摘要:

Geochronological investigations in south-eastern Sweden, based on U–Pb, Rb-Sr and K–Ar determinations, yield ages between 2465 Ma and 900 Ma. The oldest age, 2465 Ma, is obtained on zircons from the Västervik quartzite. Intrusion of synkinematic Svecokarelian granites occurred between 1970 Ma and 1840 Ma ago. Intrusion of late-kinematic Svecokarelian granites then followed, accompanied by wide-spread migmatization, deformation and folding affecting the older rocks. Between 1730 Ma and 1655 Ma, different generations of the Småland porphyries and Småland granites were emplaced. The last dated activity in postorogenic time was the intrusion of the Småland dyke porphyries 1655 Ma ago. The effect of the intrusion of the Småland granites was intense in the Västervik area and caused a resetting of the Rb-Sr ages of the older granites to 1665–1655 Ma. The lowering of the K–Ar ages to approximately 1400 Ma is probably due to anorogenic intrusions, like the Götemar granite at 1380 Ma, and metamorphic events in southern and south-western Sweden. The K–Ar results also confirm that the Sveconorwegian orogeny had no influence in south-eastern Sweden.

ISSN:0016-786X    

DOI:10.1080/11035897809454454

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Abnormal concentrations of magnesia are frequently associated with massive, Cu–Zn-bearing, sulfide (pyrite and/or pyrrhotite) deposits. Research on some reported occurrences of magnesia concentrations associated with volcanogenic, massive sulfide deposits suggests that such concentrations may result from syngenetic, metasomatic alteration of volcanic rocks in the vicinity of submarine volcanic centers by hydrothermal solutions and sea-water. Inasmush as the hydrothermal solutions consist of sea-water heated during convective circulation through the volcanic pile, the eventual source of magnesia is, in all cases, the sea-water. Cordierite–anthophyllite rocks are developed through thermal metamorphism of the altered volcanic rocks. It is suggested that this explanation is also appropriate to the cordierite–anthophyllite and other rocks of the “magnesia metasomatic” suites of Orijärvi in Finland and other similar deposits occurring in south-western Finland and central Sweden.

ISSN:0016-786X    

DOI:10.1080/11035897809454455

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Age measurements on Svecokarelian rocks of the Norvijaur area demonstrate (a)that the microcline granite, intersecting a metasupracrustal belt, has a whole-rock Rb-Sr age of 1915 ± 20 Ma with an intercept of 0.7025 ± 0.0007 and (b)that the gneissic granodiorite, lately interpreted as a basement to the above metasupracrustals, has a U–Pb zircon age of 2010 ± 40 Ma and a Rb-Sr whole-rock age of 1925 ± 120 Ma with an intercept of 0.7033 ± 0.0006.

ISSN:0016-786X    

DOI:10.1080/11035897809454456

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Sphalerite from the upper sandstone ore of the Laisvall sandstone lead–zinc deposit contains two-phase, primary, pseudosecondary and secondary inclusions. The inclusions homogenize at a modal value of 155°C and melt at −22°C. The secondary inclusions, which include necked-down types, tend to homogenize at +200°C and melt at −27°C. A fourth type of inclusion has been observed which contains a single dark phase, probably hydrocarbons. The melting temperatures of the primary inclusions indicate a strong Na-Cl brine with 24 equivalent wt.-% NaCl. The freezing temperatures of −60 to −90°C indicate that the trapped fluid contained calcium. These preliminary fluid-inclusion data suggest that the Laisvall sphalerite was precipitated at around 155°C from a concentrated Na-Ca-Cl brine.

ISSN:0016-786X    

DOI:10.1080/11035897809454457

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

The polygonal protocorallite in circumrotatory colonies and the auloporoid stage in hemis-pheroidal colonies of the tabulateFavosites forbesiMilne-Edwards & Haime may indicate the presence of asexual as well as sexual reproduction in favositids. The supposedly asexual phase is compared with gemmule formation in demosponges. Growth within colonies ofFavosites forbesiis lateral and not intermural.

ISSN:0016-786X    

DOI:10.1080/11035897809454458

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

In order to enhance the reliability and precision of the ecostratigraphy of the Quaternary of the Oslo Fjord area, an analysis of selected faunas has been made, for the purpose of determining their relationship to Thorson's Arctic-animal communities and their trophic structure, and especially of reconstructing the original biocoenosis from the observed taphocoenosis. The “noise” due to ice-rafted fossils has been estimated, and it is concluded that epifaunas may appear “warmer” than infaunas from the same environment, when interpreted by conventional methods. Discrepancies in the distribution of some species are attributed partly to the comparatively low latitude of the Oslo Fjord area, and partly to our incomplete knowledge of parts of the Recent faunas. The tentative, preliminary model indicates that the hydrological conditions changed from those of an open, ice-margin shelf-up to and during the Younger Dryas time-to those of an Arctic fjord, after the ice had retreated from the Ra line.

ISSN:0016-786X    

DOI:10.1080/11035897809454459

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

The data used for the construction of sea-level curves in north-western Europe are similar, but interpretations of these data differ. The results show the restoration of sea-level during the Holocene either as an exponential curve or as a curve with marked oscillations. The criteria used to establish the sea-level curve in west Lancashire, England, are described. A core from Downholland Moss, Lancashire, shows that the marine transgressions and regressions recorded there may be the result of a changing sea-level as one interpretation of the data. Index points on some other sea-level curves are briefly examined and tested against the criteria enunciated earlier.

ISSN:0016-786X    

DOI:10.1080/11035897809454460

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

The results of experiments performed to evaluate the EDTA method of pre-treating bones are given for newly dated samples older than one thousand years. Inter-laboratory checks using three samples, together with checks using samples measured exclusively in Uppsala, indicate that the EDTA method allows of the reliable pre-treatment of bones. Samples subjected to different HCl treatments may yield faulty results. In all probability, the HCl treatment can be improved to produce reliable results.

ISSN:0016-786X    

DOI:10.1080/11035897809454461

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

ISSN:0016-786X    

DOI:10.1080/11035897809454462

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Investigation of the mineralogy and paragenesis of the fluorite from the Kerio Valley shows that the mineralization resulted from residual magmatic solutions, which also led to the replacement of the crystalline limestone. Two types of inclusions–primary and secondary–are recognised. Four varieties of fluorite occur in the area. They are paragenetically related in the following order: white and yellow-brown varieties mineralized first, then the dark-grey variety and lastly the violet one.

ISSN:0016-786X    

DOI:10.1080/11035897809454463

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor