Browsing by discipline "Geologi"
Now showing items 41-60 of 109
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Itämeren ja Mustameren geologinen historia, sedimentaation kehitys sekä ympäristöongelmien vertailu (2014)The study area includes the Baltic and the Black Sea and their catchment basins based on mainly recent literature. The purpose of this study is to clarify environmental problems of these seas and the effect of geologic history and other factors of basins. The early geologic history of the Baltic Sea and the Black Sea basins differ from each other. The Baltic Sea basin (~2,5 Ga BP) is clearly older than the Black Sea basin (~299 Ma BP) and formation processes of these two basins are not related to each other directly. The Quaternary glaciations were intensive in the whole Baltic basin, whereas in the Black Sea only the highest and some northernmost areas of the basin were covered by ice sheet. The last connection between sea and these two basins have occurred almost at the same time, which is in the Baltic Sea ~8,5–6,5 ka BP and in the Black Sea ~9,4–8,4 ka BP. The most significant environmental problems in the Baltic and Black Sea are eutrophication, overfishing, non-indigenous species, heavy metals and hazardous substances. In general anthropogenic forcing is greater in the Baltic Sea than in the Black Sea leading changes in an ecosystem. The inflow of nutrients and pollutions occurs especially in to the northwest region of the Black Sea where large rivers (Danube and Dnieper) flows. On the contrary the eutrophication is wide and occurs almost in the whole basin of the Baltic Sea. It may take decades before the effect of reduced nutrients and the recovery of marine ecosystem occur in the basin. There are no significant heavy metals or hazardous substances contamination observed in the both sea basins. The results indicate that the overfishing and the spreading of non-indigenous species have caused more damages in the Black Sea than in the Baltic Sea. There have formed several environmental conventions both in the Baltic Sea and in the Black Sea which are emphasized especially in the Baltic Sea because of actions of EU. The effect of EU will probably increase in the Black Sea in future because new member countries such as Bulgaria and Romania and candidate country Turkey are surrounding by the Black Sea.
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(2013)Observations of the highest shoreline of the Baltic Sea have been collected over decades but only recently it has been possible to create an ArcGIS based database that covers whole Finland. An ancient shoreline database (ASD) was created in this study, in which shoreline observations from earlier publications were collected and analysed. The map was created in two resolutions (10 and 25 m) using TIN (Triangulated Irregular network) as an interpolation method. The highest shoreline of the Baltic Sea basin designates the post-glacial shoreline level that separates sub- and supra-aquatic areas. The highest shoreline is diachronous and shorelines have formed during various stages of the Baltic Sea, i.e. from the Baltic Ice Lake to the Ancylus Lake between 12 000-8500 BP. Shoreline landforms that can be connected to the highest shoreline are washed hillsides, deltas, stone belts, esker tops, cliffs, beach terraces, beach ridges and lake ramparts. Shoreline observations were collected in ASD as point type data, in which every observation has location, altitude and other related information. Three different DEMs (Digital Elevation Model) were used to measure altitudes. Two of them, DEM 10 m and DEM 25 m cover whole area of Finland and along with them were used LiDAR DEM, which only covers those parts of Finland that were published in 2011 or earlier. DEM 25 m has resolution 25 meters and it has been used to measure the altitude of shorelines in areas where LiDAR DEM is not available. DEM 10 m is newer DEM with 10 meter resolution and it is only used at the end of the database collecting. New shoreline observations were also scouted using MDOW hillshade and LiDAR DEM. A total of 935 highest shoreline observations were collected in the ASD and 69 dummies were defined, which were used to backfill missing areas outside the ASD. Best shoreline observations were used to interpolate a surface that represents the highest shoreline using TIN-model. The TIN-surface was subtracted from DEM 10 m and DEM 25 m that were converted into rasters and result maps were two different resolution raster maps, which were converted to polygons. The observations of the Baltic Ice Lake, the Yoldia Sea and the Ancylus Lake were used in same interpolation regardless the fact that the level of the Baltic Ice Lake dropped 28–25 meters at around 11 600 BP. Result maps largely correspond with the map of Eronen and Haila that were published in 1992. The map based on DEM 10 m has clearly better resolution and it gives new information of the border of the sub- and supra-aquatic areas in Finland. DEM 25 m is mainly beneficial in large scale because it is coarser than DEM 10 m. TIN-model interpolates the drop of The Baltic Ice Lake well enough but additional shoreline observations would be needed for more precise outcome. The highest shoreline of the Baltic Ice Lake district in this study is 163 m a.s.l. close to the First Salpausselkä in the vicinity of Hollola and the highest shoreline of the Ancylus Lake is located in the city of Rovaniemi where it reaches 220 m a.s.l.
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(2013)Itä-Suomen arkeeinen alue koostuu laajoista migmatiitti-granitoidialueista sekä niiden sisäisistä vihreäkivivyöhykkeistä ja kiilleliuske-paragneissialueista. Vihreäkivet ovat potentiaalisia Ni-Cu-PGE-esiintymien isäntäkiviä. Varsinaisten vihreäkivivyöhykkeiden ulkopuolella on pienempiä ultramafisia alueita. Lieksan Tainiovaaran pieni nikkeliesiintymä on osoitus, että Ni-Cu-PGE-mineralisaatioita voi muodostua myös näille pienemmille ultramafisille alueille. Tutkimuskohteina on 21 pientä ultramafista aluetta Itä-Suomesta. Alueet ovat MgO-, Al2O3- ja TiO2-pitoisuuksien ja REE-pitoisuuksien perusteella luonteeltaan komatiittisia lukuun ottamatta Suolameren kohdetta. Suurin osa kohteista edustaa alumiinin suhteen köyhtymättömiä Munro-tyypin komatiitteja. Jamalin, Louhimon ja Näätävaaran kohteet edustavat mahdollisesti Al-köyhtyneitä Barberton-tyypin komatiitteja. Merkittävimmät muuttumisilmiöt tutkimuskohteilla ovat hydraatio ja karbonaattiutuminen. Tyypillinen mineraaliseurue on serpentiini + tremoliitti + kloriitti + oliviini + karbonaatti + talkki. Tyypillinen malmimineraaliseurue on Cr-pitoinen magnetiitti + pentlandiitti + magneettikiisu + kuparikiisu. Muuttumatonta kromiittia ei tavattu kivissä, mikä viittaa vähintään keskiasteen amfiboliittifasieksen metamorfoosiin. Tutkimuskohteiden geokemia eroaa Tainiovaarasta ainoastaan alemmilla Ni-, Cu- ja PGE-pitoisuuksilla. Tainiovaaran mineralogia on hyvin serpentiini- ja karbonaattivaltainen. Tremoliitin ja oliviin puute viittaavat tutkimuskohteita alhaisempaan vihreäliuskefasiek-sen metamorfoosiin, mutta kromiittien voimakas muuttuminen viittaa amfiboliittifasieksen metamorfoosiin. Tutkimuskohteet ovat metamorfoituneet spinellikoostumusten ja mineralogian perusteella vähintään keskiasteen amfiboliittiasteen oloissa. Suolameren kohde poikkeaa geokemialtaan ja mineralogialtaan muista tutkimuskohteista eikä sille ole suoraa vertailukohtaa Itä-Suomen arkeeiselta alueelta. Suolameri on rikastunut LREE:n ja Pd-ryhmän alkuaineiden sekä kuparin suhteen. Kohteen geologi-nen luonne liittyy luultavasti jollain tavalla sitä ympäröivään Koitereen sanukitoidiin. Kairatuista kohteista merkittävää malmipotentiaalia osoittavat Jonkerin ja etenkin Jamalin kohde. Sekä Jamalin että Jonkerin kohteilta useita näytteitä sijoittuu Ni-Cr-kuvaajassa malmipotentiaaliseen oliviinikumulaattikenttään. Jamalin malmipotentiaalia tukevat lisäksi MgO-rikkaat kivet, Ni/Cr-, Cu/Zn-suhteet ja niiden yhdistelmä Kambalda-suhde sekä Eu-anomaliat osassa näytteistä. Ei-kairatuista kohteista lupaavimpia ovat Karhivaaran ja Jänisahon kohteet. Ne osuvat molemmat Ni-Cr-kuvaajassa malmipotentiaaliseen oliviinikumulaattikenttään. Jänisahon malmipotentiaalisuutta tukevat myös Eu-anomalia REE-kuvaajassa sekä MgO-pitoiset spinellit.
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(2013)The Kedonojankulma Cu-Au occurrence is situated in the Svecofennian Häme belt in Southern Finland, about 13 km north of Forssa. The occurrence is hosted by a porphyritic tonalite intrusion. The surrounding of tonalite intrusion consist mostly Palaeoproterozoic mafic and intermediate volcanic rocks. The occurrence was found by Geological Survey of Finland in 2006 after regional till-geochemical surveys and diamond drillings. Several features that are typical in most porphyry copper deposits have been identified, such as metal content and metals zoning. Only a few porphyry copper deposits have been found from the Palaeoproterozoic granitoids in the Fennoscandian Shield area. Aim of this study is to exanimate fluid inclusions and determinate is there indication of porphyry copper-type deposit. In many parts of the Kedonojankulma intrusion, early dark quartz-sulfide veins are cutting the host rock. The highest metal grades are in and around quartz-sulfide veins. The samples for laboratory measurements were collected from these dark quartz-sulfide veins. The most important research method was microthermometric studies. Daughter minerals in fluid inclusion were also identified by scanning electron microscope-energy dispersive spectrometry (SEM-EDS). Based on the microthermometric data from four samples, fluid inclusions show a wide variation in salinity about 2 - 45 wt. percent (NaCl equiv.) and homogenization temperatures about 100 - 420 °C. The most common ore minerals were found in porphyritic tonalite as well as daughter minerals inside the fluid inclusions. Evidence of boiling was also observed in a few samples. Fluid inclusion compositions, salinity, daughter minerals, boiling, a magmatic origin of fluids, homogenization behavior and many other factors indicate a porphyry copper-type deposit.
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(2016)Saline groundwaters in crystalline bedrock may contain significant amounts of gases, most commonly methane, nitrogen, hydrogen and helium. Under normal atmospheric conditions the solubility of gases in water is much lower than deeper in the crust where pressure, temperature and salinity of the water affect the solubility. Gases behave differently as free gas as when dissolved in water. For that reason it is important to find out the state of the gases when examining for example the origin or age of the groundwater. Solubilities of gases in water at different conditions are studied here with physical chemistry, semiempirical models and gas solubility literature. Maximum solubilities for methane, nitrogen, hydrogen and helium are determined for 273-323 K temperature, 1-300 bar pressure and 0-2 molal concentration salinities. The solubility of gases increases most when the pressure is increased. Increase in the salinity of the water usually decreases solubility, similarly increase in temperature usually decreases solubility. The study of solubilities is also applied to the conditions of the 2,5 km deep Outokumpu Deep Drill Hole and samples obtained from it during 2011-2012. The gas samples have been collected with pressurized techniques that preserve the sampling depth in situ -pressure in the samples until they are released for the analysis in the laboratory. This way accurate data of the gas amounts at certain depth is obtained, allowing reliable quantitative study of the gases and their solubilities. In the Outokumpu Deep Drill Hole methane and nitrogen are the most represented gases. In the deepest part hydrogen is the dominating gas. The greatest amount of gases is observed at a depth of 970 m. In all sampling depths (180, 500, 970, 1470, 1820, 2350 and 2480 meters) all the gases seem to be dissolved in water. In sampling depth 180 m the sum of the partial pressures of the gases (ca. 13 bar) is approaching the existing hydrostatic pressure (ca. 18 bar). The depth where gas bubbles escape from the solution and form a separate gas phase is likely 150 meters and above. Deeper in the drill hole the effect of pressure is so significant that all the gases are most likely dissolved in water at depths under 180 meters.
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(2012)Suomessa pohjaveden tavallisimmat laatuongelmat ovat kohonneet rauta- ja mangaanipitoisuudet sekä alhainen pH-arvo. Kalkkikivialkaloinnin on käytännössä todettu parantavan veden laatua, ja menetelmää on tutkittu useasti vesilaitoksilla ja laboratorioissa toteutetuin kokein. Yksityiskaivoissakin kalkkikivialkaloinnin on käytännössä todettu parantavan vedenlaatua, mutta tutkimuksia esimerkiksi menetelmälle parhaiten soveltuvista kohteista ei ole tehty. Tämän tutkimuksen tarkoituksena on selvittää alustavasti millaisissa tapauksissa kalkkikivialkalointi tietyllä mitoituksella on toimiva kunnostusmenetelmä ja mitkä asiat tähän voi vaikuttaa. Koska Suomessa pohjavesi on luonnostaan pehmeää, lievästi hapanta, rauta- sekä mangaanipitoista ja oman kaivon varassa olevia talouksia on paljon, tehokkaalle ja turvalliselle veden käsittelymenetelmälle on kysyntää edellä mainittujen laatuongelmien korjaamiseksi. Kaivoon sijoitetun kalkkikivirouheen vaikutusta veden laatuun tarkastellaan yleisellä tasolla vuosina 2003–2011 raportoitujen kunnostuskohteiden vesianalyysitietojen perusteella. Kaivokohtaisesti kalkkikivialkaloinnin vaikutusta tutkitaan kolmentoista yksityisen rengaskaivon avulla analysoimalla niiden vesinäytteitä ennen ja jälkeen kalkkikivikunnostuksen. Tutkimuskaivojen veden kemiallista laatua tutkitaan in situ –menetelmin ja laboratorioanalyysien avulla vuoden ajan. Kaivovesistä tutkitaan pH, sähkönjohtavuus, alkaliteetti, pääionit sekä happi-, hiilidioksidi-, rauta- ja mangaanipitoisuudet. Kunnostuksen vaikutusta veden kalkkikivikylläisyyteen tarkastellaan mallintamalla kalkkikiven ja veden välisiä reaktioita hydrogeokemiallista mallinnusohjelmaa (PhreeqC) käyttäen. Laajemman aineiston perusteella kalkkikivikunnostus paransi kaivoveden laatua tilastollisesti merkitsevästi liian alhaisen pH-arvon sekä nitraattipitoisuuden osalta. Kolmestatoista tutkimuskaivosta kahdeksassa tapahtui lähtöoletusten mukaisia muutoksia eli veden pH-arvo, alkaliteetti, sähkönjohtavuusarvo sekä kalsium- ja magnesiumpitoisuudet nousivat. Kaikkien 13 tutkimuskaivon vedet tulivat kalsiittikylläisemmäksi kalkkikivikäsittelyn jälkeen, ja vain kolmessa kaivossa vesi ei saavuttanut kalsiittikylläisyyttä koko seurantajakson aikana. Kaivonomistajille lähetetyn kyselyn perusteella suurin osa oli huomannut kaivossaan kaivoveden laadun ja/tai määrän parantumista kalkkikivikunnostuksen jälkeen. Kalkkikivialkalointia tulisi tutkia mahdollisimman luonnonmukaisissa olosuhteissa (in situ), jotta tuloksien perusteella voitaisiin antaa suosituksia kalkkikivirouheen mitoituksesta yksityisiin talouskaivoihin sekä sopivista käyttökohteista. Lisätutkimuksia tarvitaan menetelmän soveltumisesta eri muodostumatyyppiä edustavalle, eri syvyisille ja erilaisilla kulutuksilla sekä ennen muuta erilaisia raakavesiä edustaville kaivoille. Tutkimuksessa tulee kiinnittää huomiota in situ –menetelmiin sekä vesinäytteiden kestävöintiin. Tutkittaessa kalkkikivialkaloinnin soveltuvuutta raudan ja mangaanin poistamiseen talousvesikaivoissa on orgaanisen aineksen ja mikrobitoiminnan vaikutus prosessiin otettava huomioon.
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(2015)The purpose of rock mass classification is to get to know the major features affecting the rock and to divide the rock mass in to parts that behave the same way. RG-classification is a Finnish qualitative rock mass classification that describes the rock mass objectively. Another commonly used classification is Q-system, which gives numerical values for the classified rock. ISO (the International Organization for Standardization) is a worldwide federation of national standard bodies, which has published a standard ISO 14689-1 for identification and classification of rock for ground- and water construction. The Finnish Standards Association SFS has approved the aforesaid for international standard SFS-EN ISO 14689-1. In this thesis I use the name ISO-classification for identification and classification of rock according to this standard. The purpose of the study is to compare the ISO-classification system to the rock classification systems used in Finland, especially to the commonly used RG- and Q-classifications. The main focus of this study is the Tampere Rantatunneli where Q- and RG-classification systems are systematically used. The ISO-classification is divided in to three parts: the identification of the rock and the descriptions of rock material and rock mass. To help the testing of classification a mapping form has been developed to take the parameters above into account. Q-parameters have also been considered in the form and the possibility of exploiting the ISO-parameters in defining the Q-system was also tested. The mapping according to the ISO-classification was performed in five different tunnel breaks in Tampere Rantatunneli. These mapping areas A, B, C, D and E are located in Näsinkallio and Naistenlahti areas. Three main joint directions were found in each five tunnel breaks with one of them parallel to schistosity. The main rock type in each tunnel break was micagneiss classified as very hard (100-250 MPa). RG- and ISO-classifications are both descriptive methods that describe the rock and do not provide a quantitative result of the rock quality. However, the ISO-classification is more precise than the RG-classification. Using the ISO-classification in Finland requires that some of the measuring parameters are either partly or totally modified or that categories are combined together. It is possible to derive parameters from ISO-classification to be used as Q-classification parameters.
