Jökull - 01.12.1987, Side 12

indicate a relatively primitive undegassed mantle source
and have been correlated with the presumed mantle
plume under the SE-part of central Iceland.
Anomalous concentrations of mercury in soil and of
radon in soil air in the Hrafntinnusker area reflect sub-
surface permeability anomalies controlling upflow of
geothermal steam. The anomalies form distinct linear
patterns striking NE-SW and NW-SE. The former direc-
tion is parallel with the present day tectonic fabric, but
the latter with an earlier tectonic fabric.
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