ISSN:0016-786X    

DOI:10.1080/11035898409454607

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The Svecokarelian supracrustal and infracrustal rocks of the Umeå district have been studied within an area of about 350 km2. Intrusive rocks constitute ca. 5% of the research area, a considerably lower proportion than in other parts of the Våsterbotten county. The intrusives of Umeå are now mostly gneissose and conforming to the surrounding metasediments. High metamorphism and locally moderate veining and/or migmatization are normal features of the intrusive rocks. The range of mineralogical and chemical composition is from gabbro to tonalite and a low Al-value points to I-type granitoids. These rocks may be more comparable with the primorogenic-synorogenic intrusives of the Jörn suite than, as suggested earlier, with those of the Revsund granite.

ISSN:0016-786X    

DOI:10.1080/11035898409454608

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Proterozoic molybdenite occurrences in Sweden are spatially associated with acid volcanics. To test if mineralization is caused by remobilization of molybdenum in such rocks, fifty samples from northern Sweden have been analysed for major elements and 15 trace elements. Volcanics from the mineralized Rappen district and Vidsel area, situated on the Proterozoic continental domain north of the Skellefte district, have lower Mo-contents than the calc-alkaline submarine Skellefte volcanics. It is therefore concluded that acid volcanics are not the source for molybdenum mineralization. The association between molybdenite occurrences and acid volcanics in northern Sweden is tectonic, suggesting that the late orogenic development of the Rappen district and the Vidsel area, characterized by block movements and development of rift systems, is favourable for generation and emplacement of the granites responsible for molybdenite mineralization.

ISSN:0016-786X    

DOI:10.1080/11035898409454609

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Ferro- and ferristilpnomelane occur in the dolerites and associated rocks of the Hällefors dyke in Södermanland, south central Sweden. The secondary mineral assemblage is: stilpnomelane, ferroactinolitic amphibolc, iron-rich chlorite, epidote, albite, titanite and quartz. This greenschist facies assemblage has probably formed during an episode of non-deformational alteration. The ferristilpnomelane was most likely formed by oxidation of ferrostilp-nomelane under atmospheric conditions.

ISSN:0016-786X    

DOI:10.1080/11035898409454610

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

ISSN:0016-786X    

DOI:10.1080/11035898409454611

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Six radiocarbon datings have been carried out on water mosses from a Late Weichselian sequence in Lake Sännen, Blekinge, SE Sweden. Three of the dates seem, from pollen-stratigraphical point of view, to correspond to the Older Dryas Chronozone and the very beginning of the Allerød Chronozone. As no contamination of the dated material can be demonstrated the dates are considered reliable. An age of 12 100–12 250 years B.P. is indicated for the Older Dryas, which is older than thought before. Added to the local varve chronology these dates suggest that SE Sweden was deglaciated 12500–12600 yr B.P. The climatic amelioration at the beginning of the Allerød interstadial is placed at about 12 100 yr B.P., but whether it was preceded by a distinct cold phase or not, is still doubtful. Because of that and its short duration the Older Dryas is proposed omitted as a chronozone.

ISSN:0016-786X    

DOI:10.1080/11035898409454612

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

ISSN:0016-786X    

DOI:10.1080/11035898409454613

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

From two samples of the Upper Dalby Limestone of Dalarna and Västergötland the ostracode faunas gained by Wetzel's (hydrofluoric acid) method are mentioned and 4 new species of the generaHenningsmoenia, Vittella, Hemeaschmidtella and Jaanussoniaare described. The ostracode fauna confirms the age determination of corresponding erratic boulders (Backsteinkalk, 1B2-type) of Northern Germany.

ISSN:0016-786X    

DOI:10.1080/11035898409454614

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

ISSN:0016-786X    

DOI:10.1080/11035898409454615

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

In the years 1963–1979, altogether 176 Swedish earthquakes have been detected and located, mainly from records from the Swedish Seismograph Station Network (SSSN). The earthquakes have occurred within a belt from the southwestern to the northeastern part of the country and in northern Lapland. Corresponding local magnitudes are not greater than 4. b-values of the magnitude-frequency relation are 0.7 and 1.5 for magnitude intervals 2.2–3.0 and 3.0–3.9, respectively. The strain energy release has been rather regular during most of the time. The apparent increase of small-size shocks in recent years is due to improved instrumental facilities and not to a real increase of seismicity. The presented data can be used as a base for seismotectonic and seismodynamic studies of the Swedish bedrock.

ISSN:0016-786X    

DOI:10.1080/11035898409454616

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor