THE LATE PERMIAN POLE OF THE WESTERN JIUQUAN BASIN (NW CHINA) AND ITS TECTONIC IMPLICATION
Meng Zifang Huang Huafang Chen Yanzhang (Lanzhou Institute of Geology, Academia Sinica) Robert S.Coe (Earth Sciences Board of the University of California at Santa Cruz)
A mean direction of-28 °N/132.9° E (α-95 = 4.7, k = 47.1) and a corresponding pole at 42.4 ° N / 350.9 ° E (α-95 = 3.9, K = 67.8) were obtained from 21 out of 33 Upper Permian samples of continental sedimentary rocks collected from the Western Jiuquan Basin, over 1300km west to the places where previous paleomagnetic researches were con- ducted for North China Block. The fair consistency of our results with the preexisting coeval ones demonstrates paleomagnetically that this area was a part of North China Block during Late Permian. If all the preexisting data from both North China and Tarim Blocks are assumed to be precise enough, then the ancient boundary between them should have been west to the Western Jiuquan Basin. The predecessor of Altyn fault or an analoque seems to be the first possible candidate to be chosen as this kind of ancient boundary.