PERMIAN PALEOMAGNETISM OF THE NORTHERN TIEN-SHAN AND ITS TECTONIC IMPLICATIONS

As a part of structural and paleomagnetic investigations of the late Paleozoic and younger tectonism in the Tien Shan, Permian sedimentary and volcanic rocks were sampled at four localities within the Northern Tien Shan west of the Issyk Kyl Lake. After complete thermal demagnetization, prefolding characteristic components were isolated for four localities, one of which also yielded a synfolding magnetization. when compared with the European reference data, the inclinations of these Permian rocks appear to be close to the reference ones. Mean declination for the northernmost locality also agrees with the European data, while the results for the southern parts of the area point to counterclockwise rotations. Comparison with data from an independent study (Thomas et al., 1992) shows that the rotations predate Alpine deformation but probably postdate the initial stage of the folding which affected the Permian rocks. Analysis of paleomagnetic data from different parts of Kazakhstan together with our results from the Northern Tien Shan has led to the conclusion that these blocks had already been welded with the European plate in Permian time.