摘要:

The distribution of the main elements in two often more or less serpentinized, olivinitic—peridotitic bodies in the Björkvattnet—Virisen—Fättjarn area of the Swedish Caledonides of Västerbotten County was found to vary in the outcrops according to a compositional layering. This can be illustrated by calculating the normative mineral components of the rock, i.e. olivine and pyroxene. Olivinite/harzburgite interlayering and chromium-rich spinel banding have allowed of field identification of the compositional layering. It is obvious that all the analyses from the two investigated bodies can be plotted within the field of Alpine-type, ultramafic rocks. The ultramafic material is thought to be derived from a non-hydrous, refractory depleted upper mantle. At an early, probably pre-orogenic stage, a change from a peridotitic—dunitic state into a serpentinitic mineralogy occurred. Olivines and pyroxenes were converted into serpentine minerals. The serpentinites protruded, during Ordovician subduction, into a sedimentary, water-rich environment (Köli) and in some cases reached the surface. The serpentinites also protruded into the Seve and, during later metamorphism, came into an environment with a rather high temperature, resulting in dehydration and crystallization of olivine-rich rocks.

ISSN:0016-786X    

DOI:10.1080/11035897809454470

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

A lithotectonic sequence has been studied in the Nordhallen—Duved—Greningen area and found to consist of a Precambrian basement overlain by four distinct thrust-nappe units—the Kallsjon, Quartzite—Mylonite, Seve and Köli Nappes. This nappe sequence is folded by the Mullfjället Antiform, the western limb of which composes much of the investigated area. An important tectonic feature, recognized during the investigation, is the lenticular geometry of these nappe units, as well as individual formations within the highest tectonic unit—the Köli Nappe. The stratigraphy within the Köli Nappe of the Tännforsen area is described in detail and correlated with the classic Köli stratigraphy in Västerbotten. Study of the minor structures within the Köli Nappe reveals a polydeformational sequence (F1, F2, F3). Isoclinal to tight folding occurred prior to (F1) and during (F2) the development of the main foliation (S2). The third-phase structures (F3) deformed the main foliation and are open, asymmetric kink folds and box folds. The peak of the metamorphism of the Köli rocks, represented by garnet and biotite porphyroblastesis, was established prior to the formation of S2.

ISSN:0016-786X    

DOI:10.1080/11035897809454471

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

ISSN:0016-786X    

DOI:10.1080/11035897809454472

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

At 66° N in the Scandinavian Caledonides, there are three superposed, extremely allochthonous, high-grade-metamorphic, and competent nappes. The present tectonic analysis shows that the middle one, the Krutfjellet Nappe, which is separated from the other two by low-grade-metamorphic and incompetent units, consists of several gigantic, laterally semiconnected, quasi-lenticular parts. These major structures are discussed in their polyphase context, and a pinch-and-swell mechanism is proposed for the generation of the discontinuous nappe; the order of imbrication is also considered. The named and defined allochthonous units, lenses, and folds are the Jofjället Nappe, the Krutfjellet Nappe, the Atofjället Nappe, the Joesjö Nappe, the Tärna Nappe, the Lappland Nappe, the Krutfjellet Lens, the Norra Storfjället Lens, the Södra Storfjället Lens, the Atofjället Synform, and the Jofjället Synform.

ISSN:0016-786X    

DOI:10.1080/11035897809454473

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

The Swedish Mineralogical Society was founded in 1928 and celebrated its jubilee in March 1978. The article describes the major features of its history, the temporal trends in the subject matter of papers presented at the meetings and their relation to the general development of the field.

ISSN:0016-786X    

DOI:10.1080/11035897809454474

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

ISSN:0016-786X    

DOI:10.1080/11035897809454475

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

The study of calcareous crusts, under the scanning electron microscope (SEM), as features of pedological development on both wet and dry Arctic sites shows that these crusts have a sequence of forms, with varied and complex grain microforms and layered internal structure. The presence of Mg is very variable and is not significantly related to the assumed development sequence. The various carbonate crusts bear witness to the development of pedological features and processes related to the intensive dissolution of carbonates by melt-water, melting ground-ice and summer rainfall, all acidulated by contact with organic matter in the soil. The reprecipitation on the undersides of stones is achieved by intense evaporation of this soil solution and a sequence of precipitated forms is described which is independent of the presence of algae, permafrost-table depth and geomorphic site or age. Grain-size and calcitan thickness are variable at all stages of development.

ISSN:0016-786X    

DOI:10.1080/11035897809454476

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

ISSN:0016-786X    

DOI:10.1080/11035897809454477

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

The geochemistry of a small stream has been studied by repeated sampling of sediment and peat at two sites typical for northern Sweden. A geochemical model for the processes responsible for the element distributions in a small stream is proposed. According to the model the metallic element concentrations are formed by reaction between the stream water and fresh discharging ground water. The reaction normally takes place in the sediment bed and is governed by the differences in physical and chemical properties of the two water bodies. The model makes it possible to explain qualitatively the rapid changes in element concentrations along the stream, the time dependence of the stream sediment concentrations, the transport mechanism from the source in the bedrock to the stream channel, the symmetrical distributions of element concentrations at one site and also the relationships between concentrations in sediment and peat samples. The detailed properties of the element distributions are discussed both with regard to the model and for exploration. For exploration purposes it is important to discriminate between the influences of local environmental conditions and those of the bedrock composition.

ISSN:0016-786X    

DOI:10.1080/11035897809454478

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

The north-west European shelf and coasts, which include rising, subsiding and semi-stable areas, can be regarded as an immense “sea-level laboratory” where the details can be studied and checked. In response to the Late Weichselian Glaciation, Fennoscandia has gone up by 830 m in the centre and the North Sea basin has subsided by 170 m. This indicates rapid movements of a low-viscosity asthenosphere. Sea level oscillations are recorded both in areas of uplift and of subsidence. The close age correlation between these oscillations indicates a eustatic background. The amplitude can be checked against the South Scandinavian shoreline diagram system. The fluctuations are all of low amplitude, with no regression during the last 8000 years exceeding 1 m. The South Scandinavian records are now extended to the present and integrated with palaeomagnetic and palaeotemperature analyses. The eustatic curve calculated fits very well with data available for north-western Europe. There are few examples of non-eustatic local meteorological, hydrological and oceanographical effects. The eustatic curve established is believed to give a reliable eustatic record for the entire north-west European (north-east Atlantic) region. By comparison with other eustatic curves the palaeogeoidal or geoidal-eustatic changes can be recorded.

ISSN:0016-786X    

DOI:10.1080/11035897809454479

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor