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1 Uppsatser om Paleomagnetism - Sida 1 av 1

Magnetiska egenskaper hos Öje-Diabasen, Dalecarlia

A study of paleomagnetic remanence and anisotropy of magnetic susceptibility (AMS) has been performed on the Öje-Diabase in Dalarna, Sweden, and on basic dikes associated with the alkaliquartzsyenite/granite Noran-pluton in central Sweden. Based on isolation of directions of characteristic magnetization in the basic rocks, a division into three different groups (A,B,C) has been made. Group Aconsists of dolerites of Jotnian origin, both dolerites from the Öje-Diabase and dikes associated with the Noran-pluton are included in this group, making them coeval. Group B is suspected to show a re-magnetization from the later part of the Svekonorwegian orogeny. Group C belongs to the Blekinge-Dalarna-Dolerites (BDD). Thermal demagnetization of dolerites revealed two different types of demagnetization behaviours, one where magnetite clearly was the source of the remanence, and an other with a linear decrease in magnetization intensity. The measurements of magnetic anisotropy reveals a magnetic fabric with an almost horizontal foliation and a lineation that indicates a fairly uniform NNW/ S-SE flow direction of the magma..