Early deformation in the Svecokarelian greenstone belt of the Kiruna iron district, northern Sweden
作者:
FrederickW. Vollmer,
StephenF. Wright,
PeterJ. Hudleston,
期刊:
Geologiska Föreningen i Stockholm Förhandlingar
(Taylor Available online 1984)
卷期:
Volume 106,
issue 2
页码: 109-118
ISSN:0016-786X
年代: 1984
DOI:10.1080/11035898409454620
出版商: Taylor & Francis Group
关键词: Kiruna iron district;Svecokarelian;Proterozoic;greenstone belt;structure;tectonics;diapirism;boudinage;extension;northern Norrbotten;Lappland;N6745;N6757;E2035;E1957
数据来源: Taylor
摘要:
The Proterozoic iron ores of the Kiruna district, northern Sweden, occur as discontinous lenses of magnetite and hematite up to 4 kilometers in length within a sequence of felsic porphyries. The association of low-grade felsic volcanics and sedimentary rocks with basaltic pillow lavas and granitic rocks shows a strong similarity to typical Archean greenstone belts. Primary younging indicators, bedding/cleavage relationships, and minor fold symmetries through the district suggest that the area occupies the eastern limb of a major antiform, cored by granitic rocks to the west. A steep regional cleavage, inhomogeneously developed through the district, suggests one major episode of compressional deformation. The cleavage and associated flattened clasts indicate a compression direction plunging 10°WNW. Elongate clasts, boudins, and fibrous veins indicate a strong extension plunging 60°SSE, parallel to fold hinge lines. Boudinage of the major ore bodies to produce their present distribution is compatible with the estimated strain of a single deformation. Diapirism is suggested as a likely explanation of the observed strain patterns.
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