NEW PALEOMAGNETIC DATA FROM CENTRAL IRAN AND A TRIASSIC PALAEORECONSTRUCTION

Citation
Hc. Soffel et al., NEW PALEOMAGNETIC DATA FROM CENTRAL IRAN AND A TRIASSIC PALAEORECONSTRUCTION, Geologische Rundschau, 85(2), 1996, pp. 293-302
Citations number
29
Categorie Soggetti
Geosciences, Interdisciplinary
Journal title
ISSN journal
00167835
Volume
85
Issue
2
Year of publication
1996
Pages
293 - 302
Database
ISI
SICI code
0016-7835(1996)85:2<293:NPDFCI>2.0.ZU;2-X
Abstract
New pole positions for Triassic and Cretaceous times have been obtaine d from volcanic and sedimentary sequences in Central Iran. These new r esults confirm the general trend of the Apparent Polar Wander Path (AP WP) of the Central-East-Iran microplate (CEIM) from the Triassic throu gh the Tertiary as published by Soffel and Forster (1983, 1984). Two n ew palaeopoles for the Triassic of the CEIM have been obtained; limest ones and tuffs from the Nakhlak region yield a mean direction of 094.0 degrees/25.0 degrees, N=12, k=4.1, alpha(95) = 24.7 degrees, after be dding correction, corresponding to a palaeopole position of 310.8 degr ees E; 3.9 degrees S, and volcanic rocks from the Sirjan regions yield a mean direction of 114.5 degrees/35.1 degrees, N=44, k=45.9, alpha(9 5)=3.2 degrees after bedding correction and a palaeopole position of 2 95.8 degrees E; 10.3 degrees N. Combining these with the two previousl y published results yields a new palaeopole position of 317.5 degrees E; 12.7 degrees N, for the Triassic of the CEIM, thus confirming that large counterclockwise rotations of the CEIM have occurred since the T riassic time. New results have also been obtained from Cretaceous lime stones from the Saghand region of the CEIM. The mean direction of 340. 7 degrees/26.3 degrees, N=33, k=44.3, alpha(95)=3.8 degrees, and the c orresponding palaeopole position of 283.1 degrees E; 64.4 degrees N, i s in agreement with previously determined Cretaceous palaeopole positi ons of the CEIM. Furthermore, results have also been obtained from Tri assic dolomite, limestone, sandstone and siltstone from the Natanz reg ion, which is located to the west of the CEIM. A total of 161 specimen s from 44 cores taken at five sites gave a mean direction of the five sites at 033.3 degrees/25.1 degrees, N=5, k=69.0, alpha(95)=9.3 degree s and a palaeopole position of 167.2 degrees E; 53.7 degrees N. They p ass the positive fold test of McElhinny (1964) on the level of 99% con fidence. This pole position is in fairly good agreement with the mean Triassic pole position of the Turan Plate (149 degrees E; 49 degrees N ). It indicates that the area of Natanz has not undergone the large co unterclockwise rotation relative to the Turan plate since the Triassic , which has been shown for the CEIM. A Triassic palaeogeographic recon struction of Iran, Arabia (Gondwana) and the Turan Plate (Eurasia) is also presented.