Flandrian pollen deposition rates and tree-line history in northern Fennoscandia

Previous absolute polien diagrams from northern Fennoscandia yielded evidence for a retreat of the pine limit from an earlier extended position to a position near the modern one between about 5000 and 3000 B.P. New absolute pollen data from the sediment core of Domsvatnet, a small tundra lake near the eastern coast of Varanger Peninsula, are used to demonstrate a parallel retreat in the birch limit. Areas outside the modern birch limit were colonized by early Flandrian pioneer birch woods between 9500 and 9000 B.P. and remained as birch woodland through middle Flandrian times until a retreat started around 5000 B.P. leading to the present tundra situation.
The Domsvatnet core shows anomalous high pollen deposition rates combined with relatively rapid matrix sedimentation, suggesting that pollen from outside the basin has been washed in with allochthonous material and concentrated in the sediment.     

The Nordkalott Project: studies of Quaternary geology in northern Fennoscandia

The Quaternary geology of the Nordkalott area in northern Fennoscandia is depicted in five maps. The themes of the maps are: Quaternary deposits, glacial geomorphology and paleohydrography, ice-flow indicators, Quaternary stratigraphy and ice-flow directions. The maps are briefly presented and an outline of the glacial history of the Nordkalott area is given.     

Magnetic fabric and emplacement of the post-collisional Pomovaara Granite Complex in northern Fennoscandia

The Proterozoic Pomovaara Granite Complex in northern Finland comprises three separate highly magnetic granite stocks. They are discordant, apparently unfoliated and according to isotope data, a significant Archaean component characterizes the source of these granites. The three stocks are aligned in an array parallel to major trans-crustal faults as interpreted from both aeromagnetic and gravity data. Their younger age of 1.8 Ga, compared to the main tectonic events at 1.9 Ga in northern Fennoscandia, indicates their post-collisional nature with respect to these events. The anisotropy of magnetic susceptibility (AMS) was studied together with magnetic, gravity and geological data in order to assess the emplacement mechanisms of the Pomovaara Granite Complex, and the possible tectonic control of fault systems on the ascent and emplacement of granitic magma. The orientation of magnetic fabrics within the granite stocks indicates that the direction of the original magma upwelling was from the SW, parallel to the major fault zones that controlled, at the crustal scale, the ascent of granite magmas. The predominant NW–SE orientations of the minimum magnetic axes of the magnetic ellipsoid and the elongate shapes of the stocks indicate compression normal to the deep fault trend during the crystallization of the granite magma.     

Hydrogeochemistry of sulfur isotopes in the Kalix River catchment,northern Sweden

The³⁴S-to-³²S ratio in dissolved SO₄ has been studied in the Kalix River, Northern Sweden, and its catchment. Weekly sampling over 17 months revealed temporal variations from +5.3‰ up to +7.4‰ in the δ³⁴S values in the river. Snow and rain samples showed lower δ³⁴S values (average +5.6‰ and +5.0‰, respectively). The atmosphere is the major source for S in surface waters in the catchment, and the heavier δ³⁴S values in the river are a result of SO₄ reduction within the catchment.Most of the temporal variations in the δ³⁴S value in the river are caused by a mixing of water from the mountain areas (relatively light δ³⁴S) and the woodland. The δ³⁴S value is relatively heavy in the woodland tributaries because of bacterial SO₄ reduction in peatland areas influenced by groundwater.The highest δ³⁴S values were measured during the spring flood, in June and in November. These heavy δ³⁴S values are related to different types of water with diverse origins.The heavy δ³⁴S values coinciding with the early spring flood originate from peatland areas in the woodland. Relatively heavy δ³⁴S values (up to +14.4‰) were registered in mire water. Smaller variations of the δ³⁴S value during summer and early autumn most likely were caused by the input of ground-mire water during heavy rains. A correlation between increased TOC concentrations and increased δ³⁴S values was observed.The heavy δ³⁴S values in June and November probably originate from SO₄ reduction in bottom water and sediments in lakes within the catchment. Bottom water, enriched in³⁴SSO₄, was transported in the river during the spring and autumn overturn.     

外贝加尔大骨节病地区水文地球化学特征分析(英文)

本文通过对在外贝加尔大骨节病区水文地球化学研究结果表明,该地区天然水呈现出高浓度的磷(高达3.5mg/L),同时,锰、硅、铅等元素也呈现出高浓度的地球化学特征。分析水文地球化学数据,认为大骨节病可能与生物地球化学性质的多种因素有关系。进一步研究大骨节病的成因机制需要新的可靠的环境地球化学数据。     

Spring temperature variability in northern Fennoscandia AD 1693–2011

A reconstruction of spring (April–May) temperature for northern Fennoscandia developed from the Tornionjoki (Tornio river) long cryophenological record of ice break‐up dates, back to AD 1693, is presented. The record is strongly climatically sensitive and explains 67% of the variance in the instrumental data over the last 150 years. The record exhibits a stepped decrease in the duration of the river's ice cover by 14 days, equivalent to an increase in April–May mean temperature of approximately 2.5°C over the last three centuries. The relationship between the date of ice break‐up, and accumulated daily mean temperatures (>0°C) is investigated. Uncertainty in the observation of ice break‐up is also considered in addition to the potential of this time series for regional climate model validation. Copyright © 2011 John Wiley & Sons, Ltd.     

Common temperature signal in four well‐replicated tree growth series from northern Fennoscandia

Four Nordic temperature proxies based on tree growth at the northern timberline – ring‐width from Sweden and Finland, maximum latewood density from Sweden, and height increment from Finland – were compared. Three indexing methods were used to enhance the low (centennial and above), medium (decadal‐to‐multidecadal) and high (decadal‐to‐interannual) frequencies. The proxies are shown to have a strong temperature signal (common variance) at the interannual‐to‐multidecadal scale, while the multidecadal‐to‐centennial trends are less coherent, perhaps reflecting intra‐regional differences in growing conditions but more likely due to the more noisy regional curve standardization method used to retain the longest trends. Various methods of combining the four proxy series were explored and tested by comparison with four long temperature records from northern Fennoscandia. Only relatively high‐frequency, spline‐indexed series produced consistently positive verification statistics as a reconstruction model for summer temperature using all four proxies. Copyright © 2012 John Wiley & Sons, Ltd.     

Hydrogeochemistry of three watersheds (the Erlqis, Zhungarer and Yili) in northern Xinjiang, NW China

In the arid region of northern Xinjiang, one of the least-studied areas in China, three watersheds, namely those of the Yili, Zhungarer and Erlqis, have become the focus of attention due to rapidly increasing human population and water demands. The hydrogeochemistry of natural water from the three watersheds was investigated. The ionic chemistry of natural waters from these watersheds changes considerably on a regional scale. The waters are neutral to alkaline in nature and most of them are soft-fresh waters. The total dissolved solid (TDS) varies over two orders of magnitude with a mean value of 580 mg/L, about 1.2 times and 4.6 times those of the Huanghe (Yellow River) and the world spatial median, respectively, but only 40% and 0.8% of those of the Tarim and the western Alashan watersheds, respectively. Much of the solutes and physicochemical parameters in these waters are under the highest desirable limits of the World Health Organization (WHO) for drinking purpose and a plot of sodium adsorption ratio versus EC shows that most waters are of good water quality for irrigation. Water-rock interaction and saturation index (SI) for selected minerals are evaluated. The SI of these natural waters is out of equilibrium (undersaturated) with respect to major carbonates (calcite and dolomite) and evaporites (gypsum and halite). The high concentrations of alkali earth metals, alkalinity and the high (Ca + Mg)/(Na + K) and Na/Cl ratios indicate that the release of major solutes in these waters is controlled largely by dissolution processes of carbonate and partly by silicate weathering, while, cation exchange reactions, soil-salt leaching and evaporation processes also play an important role. The effects of local pollution are minimal in the montane and piedmont areas of these watersheds but are significant in the oases and central areas of the drainage basins.     

Changes of treelines and alpine vegetation in relation to post‐glacial climate dynamics in northern Fennoscandia based on pollen and chironomid records

Palaeoclimatic records derived from a variety of independent proxies provide evidence of post‐glacial changes of temperature and soil moisture in northern Fennoscandia. We use pollen percentage, pollen influx, stomatal and chironomid records from Toskaljavri, a high‐altitude lake in northern Finland, to assess how treelines and alpine vegetation there have responded to these climate changes. The evidence suggests that the cool, moist climate of the early Holocene supported birch forest in the area 9600 cal. yr BP onwards and that a rise of temperature triggered the immigration of pine at 8300 cal. yr BP. At 6100–4000 cal. yr BP altitudinal treeline in the area was formed by pine, in contrast to the modern situation where mountain birch reaches a higher elevation. Alpine vegetation also demonstrates clear changes. Plant communities typical of dry, oligotrophic heaths of northern Fennoscandia expanded during the dry climatic period at 7000–4000 cal. yr BP and decreased in response to cooler and moister conditions after 4000 cal. yr BP. Alpine plant communities favouring moist sites show an inverse pattern, expanding after a change towards moister climate after 4000 cal. yr BP. In a redundancy analysis (RDA), a statistically significant proportion of the variability in the total chironomid assemblages was captured by changes in the pollen types reflecting alpine vegetation typical of moist sites. Although chironomid community changes appeared to follow the major patterns in the alpine vegetation succession, the present study does not support a direct link between the changing treeline position and chironomid stratigraphy. Rather, the data indicate that the terrestrial and aquatic environments have each responded directly to the same ultimate cause, namely changing Holocene climate. Copyright © 2002 John Wiley & Sons, Ltd.     

Geochemical and metallogenic provinces: a discussion initiated by results from geochemical mapping across northern Fennoscandia

The concept of metallogenic province has won general acceptance in economic geology. It is agreed that metallogenic provinces offer good opportunities for exploration of new ore deposits. The concept of geochemical province is also established, but its exact meaning is disputable. In this paper, geochemical province is used as an abnormal spatial distribution of an element or element combination in a particular sample type as measured by a particular analytical technique. The practical consequences of this concept of geochemical provinces in mineral exploration seem not to have been fully utilized, although geochemical and metallogenic provinces could only be different manifestations of the same regional features. The location of geochemical provinces should be of greater importance in exploration than the location of metallogenic provinces, simply because a geochemical province can be identified early in an exploration program, while a metallogenic province cannot be defined until a number of ore discoveries has already been made. We have compared metallogenic provinces with geochemical provinces obtained by regional geochemical mapping in Fennoscandia (mainly data from the Nordkalott Project) and other places such as England, Wales, Germany and Alaska in order to study to what degree large-scale geochemical dispersion patterns can be associated with clusters of economically interesting mineral deposits.It is concluded that metallogenic provinces lie within or coincide with a number of geochemical provinces, some of which may have causal relationships with the ore deposits. It can be assumed that an enormous hierarchy of large and small geochemical provinces exist at the earth's surface. The main features of this system would be detectable by worldwide low-density geochemical mapping. Such mapping should be performed in order to shorten the time lapse between possible rises in the demand of certain raw materials and their supply. Worldwide geochemical mapping would also contribute to a better understanding of major geochemical processes of the Earth and provide baselines for environmental research.     

Holocene vegetation and climate history on a continental-oceanic transect in northern Fennoscandia based on pollen and plant macrofossils

Changes in tree-line, mean July temperature (T _jul ) and mean annual precipitation (P _ann ) for the last 10 200 cal. yr BP are reconstructed on the basis of pollen and plant macrofossils preserved in lake sediments from two sites near the present-day tree-line in Troms, northern Norway. Quantitative climate reconstructions are performed using pollen-climate transfer functions based on WA-PLS regression. Early Holocene Betula pubescens forests were gradually replaced by Pinus sylvestris at Dalmutladdo (355 m a.s.l.) starting about 7000 cal. yr BP. The local presence of pine woodland at that time is supported by finds of stomata and plant macrofossils and by high pollen accumulation rates. Until about 4000 cal. yr BP the P. sylvestris tree-line was 250-300 m higher than today, suggesting T _jul about 2.0°C higher than at present. The later part of the Holocene has a cooler and moister climate and an increasing development of mires and fern-rich vegetation, as shown by increases of Sphagnum and fern spores and the re-establishment of B. pubescens woodland. The reconstructed T _jul from the two sites shows similar trends to previously published data, with T _jul 1-2°C warmer between 9500 cal. yr BP and 2000 cal. yr BP T _jul . Maximum T _jul values occur between 8500 and 4500 cal. yr BP, after which there is a gradual decrease in T _jul .     

Hydrochemical method of prospecting in northern swamp areas

Presented here are the results of the study of surface (hypergenous) migration of a number of chemical elements in a swampy area of the northwestern Siberian Platform. The migration mode of a number of chemical elements, and their relationship with the ore bodies, were determined from a study of various natural objects (water, peat, iron gels, etc.). Geochemical exploration criteria for the bornite-chalcocite ores are cited. -- Author.     

Archean of Greenland and Fennoscandia

The North Atlantic craton in southern West Greenland mainly consists of a tectonic collage of Mesoarchean continental crustal terranes, which were amalgamated at c. 2.7 Ga and are currently exposed at mid-crustal amphibolite to granulite facies levels. Tonalitic orthogneisses predominate, intercalated with slightly older tholeiitic to andesitic metavolcanic rocks and associated gabbro-anorthosite intrusive complexes. The North Atlantic craton also contains enclaves of Eoarchean, c. 3.86-3.6 Ga orthogneisses and supracrustal rocks including the Isua greenstone （or supracrustal） belt. This is the oldest known assemblage of rocks deposited at the surface of the Earth, comprising mafic pillow lavas, banded iron formations and metasedimentary schists with local disseminated graphite of possible biogenic origin. Eoarchean rocks have not been found in Kola and Karelia in Fennoscandia where most rocks are 2.9-2.7 Ga tonalitic-trondhjemitic-granodioritic orthogneisses with intercalated coeval greenstone belts and amphibolites. Mesoarchean 3.0-3.2 Ga rocks are found in the eastern and western parts of the Karelian province. Subduction-related rocks like the Iringora supra-subduction type ophiolite and basalt-andesite-dacite-rhyolite series volcanic rocks in many greenstone belts, as well as eclogites are found in the Archean of Fennoscandia. A clear distinction between Greenland and Fennoscandia is the abundance of 2.75-2.65 Ga igneous rocks in Fennoscandia which indicates that these two cratons had a separate evolution during the Neoarchean.     

New radiocarbon dates from Finnish mammoths indicating large ice-free areas in Fennoscandia during the Middle Weichselian

New radiocarbon dates from Finnish subfossil mammoth material (Mammuthus sp.), transported by glacial ice, range in age from ca. 32000 to ca. 22500 yr BP. These results suggest that there was a larger ice-free area in Fennoscandia during the Middle Weichselian than previously assumed. In addition, two dates are also presented for bones found in clay with a different transport history. Copyright © 1999 John Wiley & Sons, Ltd.     

Occurrence of springs in massifs of crystalline rocks,northern Portugal

An inventory of artesian springs emerging from fractures (fracture springs) was conducted in the Pinh?o River Basin and Morais Massif, northern Portugal, comprising an area of approximately 650 km². Over 1,500 springs were identified and associated with geological domains and fracture sets. Using cross-tabulation analysis, spring distributions by fracture sets were compared among geological environments, and the deviations related to differences in rock structure and, presumably, to differences in deformational histories. The relation between spring frequencies and rock structures was further investigated by spectral determination, the model introduced in this study. Input data are the spring frequencies and fracture lengths in each geological domain, in addition to the angles between fracture strikes and present-day stress-field orientation (θ). The model's output includes the so-called intrinsic densities, a parameter indexing spring occurrence to factors such as fracture type and associated deformational regime and age. The highest densities (12.2 springs/km of lineament) were associated with young shear fractures produced by brittle deformation, and the lowest (0.1) with old tensional and ductile fractures. Spectral determination also relates each orientation class to a dominant structural parameter: where spring occurrence is controlled by θ, the class is parallel to the present-day stress-field orientation; where the control is attributed to the length of fractures, the spring occurrence follows the strike of large-scale normal faults crossing the region. Electronic Publication     

