Paleomagnetic analysis of Paleocene sedimentary strata in Chuan-Dian Fragment on the southeastern margin of the Tibetan Plateau and its tectonic implications

A paleomagnetic experiment was carried out on Paleocene red beds of Dayao basin in Chuan-Dian Fragment for studying the common phenomenon of inclination shallowing in western China and Central Asia. Paleomagnetic researches demonstrate that inclination shallowing of Paleogene red beds does not obviously exist in the study area. Combined with previous paleomagnetic studies and Cenozoic peripheral fault structures, the authors hold that Chuan-Dian Fragment has rotated as a rigid block with a little southward escape since middle Miocene, though magnitudes of tectonic rotation are significantly different in Chuxiong area, where there has occurred local structural rotation superimposition.