Mid‐Weichselian interstadial in Kolari,western Finnish Lapland

Finnish Lapland is known as an area where numerous sites with sediments from Pleistocene glacial and interglacial periods occur. Recent sedimentological observations and dating call for reinterpretation of the record, which shows a complicated Mid‐Weichselian ice‐sheet evolution within the ice‐divide zone. Here, a large, previously unstudied section from a former Hannukainen iron mine was investigated sedimentologically and dated with optically stimulated luminescence (OSL). Ten sedimentary units were identified displaying a variety of depositional environments (glacial, glaciolacustrine, fluvial and aeolian). They are all – except for the lowermost, deeply weathered till – interpreted to be of Mid‐ or Late Weichselian/Holocene age. Five OSL samples from fluvial sediments give ages ranging from 55 to 35 ka, indicating two MIS 3 ice‐free intervals of unknown duration. The Mid‐Weichselian interstadial was interrupted by a re‐advance event, which occurred later than 35 ka and caused glaciotectonic deformation, folding and stacking of older sediments. This new evidence emphasizes the importance of the Kolari area when unravelling the complex Late Pleistocene glacial history of northern Finland and adjacent regions.     

A closed-loop EKF and multi-failure diagnosis approach for cooperative GNSS positioning

Current cooperative positioning with global navigation satellite system (GNSS) for connected vehicle application mainly uses pseudorange measurements. However, the positioning accuracy offered cannot meet the requirements for lane-level positioning, collision avoidance and future automatic driving, which needs real-time positioning accuracy of better than 0.5 m. Furthermore, there is an apparent lack of research into the integrity issue for these new applications under emerging driverless vehicle applications. In order to overcome those problems, a new extended Kalman filter (EKF) and a multi-failure diagnosis algorithm are developed to process both GNSS pseudorange and carrier phase measurements. We first introduce a new closed-loop EKF with partial ambiguity resolution as feedback to address the low accuracy issue. Then a multi-failure diagnosis algorithm is proposed to improve integrity and reliability. The core of this new algorithm includes using Carrier phase-based Receiver Autonomous Integrity Monitoring method for failure detection, and the double extended w test detectors to identify failure. A cooperative positioning experiment was carried out to validate the proposed method. The results show that the proposed closed-loop EKF can provide highly accurate positioning, and the multi-failure diagnosis method is effective in detecting and identifying failures for both code and carrier phase measurements.     

Crushed aggregate—bentonite mixtures as backfill material for repositories of low- and intermediate level radioactive wastes

The candidate backfill materials for the repositories of low- and intermediate-level radioactive wastes consist of three components: crushed rock aggregate, finely ground rock aggregate and bentonite. The hydraulic conductivity of mixtures with 15% of sodium bentonite is approximately 5 · 10^-9m/s based on the laboratory tests. The sweling potential for the same material varies between 20 and 60 kPa depending mainly on the salinity of the groundwater.     

Lithogeochemistry in exploration for Proterozoic porphyry-type molybdenum and copper deposits, southern Finland

Over 450 samples were collected around four Proterozoic porphyry-type occurrences and analyzed for 30 elements. Relatively broad primary halos are associated with all four occurrences in spite of their moderate size and grade. The halos are characteristic of each particular occurrence depending on the geological and geochemical conditions. Copper forms extensive and highly contrasted anomalies, whereas Mo anomalies are of limited size. Gold, Zn, Pb, As, and Sb seem to be useful pathfinders for slightly eroded or blind occurrences. Pyritization and wall-rock alteration are weaker than in Phanerozoic porphyry deposits, consequently, S halos are small and often erratic. K₂O, Rb, and SiO₂ produce weak anomalies near the core of the occurrences. A density of a few tens of samples per km² is required for detailed follow-up exploration.The host granitoids have normal chemical compositions outside the mineralized areas with low and constant background contents of ore elements and are thus very suitable for lithogeochemical exploration. On a regional scale a density of one to five samples per km² is sufficient to identify mineralized intrusive phases and areas, because the porphyrytype occurrences were formed by extensive hydrothermal processes, which produced scattered anomalies over large areas.     

Mode of occurrence of Cu and Zn in till over three mineralized areas in Finland

The variation of Cu and Zn contents with grain size was studied in the size fractions: 2000-500 μm, 500-64 μm, 64-2 μm and minus 2 μm. The fixation to different minerals was investigated in the 500-64 μm and minus 64 μm fractions with microscope, microprobe, electron microscope and X-ray diffraction after heavy-liquid separation.The distribution of Cu and Zn between the four size fractions is very similar in all target areas. The contents tend to be highest in the minus 2 μm fraction, and to decrease with increasing grain size except for an increase in the coarsest material. This feature is typical in mineralized areas with till having anomalously high Cu and Zn contents.The anomalous Cu and Zn in the till of Talvivaara are mainly fixed to chalcopyrite and sphalerite, respectively, which indicates that the main part of the material originates from fresh bedrock and that postglacial alterations are slight. In the till of Outokumpu and Maaselkä sulphides are rare. We assume that in Outokumpu the reason for this is the postglacial weathering of sulphides and that in Maaselkä a great deal of till derives from highly weathered, sulphide-poor, preglacial regolith. In both target areas Cu in till seems to fix to limonite and also to clay minerals, particularly in Maaselkä. Zinc seems mainly to be hosted by limonite in Outokumpu.     

Consequences of transducer inductance for seismograph calibration

Summary The magnification achieved with the standard sine-wave method using seismometers with the calibration and signal coils tightly wound on the same coil former can be erroneous at high frequencies due to the mutual inductance between both coils. An attempt was made to eliminate this influence from the calibration data. The application of theoretical equations was tested with a short-period digital seismograph.

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Autoradiography and scanning electron microscopy combined with energy-dispersive spectrometry (SEM-EDS) in the service of geochemical exploration

The importance of the identification of the mineral phases in the heavy fractions of geochemical samples is emphasized. A knowledge of the chemical composition with information about the anomalous contents of the economically interesting metals in the samples is not sufficient, it is also essential to know the mineralogical source of the metals especially when the exploitation possibilities of the searched-for deposits are being estimated. A version of autoradiography suitable for the location and quantitative determination of radioactive minerals in the heavy fractions of geochemical samples is described. Furthermore, the use of a scanning electron microscope (SEM) equipped with an energy-dispersive spectrometer (EDS) in the identification of the heavy minerals is also described. An example of the use of SEM-EDS identification of radioactive minerals, located by the autoradiography, is described.     

Fishermen responses on marine protected areas in the Baltic cod fishery

Much of the research that concerns the impacts of management measures in the eastern Baltic cod fishery has focused on fish stock rather than understanding fishermen's attitudes towards regulations. Hence, there is little information available on fishermen's responses although they are the ones whom the regulations affect most profoundly. This study analyses the views of fishermen towards management measures with an emphasis on fishing closures (marine protected areas, MPAs). Swedish log-book data from 1996 to 2005 were used to describe MPA induced fishing effort displacements. Fishermen argued that MPAs have been inefficient in conservation of cod stock. The enlargement of Bornholm MPA in 2005 caused substantial effort displacement towards areas dominated by smaller sized fish. This contributed to the increased discarding of juvenile cod. Enlarged MPAs also intensified competition between different fleet segments and reallocated fishing areas. To reduce fishing mortality, fishermen suggested days-at-sea (effort) regulation and an effective landings control system for all fleets that exploit cod stocks in the Baltic Sea Main Basin. These measures would better motivate fishermen for mutual rule compliance, which is a prerequisite for a sustainable cod fishery.