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(2017)The layman’s sample practice of the Geological Survey of Finland (GTK) is a unique national practice in raw material exploration and research. Its main purpose is to increase knowledge related to Finnish raw material resources. The operation is quite rare on a global scale. A layman’s sample (kansannäyte) is a sample of rock, mineral, or soil sent to a geologist or other type of expert by a rock hobbyist. The Layman’s Sample Office of the Geological Survey of Finland (GTK) receives thousands of samples from all over Finland every year. The office handles ore samples, industrial minerals, dimensional stone, precious stone and gemstone discoveries, and metals of technological interest. The concept of layman’s sample reflects the action of its history and original purpose. The practice started in the 18th century and has continued uninterrupted since then. Thirtytwo of the metallic mines in Finland have been discovered on the basis of a layman's sample. Currently, further new mining operations, on which the first reference sample has been sent by the public, are being launched. In addition to the economic benefit, the practice also has other tasks. The sample office answers geology-related questions sent in by the general public and provides competent and up-to-date information on the importance of raw materials to the society. The challenge in the future is to improve the quality of the samples. Also in the future, the development of digital applications will be important including web and mobile applications, for example teaching map services and platforms. The new applications could also inspire young people to the rock hobby in general as well as increase the geological knowledge of the general public. The digital archive of layman’s samples contains information on more than 60 000 bedrock and boulder samples. Layman’s samples and metallogenic zones can be compared with each other. Geologically ore potential zones could be identified and sampled. The archive also reveals new areas with ore potential.
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(2014)The 2020 climate and energy package is obligatory for the EU to increase renewable energy usage. Because of this and a trend of increasing energy prices, Finland has started to develop geothermal energy more since the year 2000. Geothermal energy is heating- and cooling energy which comes from the bedrock, earths surface layers, water systems and from surface sediments in water systems. This research is about geothermal energy, particularly groundwaters potential to make energy for heating and cooling in two different cities in Finland. Generally research assumes that urbanization and the 'heat island' phenomenom makes groundwater warmer. This groundwater research was carried out in Lohja and Turku. There were altogether eight groundwater pipes and the groundwater temperatures were followed for 5,5 months. Two of these groundwater pipes were located in natural areas just outside of the city, temperatures of the natural area groundwater pipes were used to compare the results from the city groundwater pipes. 58 Thermochron dataloggers were installed to the groundwater pipes and they measured the temperatures every two hours from different depths. In addition there was one Thermochron datalogger in each city which took measurements of the outside temperatures. Thermochron dataloggers haven't been used for measuring groundwater temperatures over a long period of time, so it was uncertain how or if this method would succeed. Due to this untried method of research, the dataloggers were checked approximately once a month and the data extracted from them thus far. Temperature depth profiles were made from groundwater temperature results, and the possible groundwater energy results were calculated from these. Temperature results showed that urban groundwater is warmer than the natural groundwater. Natural groundwater temperatures were approximately +5.5 – 6.5 °C and +7 – 13 °C in urban areas. Results also showed a time delay between the groundwater temperatures and the air temperatures. Air temperatures decrease quite steadily from July's +18.5 °C to December's +0.5 °C. The highest temperatures of the groundwater were recorded between October and November. Thermochron dataloggers worked variably in the groundwater pipes due to the subjection of high pressures along with the lack of water resistance. Some of these dataloggers ceased to work in the midst of the research, and as a consequence results of the temperatures had to be partly interpolated. To obtain a better energy potential, the groundwater temperature should be researched for a longer period of time than 5,5 moths, thus producing a comprehensive set of results throughout the seasons bearing a strong correlation. Under the circumstances these results shows groundwater energy is viable in the local areas.
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(Helsingin yliopistoHelsingfors universitetUniversity of Helsinki, 2012)Keski-Pohjanmaan Kaustisen-Ullavan alueella on yli 400 km2:n laajuinen pegmatiittikenttä, josta on tähän mennessä löydetty 16 spodumeenipitoista pegmatiittiesiintymää. Tutkielmassa vertaillaan Heikinkankaan, Leviäkankaan, Läntän, Outoveden, Päivänevan ja Syväjärven pegmatiittiesiintymien sekä alueen granitoidien geokemiaa. Kaustisen-Ullavan alue kuuluu Keski- ja Länsi-Suomen paleoproterotsooiseen, 1.95 1.89 Ga ikäiseen svekofenniseen saarikaarikompleksiin, joka sijaitsee Fennoskandian kilven keskiosissa. Alueen geologiset pääyksiköt koostuvat Keski-Suomen granitoidikompleksin reunaosista sekä tätä ympäröivästä Pohjanmaan liuskevyöhykkeestä, jota noin 1.79 Ga ikäiset spodumeenipegmatiittijuonet leikkaavat. Pegmatiittien päämineraalit ovat spodumeeni, albiitti, kalimaasälpä, kvartsi ja muskoviitti. Suurempien esiintymien pääjuonet ovat 200 500 m pitkiä ja leveimmillään 25 m. Esiintymät luokitellaan petrogeneettisessä luokittelussa LCT- eli Li-, Cs- ja Ta-rikastuneeseen orogeeniseen pegmatiittiperheeseen sekä geologisessa luokittelussa rare element- eli harvinaisten alkuaineiden REL-pegmatiittiluokkaan ja sisäiseltä rakenteeltaan suhteellisen homogeeniseen albiittispodumeenityyppiin. Pegmatiitit ovat koostumuksiltaan peralumiinisia ja graniittisia. Esiintymien keskimääräiset Li2O-pitoisuudet ovat 0.68-1.07 %, jotka vastaavat noin 9.7-15.5 %:n spodumeenipitoisuuksia. Tärkeimpien hivenalkuaineiden pitoisuudet vaihtelevat tutkituissa esiintymissä seuraavasti: Rb = 330−860 ppm, Cs = 49−57 ppm, Be = 50−124 ppm, Ta = 17−89 ppm ja Nb = 20−84 ppm. Esiintymissä on selkeitä systemaattisia eroja differentiaatioasteen mittareissa, kuten K/Rb-, Sr/Rb-, K/Cs-, Nb/Ta-, Fe/Mn- ja Al/Ga-suhteissa, joiden perusteella Outoveden ja Läntän esiintymät ovat vertailluista esiintymistä kemiallisesti kehittyneimpiä ja Syväjärven ja Heikinkankaan esiintymät vähiten kehittyneitä. Leviäkankaan ja Päivänevan esiintymät asettuvat geokemiallisessa vertailussa näiden esiintymien välille. Globaalissa geokemiallisessa vertailussa esiintymät ovat koostumukseltaan tyypillisiä albiittispodumeenityypin pegmatiitteja. Alueellisessa vertailussa pegmatiiteissä ei näy merkkejä systemaattisesta koostumusvaihtelusta. Myös pegmatiittien sisäinen koostumusvaihtelu on pääosin epäsystemaattista, mutta Outoveden pegmatiittien muskoviitti- ja spodumeenipitoisissa osissa on systemaattisia eroja K2O-, Rb-, Nb- ja Ta-pitoisuuksissa. Outoveden juonten muskoviittipegmatiiteiksi muuttuneet reunaosat saattavat viitata teksturaaliseen kompleksisuuteen , jollaista ei muissa esiintymissä ole. Koostumuksensa, rakenteensa, kokonsa ja sijaintinsa perusteella kaikkein todennäköisin pegmatiittien lähdegranitoidi on pegmatiiteista etelässä sijaitseva Kaustisen pegmatiittigraniitti, jonka ikää ei tunneta. Pegmatiittiesiintymien keskimääräiset litiumpitoisuudet vaikuttavat kasvavan Kaustisen pegmatiittigraniitista etäännyttäessä, millä saattaa olla merkitystä malmietsinnän kannalta. Läntän pegmatiitit saattavat sijaintinsa ja geokemiallisten piirteiden (korkea TiO2-pitoisuus, alhainen P2O5-pitoisuus, korkea Nb/Ta-suhde sekä alhaiset Al/Ga- ja A/CNKL-suhteet) perusteella olla osa erillistä pegmatiittiryhmää erotuksena viiden muun esiintymän muodostamasta Kaustisen pegmatiittiryhmästä.
