. The origin of the high-crystalline graphite appears to be a graphitization of biogenic material, but fluid-deposited graphite cannot be completely ruled out. Some carbon enrichment may have occurred by fluid-rock interactions. Further studies and detailed analyses, such as locating the possible high-grade deposits and determining the purity of the graphite, are needed. In conclusion, the high-crystalline graphite in the Korsnäs region is of good quality and shows prominent results for the commercial value.
  • Tuikka, Leevi (2023)
    On the hotter Paleoproterozoic Earth, the regime of plate tectonics was likely in transition, including features from the early Earth but having e.g. subduction already established. The different mode of tectonics affected also on the deformation on plate boundaries, on orogenesis, for example. Due to the increased lithospheric temperatures, the Paleoproterozoic orogens were hotter and lower. Such conditions made also HP-LT metamorphism rare. In addition to the different temperature conditions, the past tectonics pose another challenge. Largely the Paleoproterozoic rocks that can be accessed today, are the remnants of ancient middle or lower crustal layers, which have exhumed due to deep levels of erosion. Hence, a great amount of evidence of past orogens is erased. To overcome this issue, geodynamic modeling is used to build set of 19 continent-continent collision models, with the temperature conditions ranging from the Paleoproterozoic to the Phanerozoic. Additionally, P-T-t paths are recorded in the models for comparison of pressure-temperature conditions using pseudosection diagrams. Another significant quantity governing the deformation on collisional continental margins, is the angle of convergence obliquity. With roughly 60° obliquity, full strain partitioning should be triggered in a orogen, forming a strike-slip fault. In the models, different temperature cases with the obliquity angle are varied. The geodynamic modeling software to produce the models was DOUAR, a 3D thermo-mechanical code coupled with erosion model FastScape. The initial models with 35 km thick crust were not able to produce proper strain partitioning due to low resolution, so another set of models with 45 km thick crust was run. On top of that, the lower crustal strength was varied. Outcome of the thicker crust was wider orogens, and hence more space for strain partitioning to develop. However, strain partitioning was not able to be preserved that well for the whole 40 Ma, which was the runtime of the models. Though in terms of strain partitioning, the results were not ideal, the angle of obliquity affected on the crustal shear zones as well, in a interesting way.
  • Koskimaa, Kuutti (2020)
    AA Sakatti Mining Oy is researching the possibility of conducting mining operations in Sakatti ore deposit, located partially under the protected Viiankiaapa mire. In order to understand the waters in mining development site, the interactions of surface waters, shallow aquifers, and deep bedrock groundwaters must be understood. To estimate these interactions, hydrogeochemical characterization, together with four tracer methods were used: Tritium/helium, dichlorodifluoromethane and sulfur hexafluoride, stable isotopes of hydrogen and oxygen, and carbon-14. Most of the shallow groundwater samples are similar to the natural precipitation and groundwater in their chemical composition, being of Calcium bicarbonate type. B-11-17HYD013 was an exception, containing much more Cl and SO4. The samples from the deep 17MOS8193 all show a very typical composition for this type of a borehole, on the line between the saline Sodium sulphate and Sodium chloride water types. The samples from the 12MOS8102, as well as the river water samples and the Rytikuru spring sample are located between these two end members. The hydrogen and oxygen isotope values divided the samples into two distinct groups: those that show evaporation signal in the source water, and those that do not. The most likely source for the evaporated signal in the groundwaters is in the surface water pools in the Viiankiaapa mire, which have then infiltrated into the groundwater and followed the known groundwater flow gradient into the observation wells near the River Kitinen. Tritium showed no inclusion of recently recharged water in the deep 17MOS8193, and dated most of the shallow wells with screen below bedrock surface to be recharged in the 70’s and 80’s. B-10-17HYD017 had an older apparent age from 1955, and B-14-17HYD006 was curiously dated to be recharged in 2018. 14C gave apparent age of over 30 000 a for the deep 17MOS8193. The slight contents of 14C could be caused by slight contamination during sampling meaning the age is a minimum. The sample M-4-12MOS8102 got an apparent age of ~3 500 a, which could in turn be an overestimate due to ancient carbon being dissolved from the local bedrock fractures. CFC-12 showed apparent recharge dates from 1963 to 1975 in the shallow wells, and no recently recharged water in the deep 17MOS8193, and so was generally in line with the 14C and Tritium results, although some contamination had happened. SF6 concentrations exceeded possible concentrations considering other results, most likely due to underground generation, and the method was dismissed. By trace element composition, all samples from the deep 17MOS8139 are distinct from other samples and saw slight dilution in concentrations of most elements in the span of the test pumping. Other samples are more mixed and difficult to interpret, but some trends and connections are visible, such as the higher contents in wells with screens below the bedrock surface than those with screens above the bedrock surface, and the exceptionally high contents of many elements in B-13-17HYD004. Overall, the study did benefit from the large array of methods, showing no interaction between the deep bedrock groundwaters and shallow groundwaters or surface waters. The evaporated signal from the Viiankiaapa was clearly visible in the samples close to the River Kitinen.
