The age of mid-proterozoic phosphatic metasediments in Finland as indicated by radiometric UPb dates     

Matti Vaasjoki  Olli Äikäs  Pentti Rehtijärvi 《Lithos》1980,13(3):257-262

Two uranium-bearing phosphatic metasedimentary occurrences at Lampinsaari, Vihanti and Temo, Nilsiä, in Finland have been dated by isotopic UPb analyses of whole rock samples to be 1876±2 Ma old. The dates reflect the time of the Svecokarelian regional metamorphism in high amphibolite facies. An analysis of a uranium thucolite from the deposit at Nuottijärvi, Paltamo, that was metamorphosed in intermediate greenschist facies gives a date of 1897±7 Ma, suggesting that the phosphatic sedimentation had occurred before that time. An upper time limit for the sedimentation is set by a previous date of 2080±45 Ma, which was obtained from a banded iron one formation. The absence of thorium in the deposits suggests a marine environment of deposition.  相似文献   

Book reviews     

W. M. Adams  R. Meissner  U. Vetter  G. Kunkel  W. Ritchie  E. Seibold  John E. Bardach  M. J. Orren  M. K. Seguin  G. Müller  Matti Karras 《GeoJournal》1979,3(3):321-328

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Sediment-related impacts due to upstream reservoir trapping, the Lower Mekong River   总被引：8，自引：0，他引：8  

Matti Kummu  Olli Varis 《Geomorphology》2007,85(3-4):275

A sharp decrease in total suspended solids (TSS) concentration has occurred in the Mekong River after the closure of the Manwan Dam in China in 1993, the first of a planned cascade of eight dams. This paper describes the upstream developments on the Mekong River, concentrating on the effects of hydropower dams and reservoirs. The reservoir-related changes in total suspended solids, suspended sediment concentration (SSC), and hydrology have been analyzed, and the impacts of such possible changes on the Lower Mekong Basin discussed. The theoretical trapping efficiency of the proposed dams has been computed and the amount of sediment to be trapped in the reservoirs estimated. The reservoir trapping of sediments and the changing of natural flow patterns will impact the countries downstream in this international river basin. Both positive and negative possible effects of such impacts have been reviewed, based on the available data from the Mekong and studies on other basins.  相似文献   

Eemian crustal deformation in the eastern Baltic area in the light of the new sites at Peski, Russia and Põhja-Uhtju, Estonia     

Arto Miettinen  Heikki Haila  Hannu Hyvrinen  Katja Rinne  Matti Eronen 《Quaternary International》2005,130(1):31

Several Eemian (Mikulino) marine deposits are known from the northwestern part of Russia and from Estonia. The best-known deposits are situated at Mga, Russia and at Prangli, Estonia. Two new sites with clayey and silty deposits covered by till were studied for pollen and diatoms at Peski, Russia and Põhja-Uhtju, Estonia. At Peski, the deposit representing the Eemian Interglacial is 3.8 m thick at the depth of 13.4–9.6 m above present sea-level. At Põhja-Uhtju, the deposit representing the Eemian is 3.5 m thick at the depth of 47.9–51.4 m below present sea-level. Although Peski is situated at a higher altitude than Põhja-Uhtju at present, the diatom stratigraphy at these sites indicates deeper and more saline conditions in the Peski area than at Põhja-Uhtju during the Eemian. This result is similar to some previous studies, which indicate, that although the Russian deposits (e.g. Peski, Mga) are now at a higher altitude than those in Estonia (Põhja-Uhtju and Prangli), the diatoms in the Russian deposits are indicative of a considerable depth of water during the time of deposition. These deposits suggest that the Eemian shore levels ascend from Estonia eastwards, while the Late Weichselian and Holocene shorelines tilt downwards in the same general direction. The present material from Estonia and northwestern part of Russia shows marked differences between the Eemian and Late Weichselian/Holocene crustal deformations, which probably resulted from different ice loads during the final glaciation phases and probably also from different deglaciation patterns during the Saalian and Late Weichselian.  相似文献   

Stream water geochemistry from selected catchments on the Kola Peninsula (NW Russia)and in neighbouring areas of Finland and Norway: 1. Elements levels and sources     

Patrice de Caritat  Clemens Reimann  Matti Äyräs  Heikki Niskavaara  Viktor A. Chekushin  Vladimir A. Pavlov 《Aquatic Geochemistry》1996,2(2):149-168

The pH, electrical conductance and concentration of six anions and 33 cations were determined in stream waters sampled in 1994 from eight arctic catchments on and adjacent to the Kola Peninsula (Russia, Finland and Norway). The catchments are located at various distances (5–300 km) from the major industrial emissions centres of Monchegorsk, Nikel and Zapoljarniy in Russia. The source of the elements can be (1) natural, marine (sea spray), (2) natural, geogenic (blowing soil/dust, till, bedrock), and/or (3) anthropogenic, industrial (emissions from smelters, dust from mining, etc.), each source showing a distinct signature. The median concentration of many contaminants can vary by up to three orders of magnitude from polluted to remote locations, and the concentration ranges observed in different catchments often do not overlap. This implies that contamination falls sharply with distance from source, but is quite profound and lasting close to the emission centres. Elevated trace metal contents in the most polluted streams indicates that deposited contaminants are transferred to the aquatic ecosystem, and eventually can reach the ocean.  相似文献   

Stream water geochemistry from selected catchments on the Kola Peninsula (NW Russia) and in neighbouring areas of Finland and Norway: 2. Time-series     

Patrice de Caritat  Clemens Reimann  Matti Äyräs  Heikki Niskavaara  Viktor A. Chekushin  Vladimir A. Pavlov 《Aquatic Geochemistry》1996,2(2):169-184

Stream water composition, measured weekly for 8–9 months in 1994 in three arctic catchments on and around the Kola Peninsula (Russia, Finland and Norway), is presented in the form of time-series. In all three catchments, snowmelt causes a major dilution of the stream water, as reflected by marked dips in electrical conductance. In the most polluted catchment (C2), the snowmelt flood (the major hydrological event at these latitudes) is reflected in the stream water by a pH dip and a pulse in technogenic heavy metals (Cu, Ni, etc.), Al and S. This results from melting of the snow laden with heavy metals and sulphate, and from leaching of the topsoil layer. In the most pristine catchment (C8), snowmelt causes no heavy metal pulse (remote location) but yields an increase in stream water Al (acidic lithology/overburden). In the intermediate catchment (C5), very subdued heavy metal and S increases are noticeable in the stream water, whilst its pH increases steadily until summer (basic lithology). Some elements (Cl, S) may be mobilised out of the snowpack before its complete thawing and reach the stream 1–2 weeks ahead of the heavy metals. The substrate (soil, overburden and bedrock) of a catchment controls to a large extent its ability to buffer acid inputs.  相似文献   

Multipurpose geochemical maps produced by integration of geochemical exploration data sets in The Paraná Shield, Brazil     

Otavio Augusto Boni Licht  Timo Tarvainen 《Journal of Geochemical Exploration》1996,56(3):167-182

Old geochemical datasets from the Paraná Shield of southern Brazil have been integrated into a new geochemical database and the results are presented as a series of multipurpose geochemical maps. Although the 24 datasets retrieved were analysed by three different laboratories, the maps produced correlate surprisingly well with bedrock geological features.The retrieval of old geochemical exploration data sets for the purpose of generating maps showing element depletions and enrichments is a powerful tool with a wide range of applications: trace elements such as Zn, Cu and Mo can significantly affect crop productivity; areas with high abundances of harmful elements such as As and F can be delineated in order to identify public health hazards; heavy metals such as Cd, Pb and Hg can be measured in order to better constrain knowledge of chemical background levels for environmental monitoring. The integration and manipulation of different data sets can however be complicated by the heterogeneity in sampling and analytical procedures.  相似文献   

The normative mineralogy of 10 soil profiles in Fennoscandia and north-western Russia     

R. Salminen  V. Gregorauskiene  T. Tarvainen 《Applied Geochemistry》2008,23(12):3651-3665

The mineralogical composition of soil horizons in different soil types of different ages was estimated by applying the NORMA software, which was developed originally for calculating the normative mineralogical composition of young podsols. Ten soil profiles from six sites in NW Russia, two in Finland, and one in NE Norway were sampled in 1999 as a part of the pilot phase of a large geochemical mapping project. Total element concentrations were determined from the <2 mm fraction by XRF from powdered pellets for Al, Ca, Cr, Fe, K, Mg, Mn, Na, P, S, Si, Ti, and Zr, and for Ba by ICP-AES after HF+HClO₄ extraction. Extractable concentrations for Al, Ca, Cr, Fe, K, Mn, Mg, Na, P, S, Ti, Zr, and Ba were determined by ICP-MS or ICP-AES after aqua regia (a 1:3 mixture of strong HCl and HNO₃) extraction. Total C was determined using a thermal conductivity detector from a sample burned in an O₂ stream. The NORMA software was used to calculate the percentage of normative soluble minerals pyrite, apatite, titanite, calcite, biotite, chlorite, weathered albite, hydrous Al-silicate, goethite and soluble residue. The percentages of non-soluble normative minerals rutile, hornblende, K-feldspar, albite, anorthite, tremolite, wollastonite, kaolinite, magnetite, zircon, quartz, carbon (graphite), and non-soluble residue were calculated after soluble minerals.The calculated mineralogical composition of C-horizon samples in each profile reflected the known geological composition of the bedrock from which the soil parent material was derived during geological processes. Secondary minerals including goethite and hydrous Al-silicates, were detected in upper soil horizons reflecting the development of soils. Rather than age, the local bedrock geology together with the mineralogical composition and chemical properties of the parent material proved to be the controlling factor in the formation of secondary minerals. The results showed that the NORMA method can be used in defining the mineralogy of soil horizons in a large variety of soil types.  相似文献   

Reply to Janna Turkia's comment of Virkanen et al. (1997)     

Juhani Virkanen  Atte Korhola  Matti Tikkanen  Tom Blom 《Journal of Paleolimnology》1998,20(1):104-104

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The isolation of Kruunuvuorenlampi, southern Finland, and implications for Holocene shore displacement models of the Finnish south coast     

Heikki Seppä  Matti Tikkanen 《Journal of Paleolimnology》1998,19(4):385-398

In the southern coastal area of Finland, many studies exist on shore displacements related to the higher Ancylus Lake and Litorina Sea altitudes. However, the late- Holocene shore displacement history is much less known and the shore displacement models are based on interpolations. Kruunuvuorenlampi, a small lake located at an altitude of 8.6 m a.s.l., was studied to test the reliability of the interpolated models. The cores revealed an unusual bottom lithostratigraphy, with a coarse gravel and sand layer sandwiched between the lower marine clays and upper shallow-water clay-gyttja. Analysis of diatoms, pollen and loss-on-ignition, together with radiocarbon datings, were carried out to determine and date the isolation event of the lake. The results show that the lake was isolated ca. 2400 ¹⁴C years BP and that the coarse grained layer was deposited prior to the isolation. The reconstruction of the emergence of the lake basin area suggests that the coarse grained layer originated from strong wave erosion of the shores before the isolation. This interpretation is supported by the presence of a wave-washed boulder belt on the NE slope of the basin. The isolation of Kruunuvuorenlampi lies exactly on the interpolated shore displacement model of the 30 m Litorina isobase. This placement suggests that no significant transgressions took place between the Litorina transgression and the isolation of Kruunuvuorenlampi.  相似文献