The Genesis of Pegrnatites

• Main Author: Enzmann, Robert Duncan
• Format: Text
• Language: English
• Published: UNI ScholarWorks 1958
• Subjects: Fennoscandia
• Online Access: https://scholarworks.uni.edu/pias/vol65/iss1/44; https://scholarworks.uni.edu/cgi/viewcontent.cgi?article=2732&context=pias

Pegmatites are usually thought of as late magmatic emanations from cooling batholithic masses; however, in recent years doubt has been cast on the intrusive nature of many of the larger granitic masses. The granite-gneiss massif used as an example in this discussion is the Kheis granitized geosyncline of South West Africa and the Union of South Africa. From the top downward it is a pile of metavolcanics, gray gneiss and three cyclothemes of metasediments. This complex was previously called the Namaqualand granite-gneiss batholith and thought to be intrusive. If massif is neither intrusive nor batholithic in nature, associated pegmatites cannot originate from its late magmatic products. In addition to the example of the Kheis System, phenomena of the Svionian in Fennoscandia, Hercynian in Corsica and Beltian in Idaho will be mentioned.