摘要:

Age determinations utilizing the U/Pb method have been carried out on radioactive minerals in the Precambrian bedrock of Sweden. As a result, minerals from northern Sweden have been found to have an age of 1775–1845 m.y. but a more precise result could not be obtained. The pegmatites in the Östersund—Sundsvall area and the pegmatites and aplites in southeastern Sweden are 1380 and 1745 m.y. old respectively. A pegmatite associated with the Karlshamn granite and a granite on Romeleåsen each have ages of 1455 m.y. Some previously determined K/Ar ages are discussed and it is concluded that the uplift of the gneiss block in southwestern Sweden occurred during or after a period of igneous activity in western Sweden 935–1000 m.y. ago. The age data also indicate a contemporaneity between the deposition of the Dal formation in western Sweden and the Jotnian sandstones, the former being of marine lithology, the latter representing a terrestrial facies.

ISSN:0016-786X    

DOI:10.1080/11035896609448330

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

Rb/Sr whole rock age dating of sub-Jotnian volcanics in the Los region give an age of 1685 m.y., and of red Växjö-granitc in the Strålsnäs area an age of 1740 m.y. The results are in good agreement with U/Pb age data and disregard the existence of a Gothian cycle.

ISSN:0016-786X    

DOI:10.1080/11035896609448331

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

On the basis of the available age data from the Baltic shield it is pointed out that the classification of the Precambrian rocks in Sweden must be founded on a time scale of world wide acceptance. This time scale evidently can be based on periods of igneous activity contemporaneous on all continents. Such events seems to be the Grenville-Sveconorwegian period, the Penokean-Svecofennian period and the Algoman-Saamian period, all recorded in the northern hemisphere. The close of each of these periods may be chosen to represent the beginning of a new era. The resulting four Precambrian eras, tentatively named according to international agreement, represent the largest divisions of a time scale within which orogenies and local formations maybe placed by geochronological methods. Thus it is possible to discern in Sweden on one hand Svionian, Jotnian, and Dal formations and on the other Svecofennian and Sveconorwegian periods of igneous activity, and to coordinate these with a time scale established in the above manner.

ISSN:0016-786X    

DOI:10.1080/11035896609448332

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

This paper summarizes studies on the genesis of uranium ores in the Precambrian bedrock of Central and southeastern Sweden. The occurrence of uranium in the mineralizations described was detected during the boom period 1950–1960. None of these occurrences is of economic value. Several different paragenetic types occur, the most common probably being the pitchblende-bearing vein fillings and disseminations of uraninite in iron ores of Central Sweden. The well known Co-Ni-Bi-U paragenesis also occurs, as well as iron deposits possibly being mechanical accumulations and containing uraninite and monazite supposedly of detrital origin. Alteration of uranium minerals is light although a thin coating of secondary uranium minerals may occasionally be observed. More frequent is the formation of thucholite and radiogalena. To correlate the uranium mineralizations with major Precambrian events, minerals and rocks with stratigraphic key positions have been dated by the U/Pb and Rb/Sr whole rock method. As a result the age relationships in the Precambrian bedrock of Central and southeastern Sweden are also discussed.

ISSN:0016-786X    

DOI:10.1080/11035896609448333

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

Ampirulum, a new genus of beyrichiacean ostracodes (Craspedobolbinidae: Amphitoxotidinae) with very specialized sexual dimorphism, is described from the Silurian (s.l.) of the Baltic area. Only known species in the genus isBeyrichia reuteriKrause 1891 (syn.B. alataKummerow 1944,B. obliquaKummerow 1924).

ISSN:0016-786X    

DOI:10.1080/11035896609448334

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

The use of the symmetry concept permits the description of geological structures of all kinds from statistic points of view. The combination of the symmetry concept with the Schmidt net or with any equivalent diagrams allows representing these structures in a complete description. After an explanation of the systems of the symmetry concept, examples taken from the field of sedimentology and results of investigations of joints are given in order to introduce the consideration how to use the modified Schönfiies symbols for describing structures and multicyclic relief tectonics as well as to incorporate non-integrated structures into the known ones. Similar problems in the field of applied geology may be treated in the same way as purely scientific problems.

ISSN:0016-786X    

DOI:10.1080/11035896609448335

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

The author has investigated some glaciomorphological elements in a valley in western Jämtland, Sweden (see map). These elements consist of terraces and plains, which are now explained as accumulations in lateral meltwater between the mountain slope and an ice-tongue in the center of the valley. Earlier concepts of open ice-dammed lakes are not applicable to this case. A description of the materials in these terraces and plains are given, as well as their formation and construction. Finally, a theory is given on the ice recession in the investigated area.

ISSN:0016-786X    

DOI:10.1080/11035896609448336

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

Two recent geotechnical papers are reviewed in the light of considerations of the mineralogy of the Quaternary clays of Sweden.

ISSN:0016-786X    

DOI:10.1080/11035896609448337

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

ISSN:0016-786X    

DOI:10.1080/11035896609448338

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

L. J. Lawrence [Ed.]: Exploration and mining geology, with particular reference to the Commonwealth of Australia. VIIth Commonwealth Mining and Metallurgical Congress (Australia and New Zealand) 1965, Publication No. 2. 365 pp. Melbourne 1965. Reviewed by Olof H. Ödman.

ISSN:0016-786X    

DOI:10.1080/11035896609448339

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor