摘要:

An introduction to the general problems and procedures of the paper is given, and the background and approach are indicated. Zoned granitic pegmatites are divided into four groups with respect to major constituents. Simple pegmatites, composed mainly of biotite, plagioclase, microcline, and quartz, are distinguished from more complex ones with muscovite, late albite, and lithium minerals respectively. Two types of internal zoning are recognized. They differ in the nature of outer zones, which are made up of granite and graphic granite in one pattern, and of quartz and quartz-muscovite assemblages in the other. The first type is preferentially developed in simple pegmatites, and the other one in more complex deposits. Outer zones of the second type pattern mineralogically resemble inner zones, especially the quartz core and its margin, and therefore this pattern is considered to be reversed, and the pattern of simple pegmatites is chosen as a basis for the later discussion. It is shown that pegmatites crystallized from the walls inward and that internal zoning developed rapidly, and not in response to secular changes in geologic conditions. Internal spatial zones are not accepted as strictly synchronous or paragenetic formations. The following main paragenetical groups are recognized instead: the granitoid, the graphic granite, and the pegmatoid zones, the core margin, alkali replacement, and core margin mica groups, and the quartz core and late alterations. A schematic two-dimensional synopsis of mineralization in pegmatites is given, showing the correlation of minerals with development of pegmatites and paragenetical groups within these. Some features of wall rock alteration and of primary pegmatitic cavities are presented.

ISSN:0016-786X    

DOI:10.1080/11035895909449134

出版商:Taylor & Francis Group    

年代:1959

数据来源: Taylor

摘要:

Rocks belonging to the Svionian cycle of the Swedish Archean have been mapped and investigated on the small island of Riddarskäret in NE Uppland, Central Sweden. The main rock type is a synorogenic gneiss-granite of granodioritic-quartzdioritic composition, called Uppsala granite. Numerous fragments of amphibolite occur in this granite over the whole area. Sheets of acid supracrustal rocks (leptite) and of banded amphibolites are enclosed in the granite along the planes of schistosity of the latter. The banded amphibolites probably represent basic tuffites and tuffs, possibly also lavas. In the granite a diffuse banding in the direction of strike, possibly derived from highly assimilated supracrustal rocks, is sometimes found. The above rocks are cut by dikes of aplite, granite porphyry and by amphibolite dikes of three different generations, in the directions N80°W, NNW and N70°W, respectively. The youngest rock is a red pegmatite.

ISSN:0016-786X    

DOI:10.1080/11035895909449135

出版商:Taylor & Francis Group    

年代:1959

数据来源: Taylor

ISSN:0016-786X    

DOI:10.1080/11035895909449136

出版商:Taylor & Francis Group    

年代:1959

数据来源: Taylor

ISSN:0016-786X    

DOI:10.1080/11035895909449137

出版商:Taylor & Francis Group    

年代:1959

数据来源: Taylor

ISSN:0016-786X    

DOI:10.1080/11035895909449138

出版商:Taylor & Francis Group    

年代:1959

数据来源: Taylor

ISSN:0016-786X    

DOI:10.1080/11035895909449139

出版商:Taylor & Francis Group    

年代:1959

数据来源: Taylor

ISSN:0016-786X    

DOI:10.1080/11035895909449140

出版商:Taylor & Francis Group    

年代:1959

数据来源: Taylor

ISSN:0016-786X    

DOI:10.1080/11035895909449141

出版商:Taylor & Francis Group    

年代:1959

数据来源: Taylor

ISSN:0016-786X    

DOI:10.1080/11035895909449142

出版商:Taylor & Francis Group    

年代:1959

数据来源: Taylor

摘要:

Henry V. Howe and Laura Laurencich: Introduction to the study of Cretaceous Ostracoda. Louisiana State University Press, 1958, 536 pp, numerous illustrations. Price $ 7.50. Published October 26th, 1958

ISSN:0016-786X    

DOI:10.1080/11035895909449143

出版商:Taylor & Francis Group    

年代:1959

数据来源: Taylor