Early Weichselian interstadial (MIS 5c) summer temperatures were higher than today in northern Fennoscandia

Only fragmentary biostratigraphical interstadial data exist from northern European high latitudes. The palaeoenvironmental interpretations for the early part of the Last Glaciation in northern Fennoscandia are mainly based on palynological evidence that suggests open birch woodland and a sub-arctic climate. Plant macrofossils from the Sokli sediment sequence in Finnish Lapland provide different evidence of interstadial climate conditions. The assemblage includes several species that currently have considerably more southern distribution ranges. This indicates that ca 100,000 years ago summer temperatures were warmer than today. The mean minimum July temperature may have been as high as 16 °C and the effective temperature sum may have been 1000 in day-degree units (d.d.), the modern values being 13 °C and 650 d.d., respectively. The contemporary astronomical forcing mechanisms may have resulted in a weaker north–south temperature gradient and a longer growing period, creating more favourable climate conditions compared with today.     

Hydrogeochemistry of the groundwater flow system in a crystalline terrain: a study from the Kurunegala district,Sri Lanka

Water samples collected from dug wells and tube wells from the Kurunegala District of Sri Lanka have been studied for their major hydrogeochemical parameters to understand the chemical quality of water in the terrain. The region is composed of Precambrian metamorphic rocks where groundwater is only available in the regolith and along weak structural discontinuities. The study of the major chemical constituents of groundwater revealed several relationships with the aquifer lithology. Groundwater from mafic rocks have high dissolved solids, while quartzose metaclastic rocks yield water with low dissolved solids. The study area displays very low SO₄ ²⁻ contents of the groundwater. The chloride content is higher in the dry regions and in terrains underlain by pink granite and marble/calc gneiss while areas with marble, as expected, show high concentrations of Ca and Mg ions. The waters in the region can be classified into non-dominant cations to Na + K dominant and Cl⁻ and HCO₃ ⁻ dominant types. Water from charnockite-bearing areas tends to have non-dominant cations and more CO₃ ²⁻ + HCO₃ ⁻ types. Effects such as soluble salts in the regolith, fracture intensity and climatic variations play a significant role in the behavior of the hydrogeochemistry in the area.     

Paleoproterozoic evolution of Fennoscandia and Greenland

The Paleoproterozoic evolution of Fennoscandia and Greenland can be divided into major rifting and orogenic stages. The Paleoproterozoic rifting of Fennoscandia started with 2.505-2.1 Ga, multiphase, southwest-prograding, intraplate rifting. Both Fennoscandia and Greenland experienced 2.1- 2.04 Ga drifting and separation of their Archean cratons by newly-formed oceans. The main Paleoproterozoic orogenic evolution of Fennoscandia resulted in the Lapland-Kola orogen （1.94-1.86 Ga） and the composite Svecofennian orogen （1.92-1.79 Ga）. The Paleoproterozoic orogens in Greenland, from north to south, are the lnglefield mobile belt （1.95-1.92 Ga）, the Rinkian .fold belt/Nagssugtoqidian orogen （1.88-1.83 Ga） and the Ketilidian orogen （c. 1.8 Ga）. The Lapland-Kola orogen, Inglefield mobile belt and the Rinkian fold belt/Nagssugtoqidian orogen are continent-continent collision zones with limited formation of new Paleoproterozoic crust, whereas the Ketilidian orogen displays a convergent plate-tectonic system, without subsequent collision. The composite Svecofennian orogen is responsible for the main Paleoproterozoic crustal growth of Fennoscandia.     

Analysis of drought areas in northern Algeria using Markov chains

Journal of Earth System Science - The present work studies the trends in drought in northern Algeria. This region was marked by a severe, wide-ranging and persistent drought due to its...