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(2016)The Karoo large igneous province is situated in southern Africa, Antarctica and Falkland islands and its formation has been connected to the break-up of Gondwana supercontinent. According to previous studies the formation of the Karoo LIP happened during a short period of time, ca. 182 Ma. There have been found also older volcanic rocks from Antarctica (ca. 189 Ma). In this study the felsic volcanic rocks from central Mosambique were dated using the U-Pb zircon method. Zircons from four samples were analyzed using Secondary Ion Mass Spectrometry. The weighted U-Pb ages of the samples are between 182-186 Ma and it was possible to distinguish zircon populations of different ages. The ages of the populations were ca.189–190 Ma, ca. 184–185 Ma and ca. 181–182 Ma. There were also inherited zircons in two samples (385–903 Ma, 2680–2760 Ma and 1950–2450 Ma). From the age results it is possible to conclude that at ca. 188–189 Ma there was crystallizing melt in the magma chamber. At ca. 184–185 Ma and ca. 181–182 Ma more melt was separated from the crystal mush. Of the same samples Lu-Hf isotope composition was also analyzed using Laser Ablation Inductively Couples Mass Spectrometry. From the εHf values of the samples it is possible to conclude that the parental material of the felsic volcanic rocks of central Mozambique was a partial melt of the felsic crust rather than fractional crystallization of Karoo basalts.
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(2015)Hampaat kuluvat käytössä. Kuluminen johtuu ruoassa olevista sekä sen ulkopuolelta tulevista partikkeleista. Erilaiset partikkelit aiheuttavat erilaista kulumista. Mikrokulumisjälkien analyysiä voidaan käyttää kulumisen kvantifioimiseen. Analyysimenetelmässä lasketaan hampaan pinnalta mikroskooppisia naarmuja ja kuoppia sekä niiden kokoja. Erot kulumisjäljissä kertovat erilaisten ruokavalioiden suosimisesta. Heinänsyöjillä hampaan pintaan tulee enemmän naarmuja, kun taas lehtien ja muiden kasvinosien syöjille muodostuu enemmän kuoppia. Maa-aines ja kasvien fytoliitit on jo pitkään nimetty pääasiallisiksi kulutusta aikaansaavat tekijöiksi. Muita vaihtoehtoja ovat esimerkiksi kuidut, kovat ruoat ja hampaiden keskinäinen hankaus eli attritio. Mikrokulumisjälkien syntyä oikeissa hampaissa ei ole tarkasteltu kokeellisesti. Havainnoivan tarkastelun on aika saada rinnalleen kokeellisesti tuotettua tietoa. Tässä kokeessa hevosen hampaita laitettiin pureskelemaan erilaisia ruokavalioita. Ruokavalioita olivat sinimailanen (L=lucerne), heinä (G=grass), heinä-riisi (GR=grass-rice) ja heinä-riisi-hiekka (GRS=grass-rice-sand). Ruokavalioissa oli edeltävässä järjestyksessä kasvava kuluttavien ainesosien määrä ADIA (Acid Detergent Insoluble Ash), joka L:n, G:n ja GR:n tapauksessa oli myös kasvava fytoliittipitoisuus. Lisäksi yksi ryhmä koostui hampaista, jotka pureskelivat pelkässä vedessä ilman ruokaa (ATTR). Jokainen kahdestakymmenestäviidestä hammasparista pureskeli ruokaa 6 h 30 min, joka vastaa noin 100 000 purentaa tai noin seitsemää päivää oikean hevosen elämässä. Pureskelun jälkeen hampaiden pinnoista tehtiin epoksivalokset, joista otettiin kuvat stereomikroskoopilla. Kuvat otettiin kahdesta kohtaa hampaan keskellä olevasta kiillenauhasta. Kiillenauhoista laskettiin 0,4 x 0,4 mm kokoiselta alueelta kaikki naarmut ja kuopat Microware 4.02 -ohjelmalla. Tulokset osoittivat, että ATTR ja GRS eroavat hiekattomista ruokavalioista. ATTR synnytti paljon pieniä kuoppia ja vain vähän naarmuja. Attritiohampaat olivat myös aivan erinäköisiä kuin ruokavalioita pureskelleet hampaat. GRS:ssä oli voimakas negatiivinen korrelaatio kuoppien määrän ja naarmujen määrän välillä. G:n ja GR:n pystyi erottamaan toisistaan tilastollisesti merkittävästi isojen kuoppien, jälkien pituuden, jälkien pituuden ja leveyden suhteen, kuoppien prosenttiosuuden sekä ohuiden naarmujen prosenttiosuuden suhteen. L:llää ei voinut erottaa tilastollisesti merkittävästi G:stä tai GR:stä tässä kokeessa mitatuilla ominaisuuksilla. Mikrokulumisjälkien tutkiminen ei anna täydellistä vastausta, mutta se kertoo karkeasti minkälaista ruokavaliota eläin on syönyt. Kaikki ruokavaliot ja attritio aiheuttivat mikrokulumiskuvioita kiilteeseen. G:n ja GR:n välillä oli selviä eroja, mutta L oli aina niiden välissä. Tilastollisesti havaittavia tuloksia olisi mahdollisesti saanut enemmän, jos koeasetelmia olisi muuttanut tai näytemäärät olisivat olleet suurempia. Erot G:n ja GR:n välillä voidaan mahdollisesti selittää eri fytoliittimäärillä. GR:n suurempi fytoliittimäärä kuluttaa nopeammin kiilteen pintaa, ja hävittää jo olemassa olevia jälkiä. GRS:n suuri vaihtelu voidaan selittää sen komponenteilla. Riisi ja heinä aiheuttavat ohuita naarmuja, kun taas hiekanjyvät tuhoavat niitä aiheuttamalla isoja kuoppia ja leveitä naarmuja. Tällaistä hiekansyömistä tapahtuu kuitenkin vain hyvin äärimmäisissä tapauksissa oikeassa elämässä. Tulevissa tutkimuksissa tulisi testata raekooltaan paljon pienempää mineraalipölyä. Tulokset paljastivat, että L, jossa ei ollut ulkoista maa-ainesta ja vain vähän fytoliittejä, aiheutti samanlaista kulumista kuin G ja GR. Kuidut tai muut ainesosat kasveissa aiheuttavat mahdollisesti mikroskooppisia kulumisjälkiä kiilteeseen.
