MAGNETOSTRATIGRAPHY OF THE KAVUR TEPE SECTION (SOUTHWESTERN TURKEY) -A MAGNETIC POLARITY TIME-SCALE FOR THE NORIAN

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.