Y. Gallet et al., MAGNETOSTRATIGRAPHY OF THE KAVUR TEPE SECTION (SOUTHWESTERN TURKEY) -A MAGNETIC POLARITY TIME-SCALE FOR THE NORIAN, Earth and planetary science letters, 117(3-4), 1993, pp. 443-456
We present the magnetostratigraphy of the late Triassic pelagic Kavur
Tepe section from the Taurides (southwestern Turkey). The section inve
stigated is about 30 m thick and consists of fine-grained whitish lime
stones. The biostratigraphy, based on the conodont zonation, gives an
age from the Lacian 2 zone (lower Norian) to the Sevatian 2 zone (uppe
r Norian). The paleomagnetic analyses indicate very favourable behavio
ur, with two magnetic components which can be isolated both by thermal
and AF demagnetization. The magnetization is carried by magnetite and
goethite, which are clearly evident in IRM experiments. The first com
ponent of normal magnetic polarity has roughly the direction of the pr
esent-day field. The high unblocking temperature component shows direc
tions of both polarities. In total, fifteen magnetic polarity interval
s are observed within the Kavur Tepe section. The characteristic calcu
lated Fisherian mean direction is particularly tightly grouped: D = 22
0.2-degrees and I = 32.1-degrees, with K = 40.9, alpha95 = 1.7-degrees
and N(samp) = 179 (after bedding correction). Polarity correlations w
ith two other sections in Turkey and in Austria (Northern Calcareous A
lps) show that the Kavur Tepe sediments were deposited in the southern
hemisphere. By combining the magnetostratigraphic results from the Bo
lucektasi Tepe [1] and the Kavur Tepe sections, an almost complete Nor
ian magnetic polarity sequence is established, showing 30 magnetic int
ervals that are well calibrated with the conodont and ammonoid zonatio
ns. A magnetic reversal frequency close to about 2.7 reversals/Myr is
derived for the Norian. This medium frequency is in agreement with the
hypothesis of a long time constant (150-200 Myr) in the changes of th
e magnetic reversal frequency since the Kiaman reversed superchron.