  • Douglas, Regan (2024)
    Mesowear, a method that scores the wear of teeth to determine the amount of abrasive material in the diet, has long been used to understand palaeoecology though the diet of herbivores. Until recently, proboscidean teeth could not be used for these studies. The method of mesowear angle analysis introduced by Saarinen et al. in 2015 has made this possible by measuring the relative angle between the enamel ridges and dentine valleys of the lophs of proboscidean teeth to account for wear. This study compares the average mesowear angles of 428 specimens of Pleistocene Mammuthus to determine geospatial variation across the genus as well as within the species M. primigenius. These results are then corroborated with previous studies of other palaeoecological proxies to ensure they truly reflect a means to determine palaeoecology through proboscidean mesowear. Overall, this study finds that significant geospatial variation and little interspecific variation of Mammuthus proves that mammoths were highly adaptable herbivores capable of surviving in a wide array of the harshest habitats and browsing or grazing habits were not determined by species morphologies, but the environments they inhabited.
  • Kettunen, Ilkka Henrikki (2022)
    Aim of this study is to develop biogeochemical exploration methods for cobalt. Several different samples were collected from study area, analyzed, and compared to each other. This study took place at Rautio village at North Ostrobothnia and more accurately over the Jouhineva mineralization. Jouhineva is well-known high-grade cobalt-copper-gold mineralization. Elements examined in this study are cobalt, copper, arsenic, zinc, selenium, and cadmium. Samples were collected from three different study profiles from the area. From these three profiles samples collected are: soil, pine, lingonberry, birch, rowan, and juniper. Water samples were collected around the study area from every location possible. Soil samples were analyzed with four different methods: Ionic leaching, aqua regia, weak leaching and pXRF. Ionic leaching and aqua regia had both elevated concentrations of cobalt, but in different locations depending on study profile. Ionic leaching detects rising ions from the ore and therefore elevated concentrations are found at different locations compared to aqua regia. Aqua regia results proved how different orientation of study profile, direction of the ore and glacial flow can affect to the anomalies of elemental concentration. Profile-2 was oriented differently to ore and glacial flow than Profile-1, and therefore elevated concentrations of cobalt and copper were not drifted away from the ore on Profile-2 like they were on Profile-1. Aqua regia and pXRF have very similar copper, arsenic and zinc results. Pine and lingonberry turn out to be the most promising plant species applied for cobalt exploration, and rowan appears to be most suitable for copper exploration. Lower detection limit could significantly improve pine analyses as exploration method and more extensive sampling could remove some of the uncertainties about the method. Lingonberry samples have elevated concentration of copper and arsenic. Birch and juniper produced somewhat unclear results. Despite this, cobalt and copper concentrations in birch leaves were elevated when compared to concentrations found in other studies. In addition to this birch is suitable for arsenic exploration. Juniper had elevated copper concentration in the study area compared to other studies. Water samples collected from the Jouhineva area yielded concentrations of cobalt, copper and arsenic that were above the average concentration in the Kalajoki area waters. Copper and arsenic were above the average concentration of the Kalajoki area in every sample collected from the study area. Cobalt was above the average concentration in all samples that were not collected directly from the pond formed in the old test mine. Zinc concentration was below the average limit in all samples collected from the area. Zinc concentration in the water samples collected from the pond is significantly lower compared to the other samples collected from the area.
  • Redmond Roche, Benjamin Heikki (2019)
    Significant changes in sea-ice variability have occurred in the northern North Atlantic since the last deglaciation, resulting in global scale shifts in climate. By inferring the dynamic changes of palaeo seaice to past changes in climate, it is possible to predict future changes in response to anthropogenic climate change. Diatoms allow for detailed reconstructions of palaeoceanographic and sea-ice conditions, both qualitatively, using information of species ecologies and quantitatively, via a transfer function based upon diatom species optima and tolerances of the variable to be reconstructed. Three diatom species comprising a large portion of the training set are proxies for the presence of sea ice: Fragilariopsis oceanica, Fragilariopsis reginae-jahniae and Fossula arctica, have currently been grouped into one species – F. oceanica – in the large diatom training set of the northern North Atlantic region. The clustering of the species may result in an imprecise reconstruction of sea ice that does not take into account all the available ecological information. The proportions of the three species were recounted from the original surface sediment slides alongside the additional chrysophyte cyst Archaeomonas sp. and statistically analysed using Canoco and the R software package eHOF. A core from Kangerlussuaq Trough comprising the Late Holocene (~690–1498 Common Era) was also recounted and analysed using C2. The separated diatom species and chrysophyte cyst Archaeomonas sp. exhibited different relationships to both sea-ice concentration (aSIC) and sea surface temperature (aSST). The separated F. oceanica is a ‘cold-mixed’ water species occurring at cold aSST and both low and high aSIC. High abundances occur in the marginal ice zone (MIZ) where surficial meltwater is high during the spring bloom, with additional inputs from glacial meltwaters nearshore. F. reginae-jahniae is a sea-ice associated species related to cold aSST and high aSIC. High abundances occur in the low salinity Arctic Water dominated MIZ which experiences significant aSIC. F. arctica is a sea-ice associated species related to cold aSST and high aSIC. High abundances occur in the low salinity Arctic Water dominated MIZ which experiences high aSIC, particularly in polynya conditions. F. arctica can be considered a characteristic polynya species at high abundances. Archaeomonas sp. is a ‘cold-mixed’ water species related to both cold and relatively warm aSST and low and high aSIC. High abundances occur in both relatively warm ice-free Atlantic Water and also in cold high aSIC Arctic Water conditions rendering it a more complex indicator for aSST or aSIC proxy. However, the aversion to MIZ conditions indicates that Archaeomonas sp. is associated with a relatively saline unstratified water column. This is the first time that the distribution and ecology of Archaeomonas sp. has been presented. As such, the ecology described here can be used in future studies. The separation of the three diatom species is crucial for the ecological interpretation of downcore assemblage changes. It is also crucial for the application of transfer functions in order to have greater precision in reconstructing aSIC and assessing the influence of Arctic Water or Atlantic Water, even at low abundances.