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(2018)Kurikan alueella esiintyy geologialtaan Suomen oloissa ainutlaatuinen ja rakenteeltaan monimuotoinen monikerroksinen paineellinen akviferisysteemi. Rakenteen kompleksisuuden mahdollistaa Kurikan alueella kallioperän topografian suurehkot vaihtelut ja sen päälle jääkausiajan prosesseissa kerääntynyt paikoin jopa yli 100 metriä paksu maapeite. Tämä maanpeite pitää sisällään paikoin 2–3 toistensa päällä sijaitsevaa akviferia. Kurikan pohjavesiesiintymää on tutkittu GTK:n, Vaasan vesihuollon ja Kurikan Vesi Oy:n toimesta jo useita vuosia. Tavoitteena on hyödyntää alueen pohjavettä Vaasan ja Kurikan kuntien tarpeeseen, sekä turvata Pohjanmaan alueella laajemminkin vesihuoltoa. Paineellinen akviferi aiheuttaa usein runsasta lähteisyyttä. Pohjaveden purkautumiskohteita tutkittiin tässä työssä vesinäytteistä analysoidun hydrogeokemian (pääionijakauma, liuennut silikaatti, alkaliteetti, sähkönjohtavuus sekä vedyn ja hapen stabiilien isotooppien koostumus) ja ilmasta käsin suoritetuin termisten kuvausmenetelmien avulla (TIR). Lämpökuvia tuotettiin UAV (Unmanned Aerial Vehicle) lentoalustalla sekä helikopterista käsin. UAV:n tuottamia lämpökuvia käsiteltiin Pix4D-ohjelmalla, jolloin niistä saatiin georeferoituja kuvia paikkatietojärjestelmään yhteensopiviksi. Tarkoituksena oli myös alueelta GTK:n toimesta tehtyjen tutkimusten ja saatavilla olevan geologisen tiedon avulla selvittää tämän paineellisen pohjavesisysteemin luonnetta ja rakennetta. Tähän kuului pohjaveden muodostumisalueiden määrittäminen, pohjavesien kulkeutumisen selvittäminen ja pohjavesien ikien ja laadun arviointi. Kurikkalainen syväpohjavesi löytyy tutkimusalueelta kahden laaksoalueen, Häjyluoma ja Paloluoma, alla sijaitsevasta syvästä akviferista, jotka sijaitsevat kallioperän vanhassa ruhjevyöhykkeessä. Vesi kulkeutuu akviferisysteemiin ympäröiviltä yläviltä alueilta melko suuren korkeuseron saattelemana. Pohjavesi vaikuttaa puhkovan tiensä läpi syvemmältä kohti maanpintaa ja sekoittuvan ylempänä maaperässä sijaitsevan akviferin veteen. Lämpötila-anomalioiden runsain esiintyvyys voidaan yhdistää laaksoalueiden syvien akviferien päälle. Iältään vedet vaikuttaisivat olevan vain muutamia kymmeniä vuosia vanhoja. Kurikan maaperässä näyttäisi olevan runsaasti potentiaalia pohjaveden hyötykäyttöä ajatellen.
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Kuvantamis- ja mallinnusmenetelmien hyödyntäminen kallioperän rakennetutkimuksessa Kuopion alueella (2017)Scientists have developed new research methods for structural geology analysis. By using airborne laser scanning data or imaging, and description of outcrops using stereo photogrammetry technology, we can make very exact structural analysis. Bedrock structure modeling offers new ways to study the bedrock structures. Due to complexity of the bedrock of the Kuopio area it was chosen to a research area. Airborne laser scanning descriptions and structural models was carried out in the Hirvo, Kurkimäki, Paavola and Poroharju study regions. A stereo photogrammetry measurement was executed in the Pieni neulamäki area. The target is to estimate the suitability of methods for structure geology surveys and evaluate their reliability. In particular, the methods of stereo photography gave surprisingly accurate results that can easily use for the data collection and the preservation of data. The Laser scanning models still require further development, so that it can be supported the bedrock surveys.
