Magnetiska egenskaper hos Öje-Diabasen, Dalecarlia
Jotnian lavasDalarnaDalecarliaCentral-north SwedenöjeöjebasaltöjediabasePaleomagnetismMagnetic susceptibility
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.