Palaeomagnetism of the Ragunda intrusion and dolerite dykes, central Sweden
作者:
JohnD. A. Piper,
期刊:
Geologiska Föreningen i Stockholm Förhandlingar
(Taylor Available online 1979)
卷期:
Volume 101,
issue 2
页码: 139-148
ISSN:0016-786X
年代: 1979
DOI:10.1080/11035897909452572
出版商: Taylor & Francis Group
关键词: Palaeomagnetism;thermomagnetism;polar wandering;pole positions;intrusions;dykes;dolerite;gabbro;anorthosite;titanomagnetite;Proterozoic;Fennoscandian Shield;Ragunda;Jämtland;Västernorrland;central Sweden;N6302 N6322 E1650 E1600
数据来源: Taylor
摘要:
The large Ragunda intrusion (1320 Ma) and dolerite dykes cutting the intrusion near its western margin have been extensively sampled for palaeomagnetic study. After comprehensive alternating field and thermal demagnetisation, the intrusion yields a mean directionD= 20°,I= 46° (α95= 7°); both polarities are present. Two stages of dyke intrusion are identified from their magnetisations: a small number of dykes have directions similar to the Ragunda intrusion and the remainder yield a meanD= 182°, 7=24° (α95= 14°); both polarities are present in each case and neither dyke suite correlates with the magnetisations of post-Jotnian (ca. 1200 Ma) dolerites from elsewhere in the Fennoscandian Shield. Magnetisations reside in different phases of titanomagnetite, pyrrhotite is a locally important remanence carrier, but maghemite, although sometimes present, has not been identified as a significant carrier. The palaeomagnetic poles help to clarify the form of the apparent polar wander path for the Fennoscandian Shield in Late Proterozoic times.
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