柴达木地块新生代古地磁新数据及其构造意义

New Cenozoic Paleomagnetic Data from Qaidam Massif and Their Tectonic Implications

5个新的古地磁数据结合已发表的成果反映了柴达木地块晚第三纪以来的旋转运动特征。东西部旋转运动的差异性反映了不同地区应力场方向变化特征 ,即从西到东从北转向北东 ,与震源机制解有很好的对应性。与塔里木南缘相对照 ,则更进一步说明了青藏高原北缘旋转变形的差异性。柴达木盆地和酒泉、肃北旋转方向的差异预示了两地区间存在左旋错动。

Five new paleomagnetic data together with previously published information on Cenozoic strata of Qaidam basin reveal the rotational feature of Qaidam block since Neogene. The rotational difference between the eastern part and the western part reflects the variation feature of the stress field direction in different areas, i.e., from east to west, the stress direction changes from north to northeast. This is in good accord with present day stress distribution deduced from focal mechanism of earthquakes. A comparison with the rotational feature of the southern rim of the Tarim basin further illustrates the difference of rotational deformation in different areas along the northern rim of the Qinghai Tibetan plateau. The opposite rotation direction implies the existence of left lateral dislocation between Qaidam basin and Jiuquan and Subei areas.