Jökull - 01.12.1990, Side 21

Figure 8. An attempted correlation of the inferred late Pliocene tillites with the geomagnetic polarity time scale.
Results of the paleomagnetic measurements from the diamictites are added to the paleomagnetic results from
the lava flows as published by McDougall et al. (1977) from Borgarfjörður, and Kristjánsson et al. (1980) from
Hvalfjörður. Numbers in parentheses refer to glacial horizons of McDougall et al. (1977) in Borgarfjörður
and Kristjánsson et al. (1980) in Hvalfjörður. — Tilraun til að tengja jökulset frá síðari hluta Plíósen
segultímaskalanum. Niðurstöðum segulmœlinga á setlagaeiningum er bætt inn í niðurstöður segulmælinga á
hraunlögum sem birst hafa í McDougali o.fl. (1977) frá Borgarfirði og Kristjánsson o.fl. (1980) frá Hvalfirði.
able, then this unit may be correlated with glacial de-
Posit 4 (diamictite unit 9) in the Hvalfjörður area (the
Botnsdalur section). This age was suggested for the
Hvalfjörður deposit based on magnetic polarity mea-
surements made in the field (Arason et alI 1974). A
short normal ”event“ was recorded from the lava di-
rectly undemeath the deposit which was interpreted as
the normal polarity Reunion-event of the Matuyama
ePoch. K/Ar ages for normally magnetized lavas from
different localities give ages for the Reunion event be-
tween 2.00 and 2.14 m.y. (Mankinen and Dalrymple,
1979; Clement and Kent, 1987).
It is emphasized here, that these correlations are
based on certain assumptions and that correlations of
the two sections with a paleomagnetic time scale are
problematic, mainly because the number of polarity
reversals within the time-span is not well known, be-
side the lack of absolute age determinations. The
lithofacies analysis and the inferred position of the
sediments relative to the magnetic polarity stratigra-
JÖKULL, No. 40, 1990 19