A CASE STUDY OF THE EOGENE PALEOMAGNETIC POLE SITES AND CHARACTERISTICS OF MAGNETIC STRATA IN EASTERN YUNNAN, CHINA
Liang Qizhong, (Yunnan Institute of Geological Sciences) Ding Shen, (Institute of Geomechanics, Chinese Academy of Geological Sciences), Yu Ruiyan and Niu Zelin (Yunnan Regional Geological Investigation Party)
In order to carry out the paleomagnetic study on some major post-late Mes ozoic landmasses in China, 105 specimens were collected from the Tertiary strata in the Lunan basin and the Kunming basin on the southwestern margin of the Yangtze massif, respectively, from which 145 test specimens were prepared. All of these test specimens were treated using the thermal demagnetization technique and measured using the same Digico spinner magnetometer. As shown by the result of the study, the paleomagnetic pole site for the Eogenestrata of the Lunan basin is located at longitude 343.1°E and latitude 84.4°N and that for the corresponding strata of the Kunming basin at longitude 309.1°E and latitude 83.8°N, which are close to those for the corresponding strata in other regions in the world. The characteristics of the paleomagnetic polarity of the corresponding strata of the two basins are in the main consistent, and their polarity time scales are in accord with Heirtzler's magnetic polarity time scale for the late Eocene. The paleolatitudes are 21.9°N for the Lunan basin and 19.1°N for the Kunming basin respectively during the Eogene, which are quite close to those derived from the paleogeographic and paleoclimatic condations of the two basins.