Permian magnetostratigraphy and end of the Kiaman Reverse Polarity
Superchron from the southeast Karoo Basin, South Africa.
Abstract
Paleomagnetic results and a ~2353 m-thick
magnetostratigraphic section for undeformed middle to late Permian rocks
in the southeast of the Karoo Basin of South Africa are reported.
Pseudo-single domain or single domain titanomagnetite, as well as
pyrrhotite, were identified as possible remanence carriers of a dual
polarity magnetization interpreted as the record of the Permian
geomagnetic field during the Kiaman Reverse Polarity Superchron and
subsequent Illawarra mixed polarity interval. The timing of remanence
acquisition is further constrained by the effect of Jurassic-aged
dolerite intrusions, which either partially or wholly overprint the
Permian remanence in their immediate vicinity. A paleopole at 53.2°S;
46.9°E and dp/dm = 5.9°/6.3° is calculated from the bedding-corrected
primary remanence that was corrected for the effects of inclination
shallowing using a correction factor of f = 0.6. This is comparable to
known Permian paleopoles from the southwest section of the Karoo Basin
and overlaps with the 280-210 Ma segment of the Gondwana apparent polar
wander path. The end of the Kiaman Reverse Polarity Superchron can be
correlated between the extremes of the Karoo Basin and reveal a
diachronous boundary between the Ecca and the Beaufort groups that is
calibrated for the first time.