摘要:

Inz north central Sweden, the ca. 1250-Ma old Central Scandinavian Dolerite Group mainly comprises large flat-lying sheets essentially of alkali-basaltic olivine dolerite. The content of incompatible elements is somewhat lower than is average in alkali basalts. Geochemically, the dolerites are rather homogeneous and follow a liquid-descent line which is modified somewhat by the cumulation of early olivine. Mineralogical control of crystallization is particularly obvious in the Ni/Cr and K/Rb distributions. The contents and proportions of minor chemical constituents are discussed in relation to systems proposed for tectonic classification. The intrusion of the Central Scandinavian Dolerite Group was an intra-plate event coinciding in time with the early stages of the Sveconorwegian orogeny in western Scandinavia.

ISSN:0016-786X    

DOI:10.1080/11035897909448572

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Crustal velocity-depth models are presented from a deep seismic sounding profile across the Scandinavian peninsula. The Pg phases are influenced by local basement geology. Pg velocities as high as 6.4 km/s have been recorded over nappe units in the Caledonides. Along the Fennoscandian Shield part of the profile the velocity increases from about 5.4 to 6.0 km/s in an uppermost zone of the earth's crust, which is about 2 km thick. Faults have been detected in the uppermost part of the crust, one of which coincides with a shear zone deduced from purely geological reasoning. Velocity reversals in the Caledonides are invoked to explain the recorded data from the uppermost part of the crust. No velocity reversals have been detected along the Fennoscandian Shield part of the profile. A velocity increase from 6.3 to 6.7 km/s in a transition zone of some kilometres thickness divides the crust into an upper and lower part. The depth of the transition zone increases from 13 to 27 km below the eastern and western part of the profile respectively. Apparent Pnvelocities as high as 8.34 km/s have been recorded over a distance range of about 100 km. The energy recorded from the lower part of the lithosphere, from below the Mohorovičić discontinuity, is inconsistent with a homogeneous upper mantle. The average crustal thickness in the determined models is about 45 km and the average velocity below the eastern part of the profile is 6.6 km/s.

ISSN:0016-786X    

DOI:10.1080/11035897909448573

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Fifteen acanthomorphic acritarch species belonging to the genera Baltisphaeridium, Goniosphaeridium and Peteinosphaeridium from the Middle Ordovician Uhakuan Stage of the island of Odinsholm (Osmussaare) in Estonia are described by means of stereo-scanning technique. Seven species have been found to be stratigraphically confined to the Viruan Series (Middle Ordovician). The acritarch assemblages are biostratigraphically compared with assemblages from other Baltoscandian regions, for example, Gotland, Öland and Östergötland.

ISSN:0016-786X    

DOI:10.1080/11035897909448574

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Twenty-three exposures with ripple marks are listed, 14 of which are in the Slite Beds. Oscillation has formed at least some of the ripple marks. The wavelength ranges from a few centimetres to one metre. One major and two minor ripple-crest directions are observed, viz. NE-SW, E-W and N-S respectively. It is concluded that the wave marks in the Halla Beds and the Högklint Beds on Fåarö are parallel to the contemporaneous coastline.

ISSN:0016-786X    

DOI:10.1080/11035897909448575

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

The classical equation for concentration distribution of suspended sediment in open channel flow is valid for both field and laboratory data, provided that the bed material is of uniform size. For heterogeneous bed material, prevailing integration methods do not take into account bed material sorting. In order to evaluate the role of this sorting in influencing relative concentration and mean size profiles of suspended sediment, an integration procedure is outlined which assumes that the sediment sizes (in ϕ units) are normally distributed. Numerical evaluation of the integration equation for selected input values of the relevant variables shows the importance of the sorting factor. The efficacy of this factor depends on the flow strength and mean size of the bed material. In general, the effect of sorting is most pronounced in the case of low flow strength and coarse bed material.

ISSN:0016-786X    

DOI:10.1080/11035897909448576

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Chemical and cell-dimensional data for a barium feldspar from a previously reported occurrence are presented. The barium feldspar was found in a minor magnetite ore and a literature review of similar and of other occurrences in Sweden is also given. Despite the restricted size of the sample, the data reveal that the BaO content of the feldspar varies between 20 and 40 wt.%. In addition, indications were found of a small baryte content. However, no feldspars were found with a BaO content between 24 and 32 wt.%. Thus, the discontinuity in the K-Ba felspar series as discussed by other authors is apparently present also within this restricted sample. Obviously, several analyses and methods might be necessary for a dependable characterization of even such a small sample.

ISSN:0016-786X    

DOI:10.1080/11035897909448577

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

A specimen of Phaulactis sp. from an unknown locality of the Silurian of Gotland shows repeated damages to its epitheca. The breaks have healed in different ways by regeneration of the epitheca or by rejuvenation of the corallite. After the last injury the epitheca grew inwards, forming a roof-like cover over part of the dissepimentarium. During the last phase of life the form of the cake also changed. Possibly, the injuries were caused by fish.

ISSN:0016-786X    

DOI:10.1080/11035897909448578

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Tremadocian to basal Llanvirnian carbonate mudstones of southern Sweden contain hollow, orthogonal pentact or hexact calcareous spicules filled with calcite cement. Available data do not permit distinction from Calcihexactina franconica Sdzuy, 1969, from the Middle Cambrian of Germany.

ISSN:0016-786X    

DOI:10.1080/11035897909448579

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

ISSN:0016-786X    

DOI:10.1080/11035897909448580

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Pilger, A. & Rösler, A. (eds.), 1974: Afar between continental and oceanic rifting. (Proceedings of an international symposium on the Afar region and related rift problems, held in Bad Bergzabern, F. R. of Germany, vol. 2.)Interunion commission on geodynamics scientific report 16. Price ca. US$43.00, Sw. Kr. ca. 325.00. Reviewed by Ove Stephansson.

ISSN:0016-786X    

DOI:10.1080/11035897909448581

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor