Agency: GTR | Branch: NERC | Program: | Phase: Research Grant | Award Amount: 401.39K | Year: 2011
Future climate change is one of the most challenging issues facing humankind and an enormous research effort is directed at attempting to construct realistic projections of 21st century climate based on underlying assumptions about greenhouse gas emissions. Climate models now include many of the components of the earth system that influence climate over a range of timescales. Understanding and quantifying earth system processes is vital to projections of future climate change because many processes provide feedbacks to climate change, either reinforcing upward trends in greenhouse gas concentrations and temperature (positive feedbacks) or sometimes damping them (negative feedbacks). One key feedback loop is formed by the global carbon cycle, part of which is the terrestrial carbon cycle. As carbon dioxide concentrations and temperatures rise, carbon sequestration by plants increases but at the same time, increasing temperatures lead to increased decay of dead plant material in soils. Carbon cycle models suggest that the balance between these two effects will lead to a strong positive feedback, but there is a very large uncertainty associated with this finding and this process represents one of the biggest unknowns in future climate change projections. In order to reduce these uncertainties, models need to be validated against data such as records for the past millennium. Furthermore, it is extremely important to make sure that the models are providing a realistic representation of the global carbon cycle and include all its major component parts. Current models exclude any consideration of the reaction of peatlands to climate change, even though these ecosystems contain almost as much carbon as the global atmosphere and are potentially sensitive to climate variability. On the one hand, increased warmth may increase respiration and decay of peat and on the other hand, even quite small increases in productivity may compensate for this or even exceed it in high latitude peatlands. A further complication is that peatlands emit quite large quantities of methane, another powerful greenhouse gas. Our proposed project aims to assess the contribution of peatlands to the global carbon cycle over the past 1000 years by linking together climate data and climate model output with models that simulate the distribution and growth of peatlands on a global scale. The models will also estimate changes in methane emissions from peatlands. In particular, we will test the hypotheses that warmth leads to lower rates of carbon accumulation and that this means that globally, peatlands will sequester less carbon in future than they do now. We will also test whether future climate changes lead to a positive or negative feedback from peatland methane emissions. To determine how well our models can simulate the peatland-climate links, we will test the model output for the last millennium against fossil data of peat growth rates and hydrological changes (related to methane emissions). To do this, we will assemble a large database of published information but also new data acquired in collaboration with partners from other research organisations around the world who are involved in collecting information and samples that we can make use of once we undertake some additional dating and analyses. Once the model has been evaluated against the last millennium data, we will make projections of the future changes in the global carbon cycle that may occur as a result of future climate change. This will provide a strong basis for making a decision on the need to incorporate peatland dynamics into the next generation of climate models. Ultimately we expect this to reduce uncertainty in future climate change predictions.
Mattila J.,Geological Survey of Finland |
Geology | Year: 2012
The relationship between present-day stress state and fluid flow within fractures in crystalline bedrock is investigated in the light of a comprehensive fracture database consisting of 38,703 fracture observations made during investigations at the site of a planned high-level nuclear waste repository in Finland. By combining fracture orientation data with detailed stress and fluid flow measurements, we observe that the orientations of conductive fractures display characteristic patterns attributed to the effect of the present-day triaxial stress state and that the highest transmissivities are associated with fractures having the lowest normal tractions. Our findings indicate that contemporary stress data combined with slip and dilation tendency analysis can be used in predicting the orientations and relative transmissivity values of conductive fractures. © 2012 Geological Society of America.
Ruotoistenmaki T.,Geological Survey of Finland
Journal of African Earth Sciences | Year: 2014
During the years 2008-2012, the geology of most of Uganda was studied within the framework of the Sustainable Management of Mineral Resources Project (SMMRP). During the project, comprehensive airborne magnetic and radiometric surveys were flown over the entire country and geological, petrophysical, geochemical sampling, geological field studies and detailed geophysical field profiles were undertaken in selected sub-areas. This report concentrates on the geophysical properties of three major geophysical structures in the area considered during the project: the Pan-African (0.6-0.7. Ga) Aswa shear zone and Nagasongola discontinuity (suture), and the 1.36. Ga Uganda-Tanzania semi-circular 'ring dyke' complex.The geophysical profiles across the Aswa shear indicate that the fault zone dips steeply, at about 60° to NE. The structure represents a magnetic, gravimetric (density), radiometric and topographic discontinuity, all diminishing from SW to NE across the zone. The zone is also characterized by complex radiometric anomalies. A schematic reconstruction of the evolution of the Aswa shear zone on the magnetic map suggests a nearly 60. km sinistral horizontal component of displacement along the zone. The Nakasongola zone is another distinct magnetic, gravimetric and radiometric discontinuity, interpreted to represent a collision (suture) zone, where the northern, low-magnetic block has been thrust over the southern, denser and more magnetic block. Modeling of gravity and magnetic data are consistent with a geometry in which the southern, magnetic and high-density block dips gently to great depth beneath the northern block. Bedrock exposures in both the Aswa shear zone and Nagasongola zone areas indicate a very protracted and complex history of tectonic processes commencing in the Archaean-Paleoproterozoic era and culminating in Pan-African orogenies. Both, the Aswa shear zone and Nagasongola discontinuity are cut by continuous younger dykes that show no signs of disruption, indicating that these deformation zones are presently relatively inactive. Thus, the dating of these dykes can constrain estimates of minimum activation ages of the structures that they transect.The semicircular ring dyke complex in SW Uganda, which continues southwards across Lake Victoria to NW Tanzania, is most clearly visible in magnetic anomaly maps as curved anomalies with a diameter of about 450-650. km. Magnetic profile interpretations across the dykes in Tanzania and Uganda indicate that the dykes dip at about 30-40° towards the geometric center of the concentric rings, implying a cone shaped geometry for the dykes in three dimensions. Minimal offsets in anomalies cut by dykes indicate that the dykes were not intruded within fault zones associated with major dislocations, rather that they were emplaced within extensional fractures due to uplift above a mantle plume below the conical dyke complex.The present study, based on the results of the SMMRP, gives valuable, but still preliminary new information concerning large scale tectonic processes operating in the bedrock of Uganda. The structures described here can all be potentially related to hydrothermal events and enrichment of elements of economic interest. © 2014 Elsevier Ltd.
Vallius H.,Geological Survey of Finland
Marine Pollution Bulletin | Year: 2015
The Gulf of Finland is a shallow sea where a multitude of activities compete of space. Many of the activities include reworking of the sea floor. The gulf is known to have been rather largely contaminated by heavy metals during the last century, and although indications of recovery have been reported, it is crucial to know the levels of sea floor sediment contamination before any decisions of activities are taken by the authorities. In order to predict sediment toxicity the sediment concentrations acquired during a study from 2001 to 2004 are compared to Canadian sediment quality guidelines (SQG: s), which reveal that in the majority of the subsamples the metals and arsenic exceed the threshold levels of the used SQG: s, some exceed also the probable effect level. As, Cd, Hg, and especially Zn concentrations occur at unacceptably high levels in the coastal Gulf of Finland sediments. © 2015 Elsevier Ltd.
Kietavainen R.,Geological Survey of Finland |
Purkamo L.,VTT Technical Research Center of Finland
Frontiers in Microbiology | Year: 2015
The emerging interest in using stable bedrock formations for industrial purposes, e.g., nuclear waste disposal, has increased the need for understanding microbiological and geochemical processes in deep crystalline rock environments, including the carbon cycle. Considering the origin and evolution of life on Earth, these environments may also serve as windows to the past. Various geological, chemical, and biological processes can influence the deep carbon cycle. Conditions of CH4 formation, available substrates and time scales can be drastically different from surface environments. This paper reviews the origin, source, and cycling of methane in deep terrestrial crystalline bedrock with an emphasis on microbiology. In addition to potential formation pathways of CH4, microbial consumption of CH4 is also discussed. Recent studies on the origin of CH4 in continental bedrock environments have shown that the traditional separation of biotic and abiotic CH4 by the isotopic composition can be misleading in substrate-limited environments, such as the deep crystalline bedrock. Despite of similarities between Precambrian continental sites in Fennoscandia, South Africa and North America, where deep methane cycling has been studied, common physicochemical properties which could explain the variation in the amount of CH4 and presence or absence of CH4 cycling microbes were not found. However, based on their preferred carbon metabolism, methanogenic microbes appeared to have similar spatial distribution among the different sites. © 2015 Kietäväinen and Purkamo.
Vallius H.,Geological Survey of Finland
Marine Pollution Bulletin | Year: 2014
The Baltic Sea has received considerable loads of pollutants due to industrialization in Eastern Europe. Concern for the Baltic's ecological health eventually led to legislation and voluntary measures to limit pollution during the last decades of the 20th century. Heavy metal concentrations in open sea surface sediments reflected these steps to limit contaminant loads almost immediately, suggesting the possibility that the trend would continue in the ensuing years. Recent seafloor samples reveal that the declines have persisted over the past two decades. Currently, almost all heavy metal species have declined in surface sediments to levels approaching the safe limits for humans and the environment. Cadmium and mercury however remain at relatively high concentrations in many areas. Arsenic concentrations, which occur at safe levels within the Gulf of Finland persist at unacceptably high levels in surface sediments of the Bothnian Bay, and thus pose a potential threat to marine life in the area. © 2013 Elsevier Ltd.
Korpisalo A.,Geological Survey of Finland
Measurement: Journal of the International Measurement Confederation | Year: 2014
A new geophysical borehole prospecting method has been taken into use at the Geological Survey of Finland (GTK), known as the radiofrequency imaging method (RIM). RIM is a high-resolution technique and useful for second-stage explorations and ore body delineations, assisting, e.g. with strategic mine planning and large rock building projects to determine the structural integrity of the rock in the area of interest. It is a computerised tomography method that is based on the radiowave attenuation between the boreholes, making it possible to reconstruct the attenuation distribution of the borehole section (tomographic image). Under certain conditions it may also be possible to convert the high p-domain attenuation to the electric conductivity and use it to determine the relative permittivity in the low p-domain. The system consists of a continuous wave (CW) borehole transmitter and borehole receiver. The transmitter and receiver deploy insulated dipole antennas to radiate and receive electromagnetic energy. The borehole transmitter of the system is the core where the four measurements frequencies (312.5, 625, 1250 and 2500 kHz) and the vital references frequency (156.25 kHz) are generated. The reference has its importance in the proper detection of phase difference and amplitude. This paper presents the first experiences with the RIM device in Finland, dealing with the technical characteristics of the instrument and comparisons with results measured by other systems (resistivity logging and transient electromagnetic method). Presently, the device is the main part of the borehole system known as EMRE (ElectroMagnetic Radiofrequency Echoing).
Saarnisto M.,Geological Survey of Finland
Quaternary International | Year: 2012
The emergence of eight small lake basins from the Lake Ladoga basin waters in the Island of Valamo (Valaam), NW Russia was studied to work out the Late Holocene uplift history of the area. All eight small lake basins in the Island of Valamo (Valaam) emerged from Lake Ladoga when the water level fell 12 m in connection of the formation of River Neva, the current outlet of the lake. The consistent Valamo data is in harmony with the results from Kilpolansaari, north-western Lake Ladoga and show that River Neva originated 3100 14C BP, in corrected radiocarbon years at 3350 cal BP.Since the origin of River Neva, the island of Valamo has been uplifted 3-3.5 m more than the Neva threshold area at Porogi, as shown by the tilted transgression shoreline of Ladoga before the Neva was formed. One millimetre difference in annual uplift during the past 3000 years, which is the difference in the current uplift rate, explains this height difference, suggesting passive neotectonics in the area during the Late Holocene. This result conflicts with Russian geodetic measurements showing anomalously high uplift rates, up to 6.4 mm/y, in the north-east Ladoga area, where uplift values are 1-2 mm/y according to Fennoscandian isobase maps.The above land uplift anomaly within Precambrian shield terrain far from the uplift centre around the Gulf of Bothnia would be difficult to explain. The isobase maps of present-day Fennoscandian uplift indicate a highly regular dome-shaped uplift pattern with no anomalies at a regional scale. The suggested anomalous Holocene uplift discoveries in the Gulf of Finland and southern Gulf of Bothnia areas are challenged, whereas strong palaeoseismicity resulting from rapid land uplift, immediately following deglaciation of the Scandinavian Ice Sheet, resulted in earthquakes, bedrock dislocations and massive rock falls, e.g. in the northern Lake Onega area and Lapland. © 2011 .
Mertanen S.,Geological Survey of Finland |
Korhonen F.,Geological Survey of Finland
Precambrian Research | Year: 2011
Charno-enderbitic granitoids in the Karelia craton of the Fennoscandian shield have been studied paleomagnetically. The characteristic remanence component has a steep negative inclination and is interpreted to record magnetization at a maximum age of 2684 ± 2 Ma. Consistently stable results were obtained from 12 sites in the Koitere area, corresponding to regions with high positive magnetic anomalies and high remanence intensities. Petrographic studies, coupled with rock magnetic investigations, indicate that the remanence resides in fine SD/PSD magnetite grains formed during Neoarchean clinopyroxene alteration. Cross-cutting vertical/subvertical Paleoproterozoic dolerite dykes suggest that the Koitere granitoids are in their original orientations and were not affected by Svecofennian deformation at ca. 1.9-1.8. Ga. The Koitere granitoids have an opposite polarity compared to the steep positive inclination remanence direction of the previously studied ca. 2.63. Ga Varpaisjärvi enderbites and granulites. The data from Koitere and Varpaisjärvi imply that at ca. 2.7-2.6. Ga the Karelia craton was located at high latitudes of 80-60°, whereas previous paleomagnetic data from ca. 2.5. Ga formations in the Vodlozero terrane in NW Russia indicate a near-equatorial position. Comparison of paleomagnetic data from the Koitere and Varpaisjärvi granulite-grade rocks with rocks of similar age in the Superior craton shows that at ca. 2.7-2.6. Ga the Superior and Karelia cratons were located at high latitudes and in close proximity, although the present data cannot demonstrate that the cratons were amalgamated. However, during the Archean-Paleoproterozoic transition at ca. 2.50. Ga both cratons experienced significant rotation and drifting to near-equatorial paleolatitudes, suggesting that the Superior and Karelia cratons may have been attached at that time. © 2011 Elsevier B.V.
Loukola-Ruskeeniemi K.,Geological Survey of Finland |
Lahtinen H.,Talvivaara Exploration Ltd.
Ore Geology Reviews | Year: 2013
The Talvivaara deposit contains 1550Mt of ore averaging 0.22% Ni, 0.13% Cu, 0.49% Zn and 0.02% Co. The precursors of the host rocks were deposited 2.1-1.9Ga ago in a stratified marine basin. Fractured talc-carbonate rocks delineate the eastern border of the deposit and serpentinites and talc-carbonate rocks occur along the rift-related sequence to the north and south of Talvivaara. Characteristic features are high concentrations of organic carbon and sulphur with median values of 7.6% and 8.2%, respectively. Organic carbon is graphitic at present and a variety of sulphide textures occur, representing multiphase evolution during diagenesis, tectonic deformation and medium-grade regional metamorphism. The main sulphides of the Talvivaara ore are pyrrhotite, pyrite, sphalerite, chalcopyrite and pentlandite. Sulphides occur both as fine-grained disseminations and coarse grains or aggregates. Chalcopyrite mainly occurs in joint surfaces and quartz-sulphide veins and pentlandite occur as inclusions in pyrrhotite. Alabandite (MnS) occurs in black shales and black metacarbonate rocks. The early low-T sulphide minerals were overprinted by later stage processes. No framboidal pyrite is any longer present, but spheroidal pyrite with a grain size of <0.01mm and containing up to 0.7% Ni occurs. During the deposition of the organic-rich mud the anoxic/euxinic bottom waters were enriched in Ni+, Cu+ and Zn2+. Sulphur isotope δ34S values indicate mixing of sulphur derived from different processes or fractionation by sulphate reduction in a restricted basin. Both thermochemical and bacterial sulphate reductions were important for the generation of reduced sulphur. © 2012 Elsevier B.V..