  • Orozco Ramírez, Lilia Estefanía (2019)
    The European Water Framework Directive aims at restoring all water bodies in good ecological conditions by the year 2023. For this aim, understanding the responses of these ecosystems to current and future pressures is a requisite. Lakes Hältingträsk and Storträsk are located in Östersundom, a latent developing suburban area in eastern Helsinki. Alterations to the catchment in Hältingträsk as a consequence of urbanization will likely change the conditions of the lake. Storträsk, part of Sipoonkorpi nature reserve is primarily influenced by recreational activities. Ecological status of both lakes is likely to alter under the ongoing urban development. For this reason, the reference conditions of Hältingträsk and the resilience of both lakes to human stressors must be assessed. A long term record from Hältingträsk, with special focus on the most recent section, as well as a short core from Storträsk targeting the most recent events, are analyzed for different palaeobiological and geochemical proxies. The sequence from Hältingträsk is evaluated with diatom assemblages, trace metal analyses, lithological description of sediments through loss-on-ignition and inferred chlorophyll a. For Storträsk, a high-resolution study of diatom communities and photosynthetic pigments is performed. Both sequences are framed with an age-depth model based on radiogenic dating techniques. In addition, the results are analyzed with statistical tools and fossil diatom data is used to reconstruct lake water pH. The results describe the evolution of Hältingträsk through the mid-Holocene until recent times; the diatom assemblages indicates the area was part of Ancylus Lake and, later of Litorina Sea, and that it was isolated from the Baltic Basin at 6500 cal BP. This is supported by the high concentrations of Fe and Mn, showing the presence of metallic nodules common in marine environments. The change in sediments and the predominance of fragilarioid diatoms, display the succession of the lake (from gloe to flada). Afterwards, the ontogeny of the lake and the development of surrounding peat bog can be tracked with changes in the diatom community and decrease in heavy metals concentrations. The reconstructed pH reveals that Hältingträsk is a naturally acidic lake. Furthermore, signals of agricultural activities and industrialization are recorded in the area, as well as their development, is recorded through shifts in the diatom community and the oscillation of trace metals of both local (Cu, Ni and V) and long (Pb, Zn and Cd) transport. Finally, climatic anomalies such as the Little Ice Age and current climate warming are imprinted in the diatom assemblages and the photosynthetic pigments. The high resolution of subsampling from Storträsk displayed little variation. The faint changes could be attributed to CaCO3 treatment, fish introduction or recent climate warming. However, discern the influence of each of these stressors was not possible.
  • Hopiavuori, Juuso (2024)
    The need caused by climate change and the pursuit to use natural resources more efficiently has accelerated the search for new alternatives to fossil fuels. This has increased the popularity of geothermal energy, of which the most common and versatile energy system is the Enhanced Geothermal System (EGS). An unavoidable byproduct of EGS power plants is seismicity, which occurs particularly during hydraulic stimulation to enhance the flow of heat transfer fluid in the bedrock. Stimulation significantly increases the seismic risk in the area to a level well above the natural state, thus increasing the probability of significant earthquakes. To minimize the risks and damages caused by significant seismic events, it is important to determine the maximum credible earthquake magnitude (Mmax) for EGS projects. Mmax serves as a crucial parameter in seismic risk assessment, defining the largest possible magnitude event that can be reached during the injections. This work investigates the ST1 Deep Heat project that operated in Otaniemi, Espoo, during which two stimulations were conducted in 2018 and 2020. The combined seismic risk from these stimulations has not yet been evaluated in terms of the Mmax and the probability distribution of magnitudes. In this study, we aim to determine the Mmax value for Otaniemi based on a probabilistic approach, using the method presented by Shapiro et al. (2010), where the Gutenberg-Richter relation is modified by incorporating the seismogenic index and the volume of injected fluid. This work suggests that the value of Mmax produced by the Otaniemi stimulations is M2.33. Therefore, the probabilities for significant earthquakes are low, indicating a low seismic risk. When previous studies are complemented with the effects of the 2020 stimulation, this study shows that the 2018 stimulation is the main contributor to the seismic risk in Otaniemi and that the increase in seismic risk from the 2018 stimulation to the end of the 2020 stimulation is small. The results of this work show that the seismogenic index can be used to estimate Mmax and probabilities of significant magnitudes from statistical injection-based data and provide structural geological justifications for these results. The results support the idea that injection-based Mmax is the result of the interaction between injection strategy and natural seismotectonic conditions. The lower seismicity of the 2020 stimulation can be explained by these factors. In EGS operations, the injection strategy is crucial for managing the seismic risk. The seismogenic index determined in this study describes the seismotectonic state of the Otaniemi reservoir. Once determined, it can be used in future studies or projects focusing on the Otaniemi reservoir and boreholes. It is also possible that another geologically similar reservoir would have a similar seismogenic index, which would allow the findings of this study to be applied to the assessment and management of similar risks elsewhere. Continued and high-quality research is a requirement for the development of policies and methods to make geothermal energy production safer in the future. This research provides information on the relationship between EGS operations and induced seismicity and will increase the understanding of induced seismicity and its hazards in general.
  • Uusikorpi, Juuso (2020)
    The geochemical regolith data gathered from Dzhumba, a gold prospect in eastern Kazakhstan, was analyzed using factor analysis and then integrated into ArcGIS as spatial data. Principal axis factoring method was used for factor extraction combined with varimax orthogonal rotation and Kaiser normalization. Five clear factors were extracted from the data set of 47 elements in 3942 regolith samples. Kriging interpolation was used to generate spatial data surfaces from factor scores. The generated factors are composed of the geochemical associations in the raw data, and represent the underlying geological processes and formations of the area. The fourth factor generated represents gold mineralization with As, Sb, Au, Zr, Sc, Mn, Mo, Cu, K and Ni being the elements that are positively loaded onto factor 4. Therefore, single element maps of these elements have been produced alongside the factor maps in order to examine factor 4 more intensely. Also maps about structural geology and alteration in the Dzhumba project area have been produced in order to give better understanding of the factor maps. The data suggests that the deposit type is an orogenic gold deposit. Other factors created interesting results as well, and they gave information about the different geological units of the area. Factor 1 represents granitic rocks by their feldspar and trace element content, factor 2 represents black shales with possible mafic rock constituents, factor 3 represents a sulfide rich mafic mineral group or graphitic rocks that are most likely black shales and factor 5 possibly represents calcite alteration. Factor 4 is the main interest of this study. The most intense loadings for factor 4 are in Brigadnoe, Svistun and Dzhumba with a small peak in Belyi. Single element map for gold mostly corresponds to factor 4 for Svistun and Dzhumba, but Brigadnoe is represented with a small peak. However, gold has a major presence in Fedor-Ivanovskoe, which is absent from factor 4. Further exploration in Fedor-Ivanovskoe could be performed in order to clarify if this is due to an unrelated gold-only deposit or some other event. Possible future exploration in the area could benefit from factor 4 results, using As and Sb, or a combination of As, Sb, Zr, Sc, Mn, Mo, Cu, K and Ni as pathfinders for possible gold occurrences.
  • Ylä-Mella, Lotta (2020)
    Terrestrial cosmogenic nuclides can be used to date glacial events. The nuclides are formed when cosmic rays interact with atoms in rocks. When the surface is exposed to the rays, the number of produced nuclides increases. Shielding, like glaciation, can prevent production. Nuclide concentration decreases with depth because the bedrock attenuates the rays. The northern hemisphere has experienced several glaciations, but typically only the latest one can be directly observed. The aim of the study was to determine if these nuclides, produced by cosmic rays, can be used to detect glaciations before the previous one by using a forward and an inverse model. The forward model predicted the nuclide concentration with depth based on a glacial history. The longer the exposure duration was, the higher was the number of nuclides in the rock. In the model, it was possible to use three isotopes. Be-10, C-14 and Al-26. The forward model was used to produce synthetic samples, which were then used in the inverse model. The purpose of the inverse model was to test which kind of glacial histories produce similar nuclide concentrations than what the sample had. The inverse model produced a concentration curve which was compared with the concentration of the samples. The misfit of the inverse solution was defined with an “acceptance box”. The box was formed from the thickness of the sample and the corresponding concentrations. If the curve intersected with the box, the solution was accepted. Small misfit values were gained if the curve was close to the sample. The idea was to find concentration curves which have as similar values as the samples. The inverse model was used in several situations, where the number of limitations was varied. If the timing of the last deglaciation and amount of erosion were known, the second last deglaciation was found relatively well. With looser constraints, it was nearly impossible to detect the past glaciations unless a depth profile was used in the sampling. The depth profile provided a tool to estimate the amount of erosion and the total exposure duration using only one isotope.
  • Sandström, Joonas (2021)
    Aijala-Metsämonttu volcanogenic massive sulphide ore deposit belongs to Orijärvi regional volcanogenic massive sulphide mineralisation, localised within the schist zone southwestern Finland. Aijala-Orijärvi zone is an island-arc structure formed during the Paleoproterozoic (1895-1891 Ma). The mining operation in Aijala took place in 1949–1958 and Metsämonttu in 1952–1958 and 1964–1974. The Aijala and Metsämonttu deposits were 1 km apart. The main ore types were massive vein-like pyrite, sphalerite, pyrrhotite, chalcopyrite, and galena. The purpose of this thesis was to produce modern geological 3D models of the Aijala and Metsämonttu volcanogenic massive sulphide ore deposits and numerical grade models of the utilised minerals (copper, lead, zinc, silver, and gold) using historical material and to interpret the occurrences and emplacements of precious metals and base metals. In addition, compare the accuracy of the 3D models with digitised historical material. Geological 3D and numerical grade models were created using implicit modelling. Historical data used in this thesis consist of 266 drill holes from Aijala and 274 drill holes from Metsämonttu. Also, 61 mine tunnel maps and 47 cross-sections were used to create the geological models. The Aijala-Metsämonttu volcanogenic massive sulphide ore deposits are in the same stratigraphic zone between the footwall quartz-feldspar-porphyry and hanging wall amphibolite. Sulphide lenses of both deposits are vertically on the south side of the footwall and hanging wall contact. The main host rocks to sulphide ores are skarn and cordierite-gneiss. Several local faults intersect the deposits. The most significant faults displaced overlying blocks to the south in Aijala and to the north in Metsämonttu. The Aijala-Metsämonttu deposit belongs to the Zn-Pb-Cu group. The occurrence style and concentrations of metals vary between deposits. Copper ore is present in Aijala but absent in Metsämonttu, whilst zinc-lead ore is present in Metsämonttu but absent in Aijala. Precious metals occur in both deposits with a companion of base metals. The Metsämonttu deposit is rich in precious metals compared to the Aijala deposit, and the presence of high content of precious metals correlates with the incidence of lead ore. Precious metals concentrations increase from east to west and deeper in Metsämonttu.
  • Jokela, Eetu (2020)
    The Sukseton area is located in the northern part of Kittilä municipality, Central Lapland Greenstone Belt, approximately 15 km N from Suurikuusikko gold mine and 5 km NW from Iso-Kuotko orogenic gold deposit, between several large crustal scale thrust and shear zones. This area is a mix of different volcanic formations of Kittilä suite, felsic intrusion of Vuotso Complex and Paleoproterozoic intrusive rocks in the north. In addition to this, several porphyry dykes cut the Kittilä suite volcanic rocks around the area. Exploration work in this area started in the 1980’s when Outokumpu Oy found two minor gold and gold-copper mineralizations. In 2017, Agnico Eagle Finland Oy continued exploration in this area, intending to define the regional geology and the extent of the mineralizations. As a result of this exploration work, this study investigates more closely the regional geology, geochemistry, metamorphism and structural geology of the Sukseton area, as well as the geochronology of associated porphyry dykes. To understand and define the geology of the area, the following methods were used: geological bedrock and exploration trench mapping, interpretation of drill core loggings and several geophysical surveys, optical studies of polished thin sections and U–Pb dating a porphyry dyke sample. The metamorphic conditions of the area were studied through thorough petrological studies. In addition, an extensive geochemical and geotectonic classification of the rocks in the area was conducted. The Sukseton area composes mainly of different tholeiitic basalts and pyroclastic rocks with minor sulphide rich graphitic volcanic sediment and chert sections. Based on this study, these volcanic rocks originate from island arcs and mid-ocean ridges. With the help of geophysical surveys and field measurements, a couple of large fold structures were identified from the eastern part of the study area as well as a large shear zone in the middle of the area striking NE–SW. Porphyry dykes cut the volcanic rocks all around the area giving the minimum age of 1940±18 Ma for the volcanic rocks. Composition of porphyry dykes vary from rhyolites to basalt and they have similar geochemical characteristics with Nyssäkoski type felsic veins. The peak metamorphic conditions in the area represent high-P amphibolite facies metamorphism. Also, hydrothermal alteration is common in Sukseton and it can be metamorphic and magmatic in origin.