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(2016)The aeolian silty deposits found in Lammi region are commonly known as Lammi Loess. The term is established even though there are no extensive research done with modern sedimentological methods and some of the previous research on the topic are questioning the completely aeolian nature of these deposits. The purpose of this research was to determine how silty deposits known as Lammi loess fit into the definitions of loess, what type of surface textures can be detected from the deposits grains and in what extent and manner Lammi loess occurs in the Lammi region. The loess deposits of Lammi were studied using field observations and grain size analyses. The sediments grain surface textures were analyzed using scanning electron microscope (SEM). The aim of this study was to achieve an extensive understanding of the deposits properties and occurrences in the Lammi region, and also of the typical surface textures of the grains. 18 sediment samples from ten different locations in Lammi was used as material for the study. In addition one dune sample was used as a point of comparison. The locations were situated at 117-166 m asl. (meters above sea level) and majority of them were located mainly below the highest shore of the Baltic Ice Lake (162 m asl.). Lammi loess is moderately sorted aeolian deposit, consisting mainly of coarse silt and fine sand. The deposits were formed when sediments uncovered by the drop of waterlevel in the Baltic basin were exposed to aeolian activity. The source material of these deposits are local and deposition occurred rather quickly. Lammi loess occurs as rather small and local deposits on the slopes of deltas and hills. The formations are more focused on the north-west slopes. Lammi loess has several characteristics typical for loass, but as a whole it is very individualistic formation with properties that are between loess and coversands. The Lammi loess deposits resemble loess in regards of their texture, color, porosity and skewness, but the distribution of sand sized grains matches that of coversands. Some of the studied sediments were either completely or partially deposited in water.
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(2014)Recent climate related changes in the Arctic have risen concern and interest to better understand the mechamisms of arctic climate system and to predict the future response. Due to short instrumental monitoring a palaeoenvironmental view is required to reveal and understand long-term changes, yet high-resolution palaeoecological and -climatological studies are sparse. Bjørnøya, the Bear Island, (74°30' N, 19° E) is a key site for terrestrial palaeoclimate records along the heat transport system of the North Atlantic Current, with the possibility of linking records from northern Fennoscandia and Arctic Svalbard. A summer temperature series for the past ca. 1000 years was reconstructed from a 64 cm surface sediment core from lake Ellasjøen, SW Bjørnøya, based on quantitative palaeoenvironmental modelling of subfossilized chironomid assemblages. Quality of reconstructions was assessed with modern analogue technique and principal component analysis. To support the interpretation and receive a more holistic view of the lake history, in- lake processes, catchment interaction and factors behind the changes, a multi-proxy approach was chosen. Sediment physical characteristics: water content, loss-on-ignition, magnetic susceptibility and spectrocolorimetric identification of sedimentary signatures and components, in addition to composition and diversity of the chironomid assemblage, were used to trace a comprehensive picture of past changes. Radiometric dating was conducted to assess the temporal context of the sedimentary series. The results reveal that Ellasjøen is a climatically sensitive lake and preserves a history of substantial changes. A general pattern is detected where Medieval Warm Period features very modest warmth, followed by warming summer temperatures until 1600 AD, when the temperature trend starts to decrease towards culmination of the Little Ice Age at 1740 AD. A warming trend ever since is persistent but does not exceed past warmth. Results suggest higher seasonality during Little Ice Age and seek to explain causes for modest recent warmth. Reconstructed climate development is in good agreement with recent results from surrounding areas and a complex set of ice-ocean-atmosphere interactions is proposed as driving factors. The findings of this study highlight the importance of regionally solved high-resolution climate records and tracing of seasonal climate components to fully understand the variation and interrelationship of driving factors affecting the Arctic climate dynamics in the eastern North Atlantic sector.
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(2018)Lake sediments from Valkea–Kotinen, a small lake in the Evo area of southern Finland, were analysed to provide a high–resolution reconstruction of the fire episode and vegetation structure histories of the past ca. 1700 years at the site. Mixing of sediment was a problem in approximately the top half of the core, affecting the accuracy of the chronology and the correct interpretation of pollen and charcoal accumulation. Six local fire episodes were identified using the CharAnalysis program with a mean fire return interval of 312 years. None these episodes could be attributed to human activities with the exception of the episode at ca. 15 cal yr BP which may have been due to the controlled burning of forest for regeneration elsewhere in Evo. The vegetation structure was typical for southern Finland with Picea, Pinus, Alnus, and Betula dominating the site. Signals of human activity such as an increase in Cerealia pollen alongside an increase in microcharcoal from ca. 1000 cal yr BP indicate regional slash and burn activity. An episodic Alnus decline is evident from ca. 1400 cal yr BP with a subsequent recovery at around 1000 cal yr BP. The results show that the local fire regime at Valkea–Kotinen is likely natural and the vegetation structure has been consistent with little anthropogenic influence over the last ca. 1700 years.
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(2013)Kalliojärvi, Ania and Erkkilä gold deposits are located in the Pirkanmaa migmatite belt in southern Finland. Nearest city is Tampere, approximately 15 km northeast of the deposits. The native gold occurs with sulphide dissemination in quartz veins and shear zones in hydrothermally altered mica schist, gneiss and granite-pegmatite intrusions and black schist. Black schist is common in Erkkilä deposit. Tourmaline pegmatite is common in Ania deposit. Gold grades are in the range of 0,1-26,7 g/t. The peak of metamorphism has reached upper amphibolite fasies in Erkkilä deposit (K-feldspar + sillimanite isograd). In Kalliojärvi the metamorphic index mineral is staurolite, which indicates middle amphibolite facies conditions. In Ania the metamorphism has progressed to the lower amphibolite facies stability field of garnet. These metamorphic associations indicate pressure of 8 kb to 6 kb and temperature of 790 to 525 °C. The hydrothermal alteration is strong in the mineralized zones, demonstrated by silicification and potassium metasomatism, which altered feldspars to sericite and biotite to chlorite. Plagioclase has also altered to albite and potassium feldspar, epidote and calcite and ilmenite has altered to rutile. In the mineralisation process fluids have enriched in the same ore forming elements in all three deposits. These elements include Fe, Cu, Ni, Co, Au, Ag, Hg, Pb, Bi, Sb, Te, S, Se, As. The major ore minerals are arsenopyrite, löllingite, pyrrhotite, pyrite and chalcopyrite. Other ore minerals are native bismuth, gold, bismuth tellurides, maldonite and oxide minerals. The major ore forming process has been open space filling. The ore minerals have crystallized as disseminations in intergranular spaces between silicates and carbonates, in quartz- and epidote-clinozoisite veins and walls of the fluid channels. The arsenopyrite geothermometry shows crystallization temperature from 438 to 609 °C with pyrrhotite and löllingite. The sulfur activity (logS2) has been from -3,70 to -8,30. Fluids transported gold predominantly as a reduced sulphur complex and a thioarsenide complex. The first generation native gold is intergrown and as inclusions in arsenopyrite and in grain borders of composite löllingite and arsenopyrite grains. The second generation native gold occurs as open space fillings in the gangue fractures, intergranular spaces between silicates and as inclusion in potassium feldspar and sulphides, Bi-, Sb- Te-minerals and metallic bismuth. The main crystallization of native gold and tellurides took place in the epizonal temperature range from 150 to 300 °C. According to the mineral liberation analyses in Ania the grain size of gold, 86,10 wt. %, is from 32 to 106 µm, in Erkkilä 98,22 wt. % is from 32 to 355 µm and in Kalliojärvi 76,02 wt. % is from 32 to 106 µm. In heavy mineral concentrates gold occurs as free grains and also intergrown with arsenopyrite and bismuth. A small portion of gold is as inclusions in other minerals in arsenopyrite and silicates. The mineralisation and crystallization of the ore minerals is epigenetic i.e. it was active after the last metamorphic event in shear zones of the host rock. All three gold deposits have crystallized after a complex, accretionary to collisional orogenic evolution of Svekofennian. The ore mineral crystallization occured in the hypozonal-epizonal temperature range from 600 to 150 °C.
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(2013)The Litorina Sea is the latest Baltic Sea stage, which has dated to begin about 9000−7500 years ago. The sea phase developed after the Ancylus Lake when the straits of Denmark opened, and it is a distinctive phase within the Baltic Sea history. This MSc thesis aims to create a GIS based database about the highest stand of the Litorina Sea in Finland and to reconstruct its extent by interpolating it's shorelines with the resolutions of 10 and 25 meters. The purpose was also to make an updated version of the highest Litorina Sea shoreline map by Eronen and Haila 1992. The highest shoreline of the Litorina Sea can be observed in ancient shoreline relicts such as stone belts, beach ridges, cliffs and terraces. The widest extent of the Litorina Sea's brackish water can be detected from isolation horizons within mire and lake sediments. It can be distinguished as Clypeus limit or physically as a chance where the clays of the Ancylus Lake turn into clays of the Litorina Sea. The highest shoreline of the Litorina Sea is diachronous and its level in different regions of Finland varies due to the uneven uplift and inclining of the shorelines. It is important to note that the highest shoreline of the Litorina Sea has occurred in some regions at the beginning of the Litorina Sea stage like in Ostrobothnia or later by the time of the Litorina transgression in other places like in southern Finland. Depending on the location, the highest shoreline of the Litorina Sea occurred about 8000−6500 year ago due to its diachronity and the impact of transgression. All known shoreline and isolation observations were collected from the literature in the database with the help of LiDAR DEM with a resolution of two meters, and DEM 25. Observations were used to create a database with the information of coordinates and observed altitude. The aim was also to find new shoreline sites. Altogether 564 shoreline observations and 102 isolation observations were collected in the database and they were classified to five classes according to their reliability. The highest shoreline of the Litorina Sea (LI) was reconstructed with the help of the best observation points by using vector based TIN interpolation. Two different resolution LI representing rasters were created by subtracting the formed TIN model from two separate DEM models: DEM 10 and DEM 25. Calculated raster grids represent the relative altitude and the depth of the Litorina Sea at its highest stage in different areas. These rasters were classified into two classes, which other class represents area covered with water and other represents land area, and they were converted into polygons. Modeling was challenging because observations were not evenly distributed among the sphere of influence of the Litorina Sea. The altitude of LI increases in north-west direction from about 21 m in Virolahti area to about 32 m in Helsinki area, 45-52 m in Turku and Pori and to 100 m in Ostrobothnia area. Highest observation altitude of the Litorina Sea is in Ylitornio in the slopes of the Huitaperi at the level of 108.4 m. The results of the modeling resemble earlier maps of the highest shoreline of the Litorina Sea but they are more detailed. On the other hand the 25 m resolution map is still very coarse reflecting the errors of DEM 25 model. However, the 10 m resolution map is rather detailed, but it still needs some enhancement. Ancient Shoreline Database and associated fine-resolution maps are published to facilitate and promote the research related to the highest stage of the Litorina Sea.
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(2017)Earlier field work in the 1.64 Ga Ahvenisto AMCG (anorthosite-mangerite-charnokite-granite) complex has revealed mafic and felsic magma interaction between hornblende granite and monzodioritic rocks, but a detailed description of this interaction has not previously been presented. In this study field observations, detailed mapping, petrography, geochemistry, and melt viscosity modeling are utilized to provide a comprehensive description of magma interaction processes and the related rock types. Two major mafic and felsic interaction processes, both also observed in the Ahvenisto complex, are mingling and mixing. Mingling is observed in the form of monzodioritic pillows with finger-like granitic veins protruding in them. Mixing is observed as a hybrid rock with monzodioritic groundmass and K-feldspar phenocrysts. The monzodioritic rocks are presumed to represent the last liquids of the mafic magmas of the complex, and the hornblende granite and the granitic veins are presumed to represent the first felsic melts of the granitic intrusion stage. Observed mixing and mingling indicates that these two magmas were, at least partly, liquids simultaneously at the time of intrusion. Petrography and geochemistry reveals at least three different monzodioritic rock types: olivine monzodiorite, ferrodiorite, and monzodiorite. These types represent partial melts of the monzodioritic magma, olivine monzodiorite being the least evolved and monzodiorite the most evolved. The vein granites originate from a more evolved partial melt of the hornblende granite superheated by the coeval mafic magma. Calculated mixing trends and melt viscosities with liquidus temperatures were used to evaluate the magma interaction styles between different rock types. Volatile contents of the two magmas played an important role: the felsic melts most likely contained higher amount of volatiles whereas the mafic melts were relatively dry. Mixing calculations reveal that the hybrid rock was produced by mixing of monzodioritic and hornblende granitic magmas. Mingling occur between ferrodiorite and the vein granites. The least evolved monzodioritic rock, olivine monzodiorite, shows minor interaction only and is probably a close representative of the 'primary' monzodiorite magma of the Ahvenisto complex.
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