Greenstones related to rifting and ocean basin opening in the Jofjället area, central Swedish Caledonides
作者:
Johan Sandwall,
期刊:
Geologiska Föreningen i Stockholm Förhandlingar
(Taylor Available online 1982)
卷期:
Volume 103,
issue 4
页码: 421-428
ISSN:0016-786X
年代: 1982
DOI:10.1080/11035898209453720
出版商: Taylor & Francis Group
关键词: Ocean-floor basalt;within plate basalt;tholeiite;alkaline basalt;geochemistry;trace element diagram;tectonic environment of formation;rifting;ocean basin;alteration processes;Caledonides;Støren greenstone;N6547 N 6551 E1436 E1446
数据来源: Taylor
摘要:
Two greenstone formations in the Jofjället area, central Swedish Caledonides, have been analysed for major and trace elements in order to establish their petrology and tectonic environment of origin. The formations — the Ruffe Greenstone and the Brackfjället Greenstone — are situated in the uppermost part of the Seve-Köli Nappe Complex. The enrichment in volatiles, depletion in SiO2, redistribution of CaO and alkali contents are certainly caused by post-eruptive alteration processes. The Ruffe Greenstone is a tholeiite of a transition type between ocean-floor and within-plate basalt, while the Brackfjället Greenstone is an alkaline basalt showing a clear within-plate basalt affinity. The basalts are possibly formed during the later stages of rifting and ocean basin opening in a near-continental environment. The basalts can probably be correlated with the Støren greenstone in Norway.
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