Browsing by master's degree program "Geologian ja geofysiikan maisteriohjelma"

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.

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.

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.

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).

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.

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.

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.

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.

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.

This study consists of a comprehensive characterization of the geology, geochemistry, alteration, and mineralization at the Ronaldo prospect as well as an evaluation of its ore potential. Previous mapping campaigns of the prospect, which lies in the Central Andes in Peru at an elevation of 4300 metres, have identified intrusions overlain by a volcanic package. The intrusions are crosscut by silicified ridges that host epithermal mineralization. Satellite imagery reveals that the topographically elevated areas exhibit strongly altered rocks identified as an advanced argillic-altered lithocap. The methods used to define and better understand the geology and the evolution of the hydrothermal system included reconnaissance field mapping, whole-rock geochemistry, short-wave infrared spectroscopy, petrography, and geochronology. Previous studies have shown that only high-sulfidation epithermal mineralization can be spatially and temporally linked to porphyry Cu mineralization, and therefore this study investigates – among other aspects – what type of epithermal mineralization is present at Ronaldo in order to evaluate the potential for concealed at-depth porphyry Cu mineralization. Two separate lower Miocene intrusive units were identified, a porphyritic diorite and a porphyritic granodiorite, whose average age difference is 1.79 Ma. The intrusive units display intermediate argillic alteration. The overlying extrusive units are Sacsaquero Formation basaltic andesites and ignimbrites that are either unaltered or display propylitic alteration. The basaltic andesite roof pendants observed at Ronaldo indicate that the tops of the intrusions are preserved. At high elevations, advanced argillic alteration composed of pyrophyllite, kaolinite, and dumortierite was observed. This area is the remnant, deeper zone of a larger lithocap. The steeply dipping silicified ridges that display sericitic alteration were inferred to be the root zone of this lithocap. Elevated values of trace elements such as Te, Bi, As, and Sb suggest that the Ronaldo prospect is mostly situated in a sericitic alteration zone related to a porphyry-like magmatic-hydrothermal source located at greater depth. Isolated magnetite aggregates were observed in magmatic-hydrothermal breccia, which indicates that the sericitic alteration may have overprinted potassic alteration. A few intermediate-sulfidation epithermal veins and porphyry-related veins, including a banded molybdenite quartz vein, were observed in the creek near the major fault. At Ronaldo, high silica content and sericitic alteration correlate well with elevated concentrations of Ag, Au, and Mo, whereas Cu concentration does not correlate well with any alteration type or with silica content. Quartz veinlets in the silicified ridges that host abundant Ag and Au mineralization were interpreted to have formed at a slightly later stage and to be unrelated to the magmatic-hydrothermal system. This mineralization was interpreted to be low-sulfidation epithermal in origin due to features such as abundant adularia, lattice-textured bladed calcite replaced by quartz, crustiform banding, banded quartz-chalcedony veins, druse-lined cavities, and high Ag/Au ratios. In conclusion, the Ronaldo prospect comprises a hydrothermal system in which the deep, root zone of an advanced argillic lithocap is exposed. The exploration potential for low-sulfidation epithermal mineralization in the silicified ridges is rather significant, whereas the potential for porphyry Cu mineralization is minor due to the lack of appreciable Cu and Mo mineralization, typically shallow-depth porphyry-related hydrothermal alteration, and the lack of high-sulfidation epithermal